US20090305171A1

US20090305171A1 - Apparatus for scanning sites on a wafer along a short dimension of the sites

Info

Publication number: US20090305171A1
Application number: US12/481,447
Authority: US
Inventors: Eric Peter Goodwin; David M. Williamson; Michael B. Binnard
Original assignee: Nikon Corp
Current assignee: Nikon Corp
Priority date: 2008-06-10
Filing date: 2009-06-09
Publication date: 2009-12-10
Also published as: US8305559B2; US20090303454A1; US20090316131A1

Abstract

An exposure apparatus (210) for transferring a mask pattern (346) from a mask (212) to a substrate (214) includes a first site (315) having a first site dimension (348) along a first axis and a second site dimension (350) along a second axis that is perpendicular to the first axis. The second site dimension (350) is larger than the first site dimension (348). The exposure apparatus (210) includes an illumination system (218), a mask stage assembly (222), a substrate stage assembly (224), and a control system (228). The illumination system (218) generates an illumination beam (235) that is directed at the mask (212). The mask stage assembly (222) retains and positions the mask (212) along the first axis relative to the illumination beam (235). The substrate stage assembly (224) retains and positions the substrate (214) along the first axis. The control system (228) controls the illumination system (218), the mask stage assembly (222), and the substrate stage assembly (224) so that a portion of the mask pattern (346) is transferred to a portion of the first site (315) while the mask stage assembly (222) is moving the mask (212) along the first axis, and the substrate stage assembly (224) is moving the substrate (214) along the first axis.

Description

RELATED APPLICATIONS

This application claims priority on U.S. Provisional Application Ser. No. 61/060,411, filed Jun. 10, 2008 and entitled “SYSTEM ARCHITECTURE FOR ACHIEVING HIGHER SCANNER THROUGHPUT”; on U.S. Provisional Application Ser. No. 61/078,251, filed Jul. 3, 2008 and entitled “HIGH NA CATADIOPTRIC PROJECTION OPTICS FOR IMAGING TWO RETICLES ONTO ONE WAFER”; on U.S. Provisional Application Ser. No. 61/078,254 filed on Jul. 3, 2008 and entitled “X-SCANNING EXPOSURE SYSTEM WITH CONTINUOUS EXPOSURE”; and on U.S. Provisional Application Ser. No. 61/104,477 filed on Oct. 10, 2008. As far as is permitted, the contents of U.S. Provisional Application Ser. Nos. 61/060,411, 61/078,251, 61/078,254 and 61/104,477 are incorporated herein by reference.

BACKGROUND

Exposure apparatuses for semiconductor processing are commonly used to transfer images from a reticle onto a semiconductor wafer during semiconductor processing. A typical exposure apparatus includes an illumination source, a reticle stage assembly that positions a reticle, a projection optical assembly, and a wafer stage assembly that positions a semiconductor wafer.
As illustrated in prior art FIG. 1A, each wafer 1P is typically divided into a plurality of rectangular shaped integrated circuits 2P (sometimes referred to as “sites”). Further, each site 2P has a first site dimension 3P along a first axis (e.g. the X axis), and a second site dimension 4P along a second axis (e.g. the Y axis). Typically, the second site dimension 4P is greater than the first site dimension 3P. For example, a common site 2P has a first site dimension 3P of twenty-six millimeters and a second site dimension 4P of thirty-three millimeters.
There are two kinds of exposure apparatuses that are generally known and currently used. The first kind is commonly referred to as a Stepper lithography system. In a Stepper lithography system, the reticle is fixed (except for slight corrections in position) and the wafer stage assembly moves the wafer to fixed chip sites where the illumination source directs an illumination beam at an entire reticle pattern on the reticle. This causes the entire reticle pattern to be exposed onto one of the chip sites of the wafer at one time. At the time of exposure, the reticle and the wafer are stationary. After the exposure, the wafer is moved (“stepped”) to the next site for subsequent exposure.
The second kind of system is commonly referred to as a Scanner lithography system. In a Scanner lithography system, the reticle stage assembly moves the reticle in one direction along a scan axis 5P (the second axis) concurrently with the wafer stage assembly moving the wafer in one direction along the scan axis 5P during the exposure of a first site 1S. With this system, the illumination beam is slit shaped and illuminates only a portion of the reticle pattern on the reticle. This causes a slit shaped pattern beam 6P to be imaged onto the wafer 1P. This pattern beam 6P exposes only a portion of the first site 1S at a given moment, and the entire reticle pattern is exposed and transferred to the first site 1S over time as the reticle pattern is moved relative to the illumination beam. After exposure of the first site 1S, the wafer 1P is stepped along a step axis 7P (the first axis) and subsequently a second site 2S is scanned while moving the wafer 1P in the opposite direction along the scan axis 5P. With this design, each site 1S, 2S is scanned along the second axis (the longer dimension of the site).
In FIG. 1A, dashed line 11P illustrates an exposure pattern 11P of the first row of sites 2P on the wafer 1P. The exposure pattern 11P comprises a plurality of scanning operations 13P and a plurality of stepping operations 15P, wherein the scanning operations 13P and the stepping operations 15P alternate so that the exposure proceeds in a scan-step-scan-step-scan fashion. As illustrated, and as noted above, the scanning of each site 2P occurs across the second site dimension 4P and the steps between each site 2P occurs along the first axis. This typically results in scanning times and stepping times that are nearly equal to each other.
The throughput capacity of an exposure apparatus used in lithography is often quoted in the number of wafers that can be printed per hour (WPH). Throughput depends on many factors, such as the reticle stage and wafer stage performances, nozzle capabilities (for immersion type exposure apparatuses), and available power for the illumination system.
Additionally, the optical assembly is one of the limiting factors in the performance of a lithography system. More specifically, the optical assembly is thought of as limiting the performance in terms of the resolution, or smallest printable feature. One design tradeoff that is utilized includes keeping a used field of the optical assembly as small as possible to minimize aberrations. For example, FIG. 1B illustrates a field of view 17P (illustrated with a dashed circle) for a prior art optical assembly having a numerical aperture (NA) of 1.30. In this example, the field of view 17P defines a substantially rectangular used field 19P. In the example provided above, to expose a site that is twenty-six millimeters by thirty-three millimeters, the used field 19P has a first field dimension 21P of about twenty-six millimeters along the first axis, and a second field dimension 23P of about five millimeters along the second axis. These measurements are specified at the wafer plane. The corresponding dimensions at the reticle plane are determined by the magnification ratio of the projection optical assembly. For example, in a 4× reduction machine, the reticle dimensions are 4× bigger.
Additionally, in order to further minimize or correct aberrations at such a high NA, the optical assembly is catadioptric. This requires the used field 19P to be off-axis in order to avoid obscurations from the relative surfaces. In one prior art design, the closest edge of the used field 19P has an offset distance 25P of about 2.5 millimeters from an optical axis 27P. This means the diagonal of the point in the used field 19P farthest from the optical axis 27P is 15.01 millimeters, and the field of view 17P has a field diameter of 30.02 millimeters, as explained in Equation 1.
2*√{square root over (13 ²+(5+2.5)²)}=30.02 mm (Equation 1)
Using the specifications for one embodiment of a prior system, where there are 125 chips per wafer, each chip is 16×32 mm, average wafer stage acceleration of 2.5G in the X axis and the Y axis, an average reticle stage acceleration of 10G, and a wafer stage scan velocity of 0.7 m/s, the maximum possible throughput is 246 WPH (assuming no overhead time between wafers).
As is known, there is a never ending search to increase the throughput in exposure apparatuses.

SUMMARY

The present invention is directed to an exposure apparatus for transferring a first mask pattern from a first mask to a substrate. The substrate includes a first site having a first site dimension along a first axis and a second site dimension along a second axis that is perpendicular to the first axis. The second site dimension is larger than the first site dimension.
In one embodiment, the exposure apparatus includes an illumination system, a first mask stage assembly, a substrate stage assembly, and a control system. The illumination system generates a first illumination beam that is directed at the first mask. The first mask stage assembly retains and positions the first mask along the first axis relative to the first illumination beam. The substrate stage assembly retains and positions the substrate along the first axis. The control system controls the illumination system, the first mask stage assembly and the substrate stage assembly so that a portion of the first mask pattern is transferred to a portion of the first site while the first mask stage assembly is moving the first mask along the first axis, and the substrate stage assembly is moving the substrate along the first axis.
With this design, one or more of the sites of the substrate are scanned along their short dimension. As a result thereof, the throughput of the exposure apparatus can be improved.
In certain embodiments, the first illumination beam illuminates the first mask pattern to generate a first pattern beam. In this embodiment, the exposure apparatus further comprises an optical assembly that focuses the first pattern beam on the substrate. Additionally, the optical assembly includes a used field having a first field dimension along the first axis and a second field dimension along the second axis, wherein the first field dimension is smaller than the second field dimension. In one such embodiment, the second field dimension is between approximately thirty millimeters and thirty-five millimeters. Further, in this embodiment, the first field dimension can be between approximately 1.5 mm and 5 mm. Still further, in one embodiment, the first field dimension is shorter than the first site dimension and the second field dimension is equal to or greater than the second site dimension. As provided herein, the design of the optical assembly provided herein allows for the scanning of the sites along their short dimension.
In one embodiment, the exposure apparatus further comprises a second mask stage assembly that retains and positions a second mask. In this embodiment, the illumination system generates a second illumination beam that is directed at the second mask. Additionally, the second illumination beam illuminates a second mask pattern of the second mask to generate a second pattern beam. Further, in this embodiment, the optical assembly focuses the first pattern beam and the second pattern beam on the substrate.
In some embodiments, the substrate may further include a second site, and the control system may control the illumination system, the mask stage assemblies and the substrate stage assembly to transfer an image of the first mask pattern to the first site, and an image of the second mask pattern to the second site. In one such embodiment, the control system controls the substrate stage assembly to continuously move the substrate at a constant velocity along the first axis when transferring the images to the first site and the second site. With this design, multiple sites can be exposed between stepping of the substrate. This improves the throughput of the exposure apparatus.
The present invention is further directed to a method for transferring a first mask pattern from a first mask to a substrate, a method for making an exposure apparatus, and a method of manufacturing a wafer with the exposure apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which:

FIG. 1A is a simplified illustration of a prior art exposure pattern on a wafer;

FIG. 1B is a simplified illustration of a field of view for a prior art optical assembly;

FIG. 2 is a schematic illustration of a first embodiment of an exposure apparatus having features of the present invention;

FIG. 3A is a simplified top illustration of a substrate and an exposure pattern having features of the present invention;

FIG. 3B is a simplified top illustration of a field of view for an optical assembly having features of the present invention;

FIG. 3C is a simplified top illustration of the mask and a portion of the substrate at the beginning of a scanning procedure on a first site;

FIG. 3D is a simplified top illustration of the mask and a portion of the substrate at the end the scanning procedure on the first site;

FIG. 3E is a simplified top illustration of the mask and a portion of the substrate at the beginning of a scanning procedure on a second site;

FIG. 3F is a simplified illustration of an optical assembly having features of the present invention;

FIG. 4 is a schematic illustration of a second embodiment of an exposure apparatus having features of the present invention;

FIG. 5A is a simplified top view of an embodiment of a substrate exposed by the exposure apparatus of FIG. 4;

FIG. 5B is a simplified illustration of a field of view of an embodiment of an optical assembly having features of the present invention;

FIG. 6A is a simplified side view of a first mask, a second mask, an optical assembly, and a substrate at a beginning of an exposure of a first site;

FIG. 6B is a simplified side view of the first mask, the second mask, the optical assembly, and the substrate at a beginning of an exposure of a second site;

FIG. 6C is a simplified side view of the first mask, the second mask, the optical assembly, and the substrate at a beginning of an exposure of a third site;

FIG. 6D is a simplified side view of the first mask, the second mask, the optical assembly, and the substrate at a beginning of an exposure of a fourth site;

FIGS. 7A-7I illustrate one embodiment of the exposure of four sites;

FIGS. 8A-8I illustrate another embodiment of the exposure of four sites;

FIGS. 9A-98I illustrate yet another embodiment of the exposure of four sites;

FIGS. 10A-10D illustrate one embodiment of the exposure of one site;

FIGS. 11A-11D illustrate another embodiment of the exposure of one site;

FIG. 12 is a schematic illustration of the first mask, the second mask, the substrate, and an embodiment of an optical assembly having features of the present invention;

FIG. 13 is a simplified perspective view of portion of another embodiment of an exposure apparatus having features of the present invention;

FIG. 14 is a simplified top view of an embodiment of a substrate exposed utilizing the exposure apparatus illustrated in FIG. 13;

FIG. 15A is a flow chart that outlines a process for manufacturing a device in accordance with the present invention; and

FIG. 15B is a flow chart that outlines device processing in more detail.

DESCRIPTION

FIG. 2 is a schematic illustration of a precision assembly, namely an exposure apparatus 210 that transfers features from a mask 212 to a substrate 214 such as a semiconductor wafer that includes a plurality of sites 315 (illustrated in FIG. 3A). The design of the exposure apparatus 210 can be varied to achieve the desired throughput, and quality and density of the features on the substrate 214. In FIG. 2, the exposure apparatus 210 includes an apparatus frame 216, an illumination system 218 (irradiation apparatus), a projection optical assembly 220, a mask stage assembly 222, a substrate stage assembly 224, a measurement system 226, and a control system 228. Further, the exposure apparatus 210 mounts to a mounting base 230, e.g., the ground, a base, or a floor, or some other supporting structure.
As an overview, in certain embodiments, the projection optical assembly 220 is designed to have a larger field of view 331 (illustrated in FIG. 3B) and/or one or more of the sites 315 of the substrate 214 are scanned along their short dimension. Further, in certain embodiments, the exposure apparatus 410 (illustrated in FIG. 4) is designed to use multiple masks 412 to sequentially expose adjacent sites 315. These features can increase the throughput capabilities of the exposure apparatuses 210, 410.
A number of Figures include an orientation system that illustrates an X axis, a Y axis that is orthogonal to the X axis, and a Z axis that is orthogonal to the X and Y axes. It should be noted that any of these axes can also be referred to as the first, second, and/or third axes.
The exposure apparatus 210 discussed herein is particularly useful as a photolithography system for semiconductor manufacturing that transfers features from a reticle (the mask 212) to a wafer (the substrate 214). However, the exposure apparatus 210 provided herein is not limited to a photolithography system for semiconductor manufacturing. The exposure apparatus 210, for example, can be used as an LCD photolithography system that exposes a liquid crystal display device pattern onto a glass plate or a photolithography system for manufacturing a thin film magnetic head. Further, in certain embodiments, the concepts of the present invention can be utilized in a maskless exposure apparatus.
The apparatus frame 216 is rigid and supports the components of the exposure apparatus 210. The apparatus frame 216 illustrated in FIG. 2 supports the mask stage assembly 222, the projection optical assembly 220, the illumination system 218, and the substrate stage assembly 224 above the mounting base 230.
The illumination system 218 includes an illumination source 232 and an illumination optical assembly 234. The illumination source 232 emits an illumination beam 235 (irradiation) of light energy. The illumination optical assembly 234 guides the illumination beam 235 from the illumination source 232 to near the mask 212. The illumination beam 235 illuminates the mask 212 to generate a pattern beam 236 (e.g. images from the mask 212) that exposes the substrate 214. In one embodiment, the illumination beam 235 is generally slit shaped and illuminates only a portion of the mask 212 at any given moment. Similarly, the pattern beam 236 is generally slit shaped and exposes only a portion of the substrate 214 at any given moment. In the embodiment illustrated in FIG. 2, the mask stage assembly 222 moves the mask 212 back and forth along the first axis (e.g. the X axis) during scanning of the sites 315.
In FIG. 1, the mask 212 is at least partly transparent, and the illumination beam 235 is transmitted through a portion of the mask 212. Alternatively, the mask 212 can be reflective, and the illumination beam 235 can be directed at the mask 212 and reflected off of the mask 212.
The illumination source 232 can be a g-line source (436 nm), an i-line source (365 nm), a KrF excimer laser (248 nm), an ArF excimer laser (193 nm) or an F₂laser (157 nm). Alternatively, the illumination source 232 can generate charged particle beams such as an x-ray or an electron beam. For instance, in the case where an electron beam is used, thermionic emission type lanthanum hexaboride (LaB₆) or tantalum (Ta) can be used as a cathode for an electron gun.
The projection optical assembly 220 projects and/or focuses the pattern beam 236 from the mask 212 to the substrate 214. Depending upon the design of the exposure apparatus 210, the projection optical assembly 220 can magnify or reduce the pattern beam 236. In one non-exclusive embodiment, the projection optical assembly 220 reduces the pattern beam 236 by a reduction factor of four. As a result thereof, during the exposure of a site 315, the mask stage assembly 222 must move the mask 212 a distance that is four times greater than a distance in which the substrate stage assembly 224 moves the substrate 214. Stated in another fashion, if the projection optical assembly 220 has a reduction factor of 4, the substrate 214 is moved at a rate that is one fourth that of the mask 212.
In certain embodiments, as discussed in more detail below, the projection optical assembly 220 includes a plurality of optical elements 220A (illustrated in phantom in FIG. 2) that are designed and arranged so that the projection optical assembly 220 will have a relatively large field of view 331 so that one or more of the sites 315 of the substrate 214 can be scanned along their short dimension. A discussion of possible fields of view 331 for the projection optical assembly 220 is described in more detail below.
The mask stage assembly 222 holds and positions the mask 212 relative to the projection optical assembly 220 and the substrate 214. The mask stage assembly 222 can include (i) a mask stage 237 having a chuck (not shown) for holding the mask 212, and (ii) a mask stage mover assembly 238 that moves and positions the mask stage 237 and the mask 212. For example, the mask stage mover assembly 238 can move the mask stage 237 and the mask 212 along the Y axis, along the X axis, and about the Z axis. Alternatively, for example, the mask stage mover assembly 238 could be designed to move the mask stage 237 and the mask 212 with more than three degrees of freedom, or less than three degrees of freedom. For example, the mask stage mover assembly 238 can include one or more linear motors, rotary motors, planar motors, voice coil actuators, or other type of actuators. In the embodiment illustrated in FIG. 2, the mask stage mover assembly 238 moves the mask 212 along the first axis (e.g. the X axis) during scanning of the sites 315.
Somewhat similarly, the substrate stage assembly 224 holds and positions the substrate 214 with respect to the pattern beam 236. The substrate stage assembly 224 can include (i) a substrate stage 240 having a chuck (not shown) for holding the substrate 214, and (ii) a substrate stage mover assembly 242 that moves and positions the substrate stage 240 and the substrate 214. For example, the substrate stage mover assembly 242 can move the substrate stage 240 and the substrate 214 along the Y axis, along the X axis, and about the Z axis. Alternatively, for example, the substrate stage mover assembly 242 could be designed to move the substrate stage 240 and the substrate 214 with more than three degrees of freedom, or less than three degrees of freedom. For example, the substrate stage mover assembly 242 can include one or more linear motors, rotary motors, planar motors, voice coil actuators, or other type of actuators. In the embodiment illustrated in FIG. 2, the substrate stage mover assembly 242 moves the substrate 214 along the first axis (e.g. the X axis) during scanning of the sites 315 and moves the substrate 214 along the second axis (e.g. the Y axis) while stepping in between scanning of the sites 315.
The measurement system 226 monitors movement of the mask 212 and the substrate 214 relative to the projection optical assembly 220 or some other reference. With this information, the control system 228 can control the mask stage assembly 222 to precisely position the mask 212 and the substrate stage assembly 224 to precisely position the substrate 214. For example, the measurement system 226 can utilize multiple laser interferometers, encoders, and/or other measuring devices.
The control system 228 is connected to the illumination system 218, the mask stage assembly 222, the substrate stage assembly 224, and the measurement system 226. The control system 228 receives information from the measurement system 226, and controls the illumination system 218 and the stage assemblies 222, 224 to precisely position the mask 212 and the substrate 214 and expose the sites 315. The control system 228 can include one or more processors and circuits. In FIG. 2, the control system 228 is illustrated as a single unit. It should be noted that in alternative embodiments the control system 228 can be designed with multiple, spaced apart controllers.
FIG. 3A is a simplified top view of one non-exclusive embodiment of a substrate 214 that has been processed with the exposure apparatus 210 of FIG. 2. In this embodiment, the substrate 214 is a generally disk shaped, thin slice of semiconductor material, e.g. a semiconductor wafer, that serves as a substrate for photolithographic patterning. Typically, the disk shaped substrate 214 is divided into a plurality of rectangular shaped sites 315 (e.g. chips) that are organized into a plurality of rows (along the X axis) and columns (along the Y axis). As used herein, the term “site” shall mean an area on the substrate 214 to which the entire or a portion of the mask pattern 346 (illustrated in FIG. 3C) has been transferred. For example, for a semiconductor wafer, each site 315 is one or more integrated circuits that include a number of connected circuit elements that were transferred to the substrate 214 by the exposure apparatus 210 of FIG. 2. In this example, each site 315 contains one or more integral die piece(s) that can be sliced from the wafer.
In one embodiment, each site 315 is generally rectangular shaped and has a first site dimension 348 (measured along the X axis) that is less than a second site dimension 350 (measured along the Y axis). In one non-exclusive embodiment, each site 315 has a first site dimension 348 of approximately twenty-six (26) millimeters, and a second site dimension 350 of approximately thirty-three (33) millimeters. Alternatively, for example, each site 315 can have a first site dimension 348 that is greater than or less than twenty-six (26) millimeters, and a second site dimension 350 that is greater than or less than thirty-three (33) millimeters. For example, each site 315 can have a first site dimension 348 of approximately sixteen (16) millimeters, and a second site dimension 350 of approximately thirty-two (32) millimeters.
The size of the substrate 214 and the number of sites 315 on the substrate 214 can be varied. For example, the substrate 214 can have a diameter of approximately three hundred millimeters. Alternatively, the substrate 214 can have a diameter that is greater than or less than three hundred millimeters and/or the substrate 214 can have a shape that is different than disk shaped (e.g. rectangular shaped). For example, the substrate 214 can be circularly shaped with a diameter approximately four hundred fifty millimeters.
Further, for simplicity, in the embodiment illustrated in FIG. 3A, the substrate 214 is illustrated as having fifteen separate sites 315. Alternatively, for example, the substrate 214 can be separated into greater than or fewer than fifteen sites 315.
In FIG. 3A, the sites 315 have been labeled “1” through “15” (one through fifteen). In this example, (i) the sites 315 labeled “1” through “3” are aligned in a first column along the Y axis; (ii) the sites 315 labeled “4” through “6” are aligned in a second column along the Y axis; (iii) the sites 315 labeled “7” through “9” are aligned in a third column along the Y axis; (iv) the sites 315 labeled “10” through “12” are aligned in a fourth column along the Y axis; and (v) the sites 315 labeled “13” through “15” are aligned in a fifth column along the Y axis. Additionally, the labels “1” through “15” represent one non-exclusive embodiment of a sequence in which the mask pattern 346 can be transferred to the sites 315 on the substrate 214. More specifically, as provided herein, the exposure apparatus 210 can first transfer the mask pattern 346 to the site 315 labeled “1” (sometimes referred to as the “first site”). Next, the exposure apparatus 210 can move the mask 212 (illustrated in FIG. 2) and the substrate 214, and transfer the mask pattern 346 to the site 315 labeled “2” (sometimes referred to as the “second site”). Subsequently, and sequentially, the exposure apparatus 210 can move the mask 212 and the substrate 214 to sequentially transfer the mask pattern 346 to the sites 315 labeled “3”, “4”, “5”, . . . and “15”.
Moreover, FIG. 3A includes an exposure pattern 352 (illustrated with a dashed line) which further illustrates the order in which the mask pattern 346 is transferred to sites “1” through “3” in the first column. In this example, (i) the sites 315 labeled “1” through “3” are sequentially exposed as the substrate 214 is moved in a weaving (boustrophedonic) fashion and the mask 212 is moved back and forth. More specifically, the exposure pattern 352 comprises a plurality of scanning operations 354 and a plurality of stepping operations 356, wherein the scanning operations 354 and the stepping operations 356 alternate so that the exposure proceeds in a scan-step-scan-step-scan fashion. As provided herein, the scanning 354 of each site 315 occurs as the substrate 214 is moved along a scan axis 358 (i.e., the X axis) across the first site dimension 348, and the stepping 356 in between exposures of sites 315 occurs as the substrate 214 is moved along a step axis 360 (i.e., the Y axis).
It should be noted that with the design illustrated in FIG. 3A, the scanning operations 354 occur while the substrate 214 is moved along the first site dimension 348 and stepping operations 356 occur while the substrate 214 is moved along the second site dimension 350. This results in shorter scanning times and longer stepping times compared to the prior art.
It should also be noted that in this example, the site 315 that is exposed first and the order in which the columns are exposed can be different than that illustrated in FIG. 3A. Further, the site 315 that is first exposed can be located away from the edge of the substrate 214
Additionally, FIG. 3A illustrates the pattern beam 236 that is directed at the first site “1” on the substrate 214. The pattern beam 236 is discussed in more detail with reference to FIGS. 3C-3E.
FIG. 3B is a simplified illustration of one embodiment of a field of view 331 (illustrated with a dashed circle) of the projection optical assembly 220 (illustrated in FIG. 2). As used herein, the term field of view 331 shall mean the maximum image area over which the projection optical assembly 220 can provide a sufficiently accurate image of the mask pattern. As provided herein, in certain embodiments, the field of view 331 of the projection optical assembly 220 must be relatively large in order to transfer a relatively large pattern beam 236 (illustrated in FIG. 3A) to the site 315.
In one embodiment, the field of view 331 defines a rectangular shaped used field 362 (illustrated with a box with “X”'s) that includes a first field dimension 364 that is measured along the first axis (the X axis) and a second field dimension 366 that is measured along the second axis (the Y axis). In this embodiment, the second field dimension 366 is larger than the first field dimension 366.
In certain embodiments, the projection optical assembly 220 is designed so that the first field dimension 364 is less than the first site dimension 348 (illustrated in FIG. 3A) and the second field dimension 366 is equal to or greater than the second site dimension 350.
In one non-exclusive example, each site 315 has a first site dimension 348 of twenty-six (26) millimeters and a second site dimension 350 of thirty-three (33) millimeters. In this example, the second field dimension 366 can be approximately thirty-three (33) millimeters, and the first field dimension 364 is less than twenty-six (26) millimeters. As non-exclusive examples, the first field dimension 364 can be approximately 2, 3, 4, 5, or 5.5 millimeters. Further, as non-exclusive examples, the second field dimension 366 can be approximately 29, 30, 31, 32, 34, or 35 millimeters
Further, comparing prior art FIG. 1B and FIG. 3B, the used field 362 of FIG. 3B has been rotated by approximately 90 degrees from the orientation of the used field 19P in the prior art (as illustrated in FIG. 1B). In one non-exclusive embodiment, in order to minimize the impact of the orientation change, the edge of the used field 362 can be moved closer to an optical axis 368 of the projection optical assembly 220. In this embodiment, for example, the offset distance 368A is about 1.25 millimeters, instead of the prior art design of 2.50 millimeters illustrated in FIG. 1B. Further, the first field dimension 364 of the used field 362 is less than the prior art design described above. The resulting maximum field point is now 16.92 millimeters for a field diameter 368B of 33.84 millimeters as calculated in Equation 2.
$\begin{matrix} 2 * \sqrt{{16.5}^{2} + {(2.5 + 1.25)}^{2}} = 33.84 mm (33 mm field height) & (Equation 2) \end{matrix}$
Additionally, it is important to look at the approximate gain in throughput obtained by increasing the size of the used field 362 of the projection optical assembly 220 and changing the scan direction from across the second site dimension 350 to across the first site dimension 348.
More specifically, utilizing a slightly larger used field 362 size of 33 millimeters by 2.5 millimeters for optical assembly 220, scanning the used field 362 across the first site dimension 348 instead of across the second site dimension 350, with an average wafer stage acceleration of 2.5G in X axis and Y axis, an average mask 212 acceleration of 10G, and a substrate 214 scan velocity of 0.7 m/s, the maximum throughput is 274 wafers per hour. The gain is 28 WPH, or an 11.5% gain in throughput over the prior art described in the background. Alternatively, in certain embodiments, the idea of scanning the used field 362 across the first field dimension 364 could be used to decrease the requirements for acceleration and maximum scanning velocity of the substrate stage assembly 224 (illustrated in FIG. 2) and/or the mask stage assembly 222 (illustrated in FIG. 2), while still maintaining the same or better throughput than is possible in the prior art.
FIG. 3C is a simplified top illustration of the mask 212 and a portion of the substrate 214 in a side-by-side arrangement, at the start of an exposure of the first site 1 (illustrated as a box). It should be noted that the components of the exposure apparatus 210 (illustrated in FIG. 2) are not shown in FIGS. 3C-3E for clarity. Further, it should also be noted that the mask 212 and the substrate 214 are shown in a side-by-side arrangement during exposure and that FIGS. 3C-3E are only illustrated in this configuration so that the relative positions of these components can be better understood. Additionally, in these Figures, the mask pattern 346 is illustrated as being approximately the same size as each site 315. However, in the event that the projection optical assembly 220 has a reduction factor of 4, the mask pattern 346 can be four times larger than the size of each site 315. Moreover, FIG. 3C also illustrates at least a portion of sites 2 through 9. In this embodiment, each site 315 includes a site left side 315A, an opposed site right side 315B, and a site center 315C (only one is illustrated with a FIG. 3C illustrates that the mask 212 includes the mask pattern 346 (illustrated as a box) that includes the features that are to be transferred to the substrate 214. In this embodiment, the mask pattern 346 includes a pattern left side 346A, and opposed pattern right side 346B, and a pattern center 346C (illustrated as with a “+”).
At the start of exposure of the first site 1, the control system 228 (illustrated in FIG. 2) controls the illumination system 218 (illustrated in FIG. 2) to generate the slit shaped illumination beam 235 (illustrated as “o”'s) that is directed at the mask 212, and controls the mask stage assembly 222 (illustrated in FIG. 2) to position the mask 212 so that the mask pattern 346 is illuminated near the pattern left side 346A. This causes the resulting pattern beam 236 (illustrated as “\”'s) to be directed at a corresponding portion of the first site 1. In the illustrations, the left side of the mask pattern area corresponds to the left side of the substrate site. Depending on the optical design, however, the image may be reversed, so the right side of the mask pattern area corresponds to the left side of the substrate site.
At the beginning of the exposure of the first site 1, (i) the pattern center 346C is located at a first mask position, which is referenced as Xm1 along the scan axis 358 and Ym1 along the step axis 360, and (ii) the site center 315C of the first site 1 is located at a site first position, which is referenced as Xs1 along the scan axis 358 and Ys1 along the step axis 360.
Further, at the beginning of the exposure, the control system 228 (illustrated in FIG. 2) (i) controls the mask stage assembly 222 so that the mask 212 is being moved at a constant velocity in a first scan direction 370A (from right to left in FIG. 3A) along the scan axis 358 (the X axis), and (ii) controls the substrate stage assembly 224 (illustrated in FIG. 2) so that the substrate 214 is also being moved at a constant velocity in the first scan direction 370A along the scan axis 358. With the present design, in certain embodiments, both the mask 212 and the substrate 214 are moved synchronously in the same scan direction 370A. Further, for example, if the projection optical assembly 220 (illustrated in FIG. 2) has a reduction factor of four, the mask 212 is moved at a rate that is four times greater than that of the substrate 214. Alternatively, the mask 212 and substrate 214 can be moved in opposite directions along the scan axis 358 during scanning of the sites 315.
Additionally, as illustrated in FIG. 3C, the pattern beam 236 is generally rectangular slit shaped and includes a first beam dimension 372 along the first axis (the X axis) and a second beam dimension 374 along the second axis (the Y axis). In this embodiment, the second beam dimension 374 is larger than the first beam dimension 372. In certain embodiments, the exposure apparatus 210 (illustrated in FIG. 2) is designed so that the first beam dimension 372 is less than the first site dimension 348 (illustrated in FIG. 3A) and the second beam dimension 374 is equal to the second site dimension 350 (illustrated in FIG. 3A). In one non-exclusive example, each site 315 has a first site dimension 348 of twenty-six (26) millimeters and a second site dimension 350 of thirty-three (33) millimeters. In this example, the second beam dimension 374 can be approximately thirty-three (33) millimeters, and the first beam dimension 372 is less than twenty-six (26) millimeters. As non-exclusive examples, the first beam dimension 372 can be approximately 2, 3, 4, 5, or 5.5 millimeters. Alternatively, for example, the second beam dimension 374 can be approximately 29, 30, 31, 32, 34, or 35 millimeters.
FIG. 3D is a simplified top illustration of the mask 212 and a portion of the substrate 214 in a side-by-side arrangement, at the end of the exposure of the first site 1. At this time, the control system 228 (illustrated in FIG. 2) controls the illumination system 218 (illustrated in FIG. 2) to generate the slit shaped illumination beam 235 (illustrated as “o”'s) that is directed at the mask 212, and controls the mask stage assembly 222 (illustrated in FIG. 2) to position the mask 212 so that the mask pattern 346 is illuminated near the pattern right side 346B. This causes the resulting pattern beam 236 (illustrated as “\”'s) to be directed at a portion of the first site 1.
At the end of the exposure of the first site 1, (i) the pattern center 346C is located at a second mask position, which is referenced as Xm2 along the scan axis 358 and Ym1 along the step axis 360, and (ii) the site center 315C of the first site 1 is located at a site second position, which is referenced as Xs2 along the scan axis 358 and Ys1 along the step axis 360.
It should be noted that (i) the difference between the first mask position Xm1 and the second mask position Xm2 along the scan axis 358 is referred to herein as a mask exposure distance 376, and (ii) the difference between the first substrate position Xs1 and the second substrate position Xs2 along the scan axis 358 is referred to herein as a site exposure distance 378. In this example, (i) the mask exposure distance 376 is the distance in which the mask 212 is moved along the scan axis 358 during the exposure (i.e., the scanning operation 354 as illustrated in FIG. 3A) of the first site 1, and (ii) the site exposure distance 378 is the distance in which the substrate 314 is moved along the scan axis 358 during the exposure of the first site 1.
For clarity, in FIG. 3D, the mask exposure distance 376 is illustrated as being equal to the site exposure distance 378. Alternatively, in the event the projection optical assembly 220 (illustrated in FIG. 1) has a reduction factor of four, the mask exposure distance 376 is four times larger than the site exposure distance 378.
Referring to FIGS. 3C and 3D, it should also be noted that the entire mask pattern 346 is scanned to the first site 1 during movement of the mask 212 the mask exposure distance 376. Additionally, the exposure of the first site 1 is halted once the pattern beam 236 is directed at the pattern right side 346B.
Further, it should be noted that during the exposure of the sites 315 (i.e., during the scanning operations 354), the control system 228 controls the mask stage assembly 222 so that the mask 212 is approximately not moved along the step axis 360 (the Y axis), and the control system 228 controls the substrate stage assembly 224 (illustrated in FIG. 2) so that the substrate 214 is approximately not moved along the step axis 360 (the Y axis). Moreover, during scanning, both the mask 212 and the substrate 214 are moved at a constant velocity along the scan axis 358.
FIGS. 3E is a simplified top illustration of the mask 212 and a portion of the substrate 214 in a side-by-side arrangement, at the start of an exposure of the second site 2. At this time, the control system 228 (illustrated in FIG. 2) controls the illumination system 218 (illustrated in FIG. 2) to generate the slit shaped illumination beam 235 (illustrated as “o”'s) that is directed at the mask 212, and controls the mask stage assembly 222 (illustrated in FIG. 2) to position the mask 212 so that the mask pattern 346 is illuminated near the pattern right side 346B. This causes the resulting pattern beam 236 (illustrated as “\”'s) to be directed at a corresponding portion of the second site 2.
At the beginning of the exposure of the second site 2, (i) the pattern center 346C is again located at the second mask position, which is referenced as Xm2 along the scan axis 358 and Ym1 along the step axis 360, and (ii) the site center 315C of the first site 1 is located at a site third position, which is referenced as Xs2 along the scan axis 358 and Ys2 along the step axis 360.
Basically, in between exposures (i.e., during the stepping operations 356 as illustrated in FIG. 3A), (i) the substrate 214 is stepped with the substrate stage assembly 224 (illustrated in FIG. 2) so that the second site 2 is being moved towards the field of view 331 (illustrated in FIG. 3B) of the projection optical assembly 220 (illustrated in FIG. 2), and (ii) the position of the mask pattern 346 is reset along the scan axis 358 to the second mask position Xm2 with the mask stage assembly 222 (illustrated in FIG. 2). It should be noted that the mask pattern 346 is moved past the second mask position Xm2 after the exposure because the mask 212 is moved at a constant velocity during the entire exposure and the mask 212 must be decelerated after the exposure. The mask is subsequently accelerated back toward the second mask position Xm2 prior to the next exposure, so that the mask 212 can again be moved at a constant velocity from the second mask position Xm2 to the first mask position Xm1 during the subsequent exposure of the second site 2.
It should also be noted that the difference between the site first position Ys1 and the site third position Ys2 along the step axis 358 is referred to herein as a site step distance 380. In this example, the site step distance 380 is the distance in which the substrate 314 is moved along the step axis 360 between the exposure of the first site 1 and the exposure of the second site 2 (i.e., during the stepping operation 356).
Further, at the beginning of the exposure, the control system 228 (illustrated in FIG. 2) (i) controls the mask stage assembly 222 so that the mask 212 is being moved at a constant velocity in a second scan direction 370B (from left to right in FIG. 3A) along the scan axis 358 (the X axis) from the second mask position Xm2 back toward the first mask position Xm1, and (ii) controls the substrate stage assembly 224 (illustrated in FIG. 2) so that the substrate 214 is also being moved at a constant velocity in the second scan direction 370B along the scan axis 358 from Xs2 back toward Xs1. With the present design, in certain embodiments, both the mask 212 and the substrate 214 are moved synchronously in the same scan direction 370B. Further, for example, if the projection optical assembly 220 (illustrated in FIG. 2) has a reduction factor of four, the mask 212 is moved at a rate that is four times greater than that of the substrate 214. Alternatively, as noted above, the mask 212 and substrate 214 can be moved in opposite directions along the scan axis 358 during scanning of the sites 315.
FIG. 3F is a simplified illustration of one non-exclusive embodiment of the projection optical assembly 220. In this embodiment, the projection optical assembly 220 includes the plurality of spaced apart optical elements 220A and an optical housing 382A. In this embodiment, the projection optical assembly 220 has an optical axis 382B and the optical elements 220A are aligned along the optical axis 382B.
As provided herein, the design, positioning, and number of optical elements 220A can be varied to achieve the relatively large field of view 331 (illustrated in FIG. 3B) and described above so that one or more of the sites 315 (illustrated in FIG. 3A) of the substrate 214 (illustrated in FIG. 3A) can be scanned along their short dimension. In FIG. 3F, the projection optical assembly 220 is illustrated as having eleven optical elements 220A. Alternatively, the projection optical assembly 220 can be designed with greater or fewer than eleven optical elements 220A. As provided herein, the number of optical elements 220A can be greater than what is typical utilized in prior art projection optical assemblies to cancel off-axis aberrations. In FIG. 3F, the optical elements 220A are aligned along the common optical axis 382B. Alternatively, the optical path can be folded to allow for the use of additional optical elements 220A for aberration correction without increasing the distance between the mask and the substrate.
In one embodiment, one or more of the optical elements 220A is a lens that is made of high quality fused silica (SiO2). Alternatively, one or more of the optical elements 220A can be made of another material.
In one embodiment, in order to achieve a larger field of view 331, one or more of the optical elements 220A can have an element diameter 320B that is greater than approximately three hundred fifty millimeters (350 mm). For example, in alternative non-exclusive embodiments, one or more of the optical elements 220A can have an element diameter 320B that is greater than approximately 360, 370, 375, 380, 385, or 390 millimeters.
Further, in order to achieve a larger field of view 331 with less off-axis aberrations, a separation distance 320C between a top of an uppermost element 320U of the projection optical assembly 220 and a bottom of a lowermost element 320L can be greater than approximately 1.4 meters. For example, in alternative non-exclusive embodiments, the separation distance 320C can be greater than approximately 1.5, 1.6, 1.7, 1.8, 1.9, or 2 meters for a NA=1.3 system.
FIG. 4 is a schematic illustration of a second embodiment of an exposure apparatus 410 having features of the present invention. In FIG. 4, the exposure apparatus 410 includes an apparatus frame 416, an illumination system 418, an optical assembly 420, a first mask stage assembly 422A, a second mask stage assembly 422B, a substrate stage assembly 424, a measurement system 426, and a control system 428. Many of these components are similar in design to the corresponding similarly named components described above and illustrated in FIG. 2.
In this embodiment, the exposure apparatus 410 utilizes multiple masks 412A, 412B to transfer images to a substrate 414 that includes a plurality of sites 415. With this embodiment, in certain embodiments, the masks 412A, 412B are substantially identical in design, and at least two adjacent sites 415 on the substrate 414 can be sequentially exposed without stopping the substrate 414 and without changing the movement direction of substrate 414. Stated in another fashion, at least two sites 415 can be scanned without stepping the substrate 414. This allows for higher overall throughput for the exposure apparatus 410.
Further, in this embodiment, the exposure apparatus 410 is a scanning type photolithography system (i) that first exposes a first mask pattern 429A from the first mask 412A onto one of the sites 415 of the substrate 414 while the first mask 412A and the substrate 414 are moving synchronously, and (ii) that subsequently exposes a second mask pattern 429B from the second mask 412B onto an adjacent site 415 on the substrate 414 while the second mask 412B and the substrate 414 are moving synchronously. Alternatively, the masks 412A, 412B can be different in design and the exposure apparatus 410 can be used to scan both the first mask pattern 429A and the second mask pattern 429B onto the same site 415, simultaneously or at different times.
An additional discussion of a multiple mask exposure system is disclosed in concurrently filed application Ser. No. ______, entitled “EXPOSURE APPARATUS THAT UTILIZES MULTIPLE MASKS” (PA1017-00/4990/Roeder Ref. No.11269.156), which is assigned to the assignee of the present invention, and is incorporated by reference herein as far as permitted.
An additional discussion regarding another type of exposure apparatus is disclosed in concurrently filed application Ser. No. ______, entitled “EXPOSURE APPARATUS WITH SCANNING ILLUMINATION BEAM” (PAO1003-00/04982/Roeder Ref. No. 11269.177), which is assigned to the assignee of the present invention, and is incorporated by reference herein as far as permitted.
The illumination system 418 generates a first illumination beam 435A (irradiation) of light energy that is selectively directed at the first mask 412A, and a second illumination beam 435B (irradiation) of light energy that is selectively directed at the second mask 412B. In certain embodiments, the illumination system 418 generates both illumination beams 435A, 435B at the same time. Alternatively, in certain designs, the illumination system 418 will sequentially generate the illumination beams 435A, 435B during the sequential exposure of the sites 415.
In one embodiment, the illumination system 418 includes (i) a first illumination source 432A that emits the first illumination beam 435A; (ii) a first illumination optical assembly 434A that guides the first illumination beam 435A from the first illumination source 432A to near the first mask 412A; (iii) a second illumination source 432B that emits the second illumination beam 435B; and (iv) a second illumination optical assembly 434B that guides the second illumination beam 435B from the second illumination source 432B to near the second mask 412B. Alternatively, the illumination system 418 can be designed with a single illumination source that generates an illumination beam that is split or selectively redirected to create the multiple separate illumination beams 435A, 435B.
The first illumination beam 435A illuminates the first mask 412A to generate a first pattern beam 436A (e.g. images from the first mask 412A) that exposes the substrate 414. Similarly, the second illumination beam 435B illuminates the second mask 412B to generate a second pattern beam 436B (e.g. images from the second mask 412B) that exposes the substrate 414.
The optical assembly 420 projects and/or focuses the first pattern beam 436A and the second pattern beam 436B onto the substrate 414. In the embodiment illustrated in FIG. 4, the optical assembly 420 includes (i) a first optical inlet 421A that receives the first pattern beam 436A, (ii) a second optical inlet 421B that receives the second pattern beam 436B, and (iii) an optical outlet 421C that directs both pattern beams 436A, 436B at the substrate 414. Further, in this embodiment, (i) the first optical inlet 421A includes a first inlet axis 421D, (ii) the second optical inlet 421B includes a second inlet axis 421E, and (iii) the optical outlet 421C includes an outlet axis 421F. The optical assembly 420 is described in more detail below.
The first mask stage assembly 422A holds and positions the first mask 412A relative to the optical assembly 420 and the substrate 414. Similarly, the second mask stage assembly 422B holds and positions the second mask 412B relative to the optical assembly 420 and the substrate 414. Further, the substrate stage assembly 424 holds and positions the substrate 414 with respect to the pattern beams 436A, 436B. The stage assemblies 422A, 422B, 424 can be similar in design to the corresponding components described above with reference to FIG. 2.
The control system 428 receives information from the measurement system 426 and controls the stage assemblies 422A, 422B, 424 to precisely position the masks 412A, 412B and the substrate 414. Further, the control system 428 can control the operation of the illumination system 418 to selectively and independently generate the illumination beams 435A, 435B.
FIG. 5A is a simplified top view of one non-exclusive embodiment of a substrate 414 that can be exposed with the exposure apparatus 410 described above. The design of the substrate 414 is similar to the substrate 214 described above and illustrated in FIG. 3A. However, in FIG. 5A, the order in which the sites 415 are exposed is different. More specifically, two sites 415 are scanned along the X axis (e.g. the short dimension of the sites 415) before being stepped along the Y axis.
In this embodiment, the substrate 414 is illustrated as having thirty-two separate sites 415, with each site 415 having a first site dimension 548 (measured along the X axis) that is less than a second site dimension 550 (measured along the Y axis). In one non-exclusive embodiment, each site 415 has a first site dimension 548 of approximately twenty-six (26) millimeters, and a second site dimension 550 of approximately thirty-three (33) millimeters.
In FIG. 5A, the sites 415 have been labeled “1” through “32” (one through thirty-two). In this example, the labels “1” through “32” represent one non-exclusive embodiment of the sequence in which the mask patterns 436A, 436B can be transferred to the sites 415 on the substrate 414. More specifically, as provided herein, the exposure apparatus 410 can transfer the first mask pattern 429A from the first mask 412A to the site 415 labeled “1” (sometimes referred to as the “first site”). Next, the exposure apparatus 410 can transfer the second mask pattern 429B from the second mask 412B to the site 415 labeled “2” (sometimes referred to as the “second site”). Subsequently, the exposure apparatus 410 can transfer the second mask pattern 429B from the second mask 412B to the site 415 labeled “3” (sometimes referred to as the “third site”). Next, the exposure apparatus 410 can transfer the first mask pattern 429A from the first mask 412A to the site 415 labeled “4” (sometimes referred to as the “fourth site”). Subsequently, the exposure apparatus 410 can continue repeating the sequencing of the transferring of the first mask pattern 429A and the second mask pattern 429B (i.e., in a first, second, second, first sequence) to the sites 415 labeled “6”, “7”, “8”, . . . and “32”. In an alternative embodiment, the exposure apparatus 410 can alternate between transferring the first mask pattern 429A and the second mask pattern 429B to the sites 415 labeled “1”, “2”, “3”, “4”, “5”, . . . and “32” (i.e., the first mask pattern 429A is transferred to all the odd numbered sites 415, and the second mask pattern 429B is transferred to all the even numbered sites 415).
Moreover, FIG. 5A includes an exposure pattern 552A (illustrated with a dashed line) which further illustrates the order in which the mask patterns 429A, 429B are transferred to sites 415. In this example, the exposure pattern 552A again includes a plurality of scanning operations 552B and a plurality of stepping operations 552C, wherein the scanning operations 552B and the stepping operations 552C alternate so that the exposure proceeds in a scan-step-scan-step-scan fashion. In this embodiment, the scanning 552B occurs as the substrate 414 is moved along a scan axis 558 (the X axis), and the stepping 552C occurs as the substrate 414 is moved along a step axis 560 (the Y axis).
It should be noted that with the use of multiple masks 412A, 412B (illustrated in FIG. 4), two adjacent sites 415 (e.g. 1 and 2) can be scanned sequentially while moving the substrate 414 at a constant velocity along the scan axis 558. As a result thereof, the substrate 414 does not have to be stepped and reversed in direction between the exposures of the sites 415. Instead, for the embodiment illustrated in FIG. 5A, the substrate 414 is only stepped between the exposure of pairs of adjacent sites 415 aligned on the scan axis 558. Stated in another fashion, with the present design, there is one stepping motion for every two sites 415 scanned. This results in fewer steps and significantly improved throughput from the exposure apparatus 410.
It should be noted that in this example, the site 415 that is exposed first and the order in which the sites 415 are exposed can be different than that illustrated in FIG. 5A. Further, the site 415 that is first exposed can be located away from the edge of the substrate 414.
FIG. 5B is a simplified illustration of one embodiment of a field of view 531 (illustrated with a dashed circle) of the optical assembly 420 (illustrated in FIG. 4). As provided herein, in certain embodiments, the field of view 531 of the optical assembly 420 must be relatively large in order to transfer a relatively large pattern beam 436A, 436B (illustrated in FIG. 4) to the site 415 (illustrated in FIG. 5A).
In one embodiment, the field of view 531 defines (i) a first used field 562A (illustrated as a box with solid lines) in which the first pattern beam 436A (illustrated in FIG. 4) exits the optical assembly 420, and (ii) and a spaced apart second used field 562B (illustrated as a box with dashed lines) in which the second pattern beam 436B (illustrated in FIG. 4) exits the optical assembly 420. In one embodiment, the first used field 562A and the second used field 562B are substantially similar in shape and size. As illustrated, the first used field 562A has a rectangular shape that includes a first field dimension 564 that is measured along the first axis (the X axis) and a second field dimension 566 that is measured along the second axis (the Y axis). In this embodiment, the second field dimension 566 is larger than the first field dimension 564.
In certain embodiments, the optical assembly 420 is designed so that the first field dimension 564 is less than the first site dimension 548 (illustrated in FIG. 5A) and the second field dimension 566 is equal to the second site dimension 550 (illustrated in FIG. 5A). In one non-exclusive example, each site 415 has a first site dimension 548 of twenty-six (26) millimeters and a second site dimension 550 of thirty-three (33) millimeters. In this example, the second field dimension 566 can be approximately thirty-three (33) millimeters, and the first field dimension 564 is less than twenty-six (26) millimeters. As non-exclusive examples, the first field dimension 564 can be approximately 2, 2.5, or 3 millimeters.
In one embodiment, the optical assembly 420 has a numerical aperture (NA) of at least approximately 1.30. In order to minimize or correct aberrations of the optical assembly 420 at such a high NA, the optical assembly 16 can be catadioptric. In one embodiment, the used fields 562A, 562B are off-axis in order to avoid obscurations from the relative surfaces. Stated in another fashion, in the embodiment illustrated in FIG. 5B, (i) the first used field 562A is offset from an optical axis 568 of the optical assembly 420 a first offset distance 568A, (ii) the second used field 562B is offset from the optical axis 568 a second offset distance 568B, and (iii) the first used field 562A and the second used field 562B are spaced apart a separation distance 568C. Moreover, the used fields 562A, 562B are positioned on opposite sides of the optical axis 568, and the used fields 562A, 562B are substantially parallel to each other. In one non-exclusive embodiment, each offset distance 568A, 568B is approximately 2.5 millimeters, and the separation distance 568C is approximately 5 millimeters. Alternatively, the offset distances 568A, 568B can be greater than or less than 2.5 millimeters.
FIGS. 6A-6D further illustrate one non-exclusive embodiment of how a substrate 414 can be exposed utilizing the exposure apparatus 410 illustrated in FIG. 4. More specifically, FIG. 6A is a simplified side view of the first mask 412A, the second mask 412B, the optical assembly 420, and the substrate 414 at a beginning of an exposure of a first site 1. At the start of exposure of the first site 1, the control system 428 (illustrated in FIG. 4) controls the illumination system 418 (illustrated in FIG. 4) to generate the slit shaped first illumination beam 435A that is directed at the first mask 412A, and controls the first mask stage assembly 422A (illustrated in FIG. 4) to position the first mask 412A so that the first mask pattern 429A is illuminated near a right side of the pattern 429A. This causes a resulting first pattern beam 436A to be directed by the optical assembly 420 at the right side of the first site 1.
Additionally, as illustrated in FIG. 6A, the first pattern beam 436A is initially directed toward the first optical inlet 421A along the first inlet axis 421D. The first pattern beam 436A is subsequently redirected and focused within the optical assembly 420 until the first pattern beam 436A is ultimately directed by the optical assembly 420 from the optical outlet 421C offset from the outlet axis 421F. More particularly, the first pattern beam 436A is directed by the optical assembly 420 through the optical outlet 421C toward a right side of the first site 1.
Further, at the beginning of the exposure of the first site 1, the control system 428 (i) controls the first mask stage assembly 422A so that the first mask 412A is being moved at a constant velocity in a first scan direction 558A (from left to right in FIG. 6A) along the scan axis 558 (the X axis), and (ii) controls the substrate stage assembly 424 (illustrated in FIG. 4) so that the substrate 414 is also being moved at a constant velocity in the first scan direction 558A along the scan axis 558. With the present design, in certain embodiments, both the first mask 412A and the substrate 412 are moved synchronously in the same scan direction 558A. Further, for example, if the optical assembly 420 has a reduction factor of four, the first mask 412A is moved at a rate that is four times greater than that of the substrate 414. Alternatively, the first mask 412A and the substrate 414 can be moved in opposite directions along the scan axis 558 during scanning of the sites 415.
As the first mask 412A is being moved in the first scan direction 558A, the first pattern beam 436A continues to illuminate a portion of the first mask 412A from initially near the right side toward the left side. At the same time, the substrate 414 is being moved in the first scan direction 558A so that the first pattern beam 436A is directed initially at the right side and continuously and subsequently toward the left side of the substrate 414.
FIG. 6B is a simplified side view of the first mask 412A, the second mask 412B, the optical assembly 420, and the substrate 414 at a beginning of an exposure of the second site 2.
At the start of exposure of the second site 2, the control system 428 (illustrated in FIG. 4) controls the illumination system 418 (illustrated in FIG. 4) to generate the slit shaped second illumination beam 435B that is directed at the second mask 412B, and controls the second mask stage assembly 422B (illustrated in FIG. 4) to position the second mask 412B so that a second mask pattern 429B is illuminated near the right side of the pattern 429B. This causes a resulting second pattern beam 436B to be directed by the optical assembly 420 at a portion of the second site 2.
Additionally, as illustrated in FIG. 6B, the second pattern beam 436B is initially directed toward a second optical inlet 421B of the optical assembly 420 along a second inlet axis 421E. The second pattern beam 436B is subsequently redirected and focused within the optical assembly 420 until the second pattern beam 436B exits the optical outlet 421C offset from the outlet axis 421F.
Further, at the beginning of the exposure of the second site 2, the control system 428 (i) controls the second mask stage assembly 422B so that the second mask 412B is being moved at a constant velocity in the first scan direction 558A along the scan axis 558, and (ii) controls the substrate stage assembly 424 (illustrated in FIG. 4) so that the substrate 414 is also being moved at a constant velocity in the first scan direction 558A. With the present design, in certain embodiments, both the second mask 412B and the substrate 414 are moved synchronously in the same scan direction 558A. Alternatively, the second mask 412B and the substrate 414 can be moved in opposite directions along the scan axis 558 during scanning of the sites 415.
It should be noted that with the design of the optical assembly 420 as illustrated herein, the exposure of the first site 1 and the second site 2 occurs with the substrate 414 being moved in the same first scan direction 558A at a substantially constant velocity. This enables greater throughput for the exposure apparatus 410 (illustrated in FIG. 4).
FIG. 6C is a simplified side view of the first mask 412A, the second mask 412B, the optical assembly 420, and the substrate 414 at a beginning of an exposure of the third site 3. It should be noted that after the exposure of the second site illustrated in FIG. 6B, the substrate 414 is stepped into the page along the Y axis.
During the exposure of the third site 3, the control system 428 (illustrated in FIG. 4) controls the illumination system 418 (illustrated in FIG. 4) to generate the slit shaped second illumination beam 435B that is directed at the second mask 412B, and controls the second mask stage assembly 422B (illustrated in FIG. 4) to position the second mask 412B so that the second mask pattern 429B is illuminated near its left side. This causes a resulting second pattern beam 436B to be directed by the optical assembly 420 at a portion of the third site 3.
Further, during the exposure of the third site 3, the control system 428 (i) controls the second mask stage assembly 422B so that the second mask 412B is being moved at a constant velocity in a second scan direction 558B (from right to left in FIG. 6C, opposite from the first scan direction 558A) along the scan axis 558 (the X axis), and (ii) controls the substrate stage assembly 424 (illustrated in FIG. 4) so that the substrate 414 is also being moved at a constant velocity in the second scan direction 558B.
FIG. 6D is a simplified side view of the first mask 412A, the second mask 412B, the optical assembly 420, and the substrate 414 at a beginning of an exposure of the fourth site 4. At the start of exposure of the fourth site 4, the control system 428 (illustrated in FIG. 4) controls the illumination system 418 (illustrated in FIG. 4) to generate the slit shaped first illumination beam 435A that is directed at the first mask 412A, and controls the first mask stage assembly 422A (illustrated in FIG. 4) to position the first mask 412A so that the first mask pattern 429A is illuminated near its left side. This causes a resulting first pattern beam 436A to be directed by the optical assembly 420 at a portion of the fourth site 4. In certain embodiments, the exposure of the fourth site 4 using reticle 412A can begin before the exposure of the third site 3 using reticle 412B has finished.
During the exposure of the fourth site 4, the control system 428 (i) controls the first mask stage assembly 422A so that the first mask 412A is being moved at a substantially constant velocity in the second scan direction 558B along the scan axis 558, and (ii) controls the substrate stage assembly 424 (illustrated in FIG. 4) so that the substrate 414 is also being moved at a substantially constant velocity in the second scan direction 558B.
It should be noted that with the design of the optical assembly 420 as illustrated herein, the exposure of the third site 3 and the fourth site 4 occur with the substrate 414 being moved in the same second scan direction 558B along the scan axis 558. Further, the four sites 1-4 can be exposed with only one stepping motion.
FIGS. 7A-7I further illustrate one embodiment of how four sites labeled 1-4 can be exposed using the exposure apparatus 410 as illustrated in FIG. 4 and as described above. In these Figures, the box with solid lines represents the first used field 762A, the box with dashed lines represents the second used field 762B, and the slashes represent the respective pattern beam. Further, in these Figures, the arrow represents the direction in which the substrate is being moved during scanning at that particular time. During the exposure of the sites 1-4, the substrate is moved down the page, then left, and then up. In FIGS. 7A-7I, it appears that the used fields 762A, 762B move, however, the substrate is actually being moved relative to the used fields 762A, 762B.
Starting with FIG. 7A, at the beginning of the exposure of the first site 1, the first pattern beam 736A (illustrated with slashes) is exposing the first site 1 and there is no second pattern beam. At this time, the first used field 762A is positioned over the first site 1, and the second used field 762B is not over any of the sites 1-4.
Next, referring to FIG. 7B, after the first site 1 is exposed, the first used field 762A is positioned over the second site 2, and the second used field 762B is positioned over the first site 1. At this time neither of the pattern beams is being generated. The amount of time in which the two beams are off is determined by the distance between the slits and the motion of the stages.
Subsequently, referring to FIG. 7C, once the second used field 762B is positioned over the second site 2, the second pattern beam 736B (illustrated with slashes) begins to expose the second site 2, and there is no first pattern beam.
Next, referring to FIG. 7D, while the second used field 762B is still positioned over the second site 2, the second pattern beam 736B (illustrated with slashes) continues to expose the second site 2, and there is no first pattern beam.
Subsequently, upon the completion of the exposure of the second site 2, the substrate is moved to the left. Referring to FIG. 7E, once the second used field 762B is positioned over the third site 3, the second pattern beam 736B (illustrated with slashes) begins to expose the third site 3, and there is no first pattern beam. At this time, the substrate is being moved up the page.
Next, referring to FIG. 7F, while the second used field 762B is still positioned over the third site 3, the second pattern beam 736B (illustrated with slashes) continues to expose the third site 3, and there is no first pattern beam.
Subsequently, referring to FIG. 7G, after the third site 3 is exposed, the first used field 762A is positioned over the third site 3, and the second used field 762B is positioned over the fourth site 4. At this time neither of the pattern beams are being generated.
Next, referring to FIG. 7H, once the first used field 762A is positioned over the fourth site 4, the first pattern beam 736A (illustrated with slashes) begins to expose the fourth site 4, and there is no second pattern beam.
Subsequently, referring to FIG. 7I, while the first used field 762A is still positioned over the fourth site 4, the first pattern beam 736A (illustrated with slashes) continues to expose the fourth site 4, and there is no second pattern beam.
In this embodiment, the system is designed so that the second site 2 is not exposed until after the exposure of the first site 1 is fully completed, and the fourth site 4 is not exposed until after the exposure of the third site 3 is fully completed. This requires an A-B-B-A exposure sequence. The benefit of this sequence is that there is never a time when both pattern beams are required, so it is easier to use a single illumination source 432A, 432B (illustrated in FIG. 4). The drawbacks of this sequence are (1) that the reticle stage acceleration must be proportional to the substrate acceleration (e.g., in a 4× reduction system, the reticle acceleration is four times the substrate acceleration), and (2) that the scanning distance is longer than that required for the sequence described below for FIGS. 8A-8I.
FIGS. 8A-8I further illustrate another embodiment of how four sites labeled 1-4 can be exposed using the exposure apparatus 410 as illustrated in FIG. 4 and as described above. Similar to the embodiment illustrated in FIGS. 7A-71, in this embodiment, the box with solid lines is the first used field 862A, the box with dashed lines is the second used field 862B, and the slashes represent the pattern beam. Further, the arrow again represents the direction in which the substrate is being moved during scanning at that particular time, with the substrate initially being moved down the page, then left, and then up during the exposure of the four sites.
Starting with FIG. 8A, at the beginning of the exposure of the first site 1, the second pattern beam 836B (illustrated with slashes) is exposing the first site 1 and there is no first pattern beam. At this time, both the first used field 862A and the second used field 862B are positioned over the first site 1. Further, at this time, the substrate is being moved down the page.
Next, referring to FIG. 8B, during continuation of exposure of the first site 1, the first used field 862A is positioned over the second site 2, and the second used field 862B is positioned over the first site 1. Once the first used field 862A is positioned over the second site 2, the first pattern beam 836A (illustrated with slashes) begins to expose the second site 2. At the same time, the second pattern beam 836B (illustrated with slashes) is still being generated and is still exposing the first site 1. Stated another way, at this time both of the pattern beams 836A, 836B are being generated, and the continuing exposure of the first site 1 coincides or overlaps with the beginning of the exposure of the second site 2.
Subsequently, referring to FIG. 8C, both the first used field 862A and the second used field 862B are positioned over the second site 2. Once the second used field 862B is positioned over the second site 2, the second pattern beam is no longer being generated, but the first pattern beam 836A (illustrated with slashes) is still being generated and is continuing exposure of the second site 2.
Next, referring to FIG. 8D, only the second used field 862B is still positioned over the second site 2, and the first used field 862A is not positioned over any of the sites. This is the condition after completion of the exposure of the second site 2. At this time, neither of the pattern beams are being generated, and the substrate is already stepping to the left.
Referring next to FIG. 8E, the second used field 862B is positioned over the third site 3, and the first used field 862A is not positioned over any of the sites. At this time, neither of the pattern beams are being generated. Further, at this time, the substrate is being moved up the page, and is finishing its stepping motion to the left.
Next, referring to FIG. 8F, once the first used field 862A is positioned over the third site 3, the first pattern beam 836A (illustrated with slashes) begins to expose the third site 3. At this time, the second used field 862B is still positioned over the third site 3, and no second pattern beam is being generated.
Subsequently, referring to FIG. 8G, during continuation of exposure of the third site 3, the first used field 862A is still positioned over the third site 3, and the second used field 862B is now positioned over the fourth site 4. Once the second used field 862B is positioned over the fourth site 4, the second pattern beam 836B (illustrated with slashes) begins to expose the fourth site 4. At the same time, the first pattern beam 836A (illustrated with slashes) is still being generated and is still exposing the third site 3. Stated another way, at this time both of the pattern beams 836A, 836B are being generated, and the continuing exposure of the third site 3 coincides or overlaps with the beginning of the exposure of the fourth site 4.
Next, referring to FIG. 8H, both the first used field 862A and the second used field 862B are now positioned over the fourth site 4. Once the first used field 862A is positioned over the fourth site 4, the first pattern beam is no longer being generated, but the second pattern beam 836B (illustrated with slashes) is still being generated and is continuing exposure of the fourth site 4.
Subsequently, referring to FIG. 81, only the first used field 862A is still positioned over the fourth site 4, and the second used field 862B is not positioned over any of the sites. At this time, neither of the pattern beams are being generated.
In this embodiment, the system is designed so that the exposure of the second site 2 is started prior to the exposure of the first site 1 being fully completed.
Comparing the exposures illustrated in FIGS. 7A-7I with exposures illustrated in FIGS. 8A-8I, the overall scanning distance is longer for the embodiment illustrated in FIGS. 7A-7I. Therefore, the exposure of FIG. 8A-8I is completed faster, leading to higher overall throughput, assuming the same scan velocity for the two cases. The B-A-A-B sequence shown in FIGS. 8A-8I achieves this higher throughput by having time when both pattern beams are used simultaneously. The drawbacks of this sequence are (1) that the reticle stage acceleration must be proportional to the substrate acceleration (e.g., in a 4× reduction system, the reticle acceleration is four times the substrate acceleration), and (2) the design of the illumination system may be more difficult compared to what is required for the sequence shown in FIGS. 7A-7I.
FIGS. 9A-9I further illustrate another embodiment of how four sites labeled 1-4 can be exposed using the exposure apparatus 410 as illustrated in FIG. 4 and as described above. Similar to the embodiment illustrated in FIGS. 7A-7I and 8A-8I, in this embodiment, the box with solid lines is the first used field 962A, the box with dashed lines is the second used field 962B, and the slashes represent the pattern beam. Further, the arrow again represents the direction in which the substrate is being moved during scanning at that particular time, with the substrate initially being moved down the page, then left, and then up during the exposure of the four sites.
Starting with FIG. 9A, at the beginning of the exposure of the first site 1, the first pattern beam 936A (illustrated with slashes) is exposing the first site 1 and there is no second pattern beam. At this time, the first used field 962A is positioned over the first site 1, and the second used field 962B is not over any of the sites 1-4.
Next, referring to FIG. 9B, after the first site 1 is exposed, the first used field 962A is positioned over the second site 2, and the second used field 962B is positioned over the first site 1. At this time neither of the pattern beams is being generated.
Subsequently, referring to FIG. 9C, once the second used field 962B is positioned over the second site 2, the second pattern beam 936B (illustrated with slashes) begins to expose the second site 2, and there is no first pattern beam.
Next, referring to FIG. 9D, while the second used field 962B is still positioned over the second site 2, the second pattern beam 936B (illustrated with slashes) continues to expose the second site 2, and there is no first pattern beam.
Subsequently, upon the completion of the exposure of the second site 2, the substrate is moved to the left. Referring to FIG. 9E, once the second used field 962B is positioned over the third site 3, neither of the pattern beams is being generated.
Next, referring to FIG. 9F, once the first used field 962A is positioned over the third site 3, the first pattern beam 736A (illustrated with slashes) begins to expose the third site 3, and there is no second pattern beam.
Subsequently, referring to FIG. 9G, while still exposing the third site 3, the first used field 962A is positioned over the third site 3, and the second used field 962B is positioned over the fourth site 4. At this time both pattern beams 936A, 936B are being generated.
Next, referring to FIG. 9H, with the second used field 962B is still positioned over the fourth site 4, the second pattern beam 936B (illustrated with slashes) continues to expose the fourth site 4, and there is no first pattern beam.
Subsequently, referring to FIG. 9I, after the second used field 962B is no longer positioned over the fourth site 4, and there is no pattern beam being generated.
With this sequence, the first site 1 and the third site 3 are exposed with the first pattern beam 936A, and the second site 2 and the fourth site 4 are exposed with the second pattern beam 936B. This sequence provides the same throughput and scanning distance as the sequence illustrated in FIGS. 7A-7I, and requires some times (half as much) when both pattern beams are used simultaneously, like the sequence in FIGS. 8A-8I. The advantage of this sequence is that the two masks are always used for alternate exposures, so the requirement for mask acceleration is much lower. In other words, each of the mask stages 422A, 422B can perform its “turn-around” acceleration during an exposure using the other mask, 412B, 412A, respectively. For future machines with very high throughput, this advantage may make this sequence the preferred embodiment.
It should be noted that with these designs, greater throughput of the exposure apparatus is achieved because the number of steps required to process the substrate is less than if the sites are scanned along the long dimension of the sites.
FIGS. 10A-10D further illustrate one embodiment of how a first site 1 can be exposed using the exposure apparatus 410 as illustrated in FIG. 4 and as described above. Similar to the embodiments illustrated above, in this embodiment, the box with solid lines represents the first used field 1062A, the box with dashed lines represents the second used field 1062B, and the slashes represent the pattern beam. Further, the arrow again represents the direction in which the substrate is being moved during scanning at that particular time, with the substrate initially being moved down the page, and then up during the exposure of the first site 1. Moreover, in this embodiment, the first site 1 is sequentially exposed to the first pattern beam 1036A and the second pattern beam 1036B.
Starting with FIG. 10A, at the beginning of the exposure of the first site 1, the first pattern beam 1036A (illustrated with slashes) is exposing the first site 1 and there is no second pattern beam. At this time, the first used field 1062A is positioned over the first site 1, and the second used field 1062B is not positioned over any of the sites. Further, at this time, the substrate is being moved down the page.
Next, referring to FIG. 10B, the first used field 1062A is now positioned over a second site 2 (i.e., not over the first site 1) and the second used field 1062B is now positioned over the first site 1, and the substrate is still being moved down the page. At this time, neither of the pattern beams are being generated.
Subsequently, referring to FIG. 10C, the first used field 1062A is again positioned over the second site 2 (i.e., not over the first site 1) and the second used field 1062B is positioned over the uppermost portion of the first site 1. At this time, the substrate is beginning to be moved back up the page. With the second used field 1062B being positioned over the uppermost portion of the second site 2, and the substrate being moved up the page, the second pattern beam 1036B is being generated and the first site 1 is being exposed. Further, at this time, no first pattern beam is being generated.
Next, referring to FIG. 10D, the first used field 1062A is positioned over the first site 1, and the second used field 1062B is not positioned over any of the sites. At this time, neither of the pattern beams are being generated.
Other sequences can be utilized than that illustrated in FIGS. 10A-10D. For example, two adjacent sites can be sequentially scanned in one motion, then the substrate can be turned around and the second exposure of these sites can be performed. For example, while moving substrate in one direction along the X axis, the first site can be exposed using the first reticle and subsequently the second site can be exposed using second reticle (similar as illustrated in FIGS. 9A-9D). Next, the direction of the substrate along the X axis can be reversed, the second site can exposed using the first reticle, and subsequently the first site can be exposed using the second reticle. This is similar to sequence illustrated in FIG. 9A-9I, except without the Y direction stepping motion.
FIGS. 11A-11D further illustrate another embodiment of how a first site 1 can be exposed using the exposure apparatus 410 as illustrated in FIG. 4 and as described above. Similar to the embodiments illustrated above, in this embodiment, the box with solid lines is the first used field 1162A, the box with dashed lines is the second used field 1162B, and the slashes represent the pattern beam. Further, the arrow again represents the direction in which the substrate is being moved during scanning at that particular time, with the substrate being moved down the page during the exposure of the first site 1. Moreover, in this embodiment, the first site 1 is exposed to both the first pattern beam 1136A and the second pattern beam 1136B.
Starting with FIG. 11A, at the beginning of the exposure of the first site 1, the first pattern beam 1136A (illustrated with slashes) is exposing the first site 1 and there is no second pattern beam. At this time, the first used field 1162A is positioned over the first site 1, and the second used field 1162B is not positioned over any of the sites 1-4.
Next, referring to FIG. 11B, both the first used field 1162A and the second used field 1162B are now positioned over the first site 1. At this time, both of the pattern beams 1136A, 1136B (illustrated with slashes) are being generated, and the first site 1 is simultaneously being exposed to both the first pattern beam 1136A and the second pattern beam 1136B.
Subsequently, referring to FIG. 11C, the first used field 1162A is now positioned over the second site 2 (i.e., not over the first site 1) and the second used field 1162B is still positioned over the first site 1. At this time, the second pattern beam 1136B (illustrated with slashes) is exposing the first site 1 and no first pattern beam 1136A is being generated.
Next, referring to FIG. 11D, both the first used field 1162A and the second used field 1162B are positioned over the second site 2 (i.e., not over the first site 1). At this time, neither of the pattern beams are being generated.
FIG. 12 is a schematic illustration of the first mask 412A, the second mask 412B, the substrate 414, and one, non-exclusive embodiment of an optical assembly 1220 having features of the present invention. As noted above, the optical assembly 1220 projects and/or focuses the first pattern beam 436A and the second pattern beam 436B onto the substrate 414.
As illustrated, the optical assembly 1220 includes (i) the first optical inlet 421A, (ii) the second optical inlet 421B, (iii) the optical outlet 421C, (iv) a plurality of first vertical optical elements 1220AA that are positioned along the first inlet axis, (v) a plurality of second vertical optical elements 1220AB that are positioned along the second inlet axis, (vi) a plurality of first transverse optical elements 1220AC that are positioned along a first transverse axis between the first inlet axis and the outlet axis, (vii) a plurality of second transverse optical elements 1220AD that are positioned along a second transverse axis between the second inlet axis and the outlet axis, and (viii) a plurality of third vertical optical elements 1220AE that are positioned along the outlet axis.
During projection and/or focusing of the first pattern beam 436A from the first mask 412A onto the substrate 414, the first pattern beam 436A is initially directed through the first optical inlet 421A and through the plurality of first vertical optical elements 1220AA. Subsequently, the first pattern beam 436A is redirected toward the plurality of first transverse optical elements 1220AC. Next, the first pattern beam 436A is redirected toward the plurality of third vertical optical elements 1220AE. The third vertical optical elements 1220AE then project and/or focus the first pattern beam 436A through the optical outlet 421C and toward the substrate 421 offset from the outlet axis.
Similarly, during projection and/or focusing of the second pattern beam 436B from the second mask 412B onto the substrate 414, the second pattern beam 436B is initially directed through the second optical inlet 421B and toward the plurality of second vertical optical elements 1220AB. Subsequently, the second pattern beam 436B is redirected toward the plurality of second transverse optical elements 1220AD. Next, the second pattern beam 436B is redirected toward the plurality of third vertical optical elements 1220AE. The third vertical optical elements 1220AE then project and/or focus the second pattern beam 436B through the optical outlet 421C and toward the substrate 414 offset from the outlet axis.
As illustrated in FIG. 12, the first vertical optical elements 1220AA are substantially identical to the second vertical optical elements 1220AB. Additionally, the first transverse optical elements 1220AC are substantially identical to the second transverse optical elements 1220AD. Accordingly, only the first vertical optical elements 1220AA and the first transverse optical elements 1220AC will be described in detail herein. Further, both beams 436A, 436B travel through the same third vertical optical elements 1220AE.
The first vertical optical elements 1220AA include a plurality of individual optical elements labeled E1 through E18. In this embodiment, the first pattern beam 436A is altered and/or focused as it initially passes in a generally downward direction through optical elements E1 through E13. Optical elements E1 through E13 are optical lenses that can be made from material such as silicon dioxide (SiO₂). Subsequently, the first pattern beam 436A is reflected off optical element E14 so that it is now directed in a generally upward direction. In one embodiment, optical element E14 can be a spherical mirror. Next, the first pattern beam 436A is directed through optical elements E15 through E17. As illustrated in FIG. 10, optical elements E15 through E17 are the same as optical elements E11 through E13, with the first pattern beam 436A passing through optical elements E11 through E13 in one direction and subsequently passing through optical elements E15 through E17 and in the substantially opposite direction. Next, the first pattern beam 436A is reflected transversely off optical element E18 so that it is now redirected toward the first transverse optical elements 1220AC. Optical element E18 can be a mirror or other reflecting element.
The first transverse optical elements 1220AC include a plurality of individual optical elements E19 through E29. The first pattern beam 436A is altered and/or refocused as it passes in a generally transverse or horizontal direction through optical elements E19 through E28. Optical elements E19 through E28 are optical lenses that can be made from material such as silicon dioxide (SiO₂). Subsequently, the first pattern beam 436A is reflected off optical element E29 so that it is now redirected toward the third vertical optical elements 1120AE. In one embodiment, optical element E29 can be a field splitting V-mirror.
The third vertical optical elements 1220AE include a plurality of optical elements E30 through E45. The first pattern beam 436A is altered and/or refocused as it passes in a generally downward direction through optical elements E30 through E45. Optical elements E30 through E45 are optical lenses that can be made from material such as silicon dioxide (SiO₂). The first pattern beam 436A then passes through element E46 (represented as X's), which is a fluid, such as water, if the exposure apparatus 410 is an immersion type system, before being projected and/or focused onto the substrate 414.
It should be noted that the design of the optical assembly 1220 illustrated in FIG. 12 contains more intermediate images than the optical assemblies used in prior art lithography machines. It should be noted that these intermediate images can be highly aberrated, as is the case in this embodiment. This makes it easier to increase the field size without increasing the diameter of the optical elements, since the optical distance between the reticle and the wafer is much longer than in the current state of the art for projection optical assemblies, thanks to the folded optical path (i.e. the physical distance between the plane containing the reticle 412A and the plane containing the substrate 414 is nominally the same as current state of the art). Further, the optical assembly 1220 allows for the continuous exposure of two or more shots per scanning motion. With this exposure pattern, the reduction in scanning time is much greater than the increase in stepping time, and dramatic improvements in throughput are possible.
Table 1, as provided below, illustrates one, non-exclusive example of a prescription for the optic elements E1 through E46 of the optical assembly 1216 illustrated in FIG. 12. More particularly, for each optical element E1 through E46, the charts in Table 1 show a prescription for (i) the radius of curvature for the front of the optical element, (ii) the radius of curvature for the back of the optical element, (iii) the thickness of the optical element (in the column for thickness the top number represents the distance between that optical element and the preceding optical element (or the mask in the case of optical element E1), and the bottom number represents the actual thickness of that optical element, (iv) the aperture diameter for the front of the optical element, and (v) the aperture diameter for the back of the optical element. The thickness of each optical element is specified along the optical axis (e.g. the center of rotation for the element).

TABLE 1

		APERTURE
ELEMENT	RADIUS OF CURVATURE	DIAMETER

NUMBER	FRONT	BACK	THICKNESS	FRONT	BACK

MASK

INF

80.0000

E1	332.3631	CX	−772.3579	CX	38.0763	215.2012	217.2506
					26.9220
E2	1988.1790	CX	−557.1967	CX	26.6978	220.9056	221.1825
					56.1372

E3	128.4263	CX	A(1)	31.0843	198.8483	187.8534
				26.0025

E4	98.6558	CX	321.1966	CC	45.2849	159.9568	143.6474
					16.3918
E5	−454.4909	CC	−730.0124	CX	59.99325	137.4985	118.9757
					59.7289
E6	−64.8711	CC	−199.1701	CX	12.5000	125.5907	190.0548
					1.0877
E7	−224.3732	CC	−132.7050	CX	46.3257	196.0660	217.1116
					1.0000

E8	A(2)	−158.7960	CX	45.6873	245.0434	260.0687
				1.0000

E9	−646.1248	CC	−226.2058	CX	51.0836	289.0873	295.5915
					1.0000

E10	360.6986	CX	A(3)	53.3734	287.2861	282.7083
				139.9997

		211.4006
	100.0000

E11	237.9744	CX	−1445.3266	CX	51.2169	244.1453	240.7614
					174.1733

E12	A(4)	487.4478	CC	12.5000	158.1046	166.9962
				58.1229

E13	−98.2161	CC	−210.5104	CX	12.5000	168.7470	212.4076
					24.2148

E14

−145.6557 CC

−24.2148

218.4194

E15	−210.5104	CX	−98.2161	CC	−12.5000	209.9116	168.2949
					−58.1229

E16	487.4478	CC	A(5)	−12.5000	166.3525	155.5700
				−174.1733

E17	−1445.3266	CX	237.9744	CX	−51.2169	252.3990	255.2359
					−100.0000

DECENTER(1)

E18	INF	0.0000	358.2570
			230.1752
		139.9999

E19	A(6)	−489.7915	CX	48.1053	269.5593	273.1352
				1.0509

E20	440.2750	CX	−1319.4966	CX	42.3662	278.5086	276.5223
					1.0004

E21	153.2021	CX	A(7)	35.3619	249.4052	236.0525
				1.0048

E22	129.8182	CX	247.8748	CC	51.0939	218.2553	199.2937
					14.1804
E23	139.9820	CX	69.7240	CC	17.4815	161.4679	118.1128
					56.7295
E24	−317.8201	CC	−19220.6836	CX	12.5000	92.5138	103.8677
					51.6277
E25	−239.6328	CC	−120.1306	CX	53.8056	186.4776	208.1471
					1.0000

E26	A(8)	−134.3606	CX	57.5209	232.5554	249.2932
				3.2068

E27	3402.1195	CX	−375.2978	CX	40.6273	270.0570	271.5381
					9.9100
E28	501.3345	CX	−4078.3847	CX	31.4270	258.1145	253.6591
					140.0003

DECENTER(2)

E29	INF	0.0000	340.0505
			167.4372
		−119.0000

E30	−725.7800	CX	971.2181	CX	−26.7346	215.7113	218.7057
					−1.0000
E31	−246.2088	CX	−2291.7420	CC	−37.5566	227.3402	224.6272
					−1.0000
E32	−240.3807	CX	−491.2120	CC	−27.0952	217.7132	211.0205
					−1.0000

E33	−359.5177	CX	A(9)	−26.0330	208.1157	200.6343
				−2.5888

E34	3436.6049	CC	−155.1981	CC	−12.5000	201.2703	181.4202
					−53.9084

E35	201.2753	CC	A(10)	−12.5000	181.5783	206.3011
				−32.1960

E36	A(11)	22055.3033	CX	−18.2557	222.3822	232.1830
				−5.7398

E37	−444.9630	CX	855.8885	CX	−44.4071	269.0140	274.6713
					−1.0250

E38	−1241.2380	CX	A(12)	−48.8825	285.3656	288.3814
				4.0469
E39	505.0198	CC	A(13)	−19.5442	288.9709	293.2339
				−27.7418

E40	A(14)	300.9422	CX	−54.8835	293.3251	329.7481
				−1.0029

E41	−384.4074	CX	1165.4799	CX	−69.9286	356.7095	354.3822
					−1.0000

		347.3775
	−1.0000

APERTURE STOP

313.1895

E42	−192.8071	CX	−336.3459	CC	−57.1654	313.1895	301.4309
					−1.0015

E43	−146.6712	CX	A(15)	−63.7532	260.7714	240.3029
				−1.2011
E44	−93.7790	CX	A(16)	−53.0084	174.6861	139.7743
				−1.0108
E45	−64.9508	CX	INF	−44.5062	105.4047	44.5875

E46

INF

−1.5000

44.5875

36.2567

SUBSTRATE	INF		36.2567

In Table 1, it should be noted that (i) positive radius indicates the center of curvature is to the right; (ii) negative radius indicates the center of curvature is to the left; (iii) dimensions are given in millimeters; (iv) thickness is axial distance to next surface; and (v) image diameter is a paraxial value, it is not a ray traced value.
Table 2, as provided below, illustrates the calculation of aspheric constants related to the radius of curvature for certain of the optical elements as shown in Table 1. More particularly, aspheric constant A(1) relates to the radius of curvature for the back of optical element E3; aspheric constant A(2) relates to the radius of curvature for the front of optical element E8; aspheric constant A(3) relates to the radius of curvature for the back of optical element E10; aspheric constant A(4) relates to the radius of curvature for the front of optical element E12; aspheric constant A(5) relates to the radius of curvature for the back of optical element E16; aspheric constant A(6) relates to the radius of curvature for the front of optical element E19; aspheric constant A(7) relates to the radius of curvature for the back of optical element E21; aspheric constant A(8) relates to the radius of curvature for the front of optical element E26; aspheric constant A(9) relates to the radius of curvature for the back of optical element E33; aspheric constant A(10) relates to the radius of curvature for the back of optical element E35; aspheric constant A(11) relates to the radius of curvature for the front of optical element E36; aspheric constant A(12) relates to the radius of curvature for the back of optical element E38; aspheric constant A(13) relates to the radius of curvature for the back of optical element E39; aspheric constant A(14) relates to the radius of curvature for the front of optical element E40; aspheric constant A(15) relates to the radius of curvature for the back of optical element E43; and aspheric constant A(16) relates to the radius of curvature for the back of optical element E44.
Additionally, within the formula for the aspheric constants, Y represents the distance from the optical axis (i.e., the first inlet axis, a first transverse axis, or the outlet axis), CURV represents (1/radius of curvature), and K represents the conic constant.

TABLE 2

ASPHERIC CONSTANTS
$Z = \frac{(CURV) Y^{2}}{1 + {(1 - (1 + K) {(CURV)}^{2} Y^{2})}^{1 / 2}} + (A) Y^{4} + (B) Y^{6} + (C) Y^{8} + (D) Y^{10} + (E) Y^{12} + (F) Y^{14} + (G) Y^{16} + (H) Y^{18} + (J) Y^{20}$

		K	A	B	C	D
ASPHERIC	CURV	E	F	G	H	J

A(1)	0.00521230	0.000000	7.36515E−08	5.65704E−12	−1.19986E−15	3.47493E−20
		1.94010E−24	−2.67446E−28	0.00000E+00	0.00000E+00	0.00000E+00
A(2)	−0.00474024	0.000000	1.94442E−08	7.19217E−13	−4.39422E−17	−8.49737E−22
		1.08518E−25	−2.62326E−30	0.00000E+00	0.00000E+00	0.00000E+00
A(3)	−0.00181913	0.000000	1.97669E−08	−2.81921E−14	−2.03611E−18	3.92721E−23
		8.64464E−29	−2.01755E−32	0.00000E+00	0.00000E+00	0.00000E+00
A(4)	−0.00943927	0.000000	4.03091E−07	−1.84915E−11	−3.06102E−16	−5.60022E−20
		9.77410E−24	−1.64771E−27	0.00000E+00	0.00000E+00	0.00000E+00
A(5)	−0.00943927	0.000000	1.22035E−07	1.75899E−12	−8.89537E−18	2.56518E−20
		−1.72833E−24	2.12380E−28	0.00000E+00	0.00000E+00	0.00000E+00
A(6)	0.00250445	0.000000	−2.24797E−08	−1.71809E−14	4.18962E−18	−1.25992E−22
		1.93598E−27	−1.52571E−32	0.00000E+00	0.00000E+00	0.00000E+00
A(7)	0.00598617	0.000000	−1.78129E−08	−1.34754E−12	−9.63168E−18	−5.96286E−22
		8.22593E−26	−3.07075E−30	0.00000E+00	0.00000E+00	0.00000E+00
A(8)	−0.00402385	0.000000	−5.66102E−08	4.94563E−13	−2.86196E−17	−1.14660E−21
		6.70516E−26	−1.34290E−30	0.00000E+00	0.00000E+00	0.00000E+00
A(9)	0.00043217	0.000000	−4.01551E−08	7.98475E−13	−8.77129E−17	−1.03388E−21
		5.28663E−25	−4.41691E−29	6.99988E−34	0.00000E+00	0.00000E+00
A(10)	−0.00708334	0.000000	1.59565E−07	−5.12216E−12	3.09234E−16	−1.36558E−20
		6.81623E−25	−9.67188E−30	−7.26516E−35	0.00000E+00	0.00000E+00
A(11)	−0.00159664	0.000000	8.79056E−08	−4.58660E−12	1.44100E−16	−1.79547E−20
		4.80695E−25	−2.72623E−29	1.93370E−33	0.00000E+00	0.00000E+00
A(12)	0.00262213	0.000000	1.87932E−08	7.71419E−13	−1.47309E−16	3.46140E−21
		1.30616E−25	−1.07939E−29	1.84542E−34	0.00000E+00	0.00000E+00
A(13)	0.00317050	0.000000	−2.49489E−08	−8.47598E−13	1.17616E−16	−3.41773E−21
		−1.01449E−25	8.58972E−30	−1.27042E−34	0.00000E+00	0.00000E+00
A(14)	0.00395847	0.000000	6.54729E−09	3.01118E−13	1.06282E−17	−1.83601E−21
		1.35202E−25	−5.49884E−30	9.45241E−35	0.00000E+00	0.00000E+00
A(15)	−0.00373059	0.000000	2.81186E−08	−3.40496E−12	1.73002E−16	−4.39804E−21
		−1.60826E−25	1.48359E−29	−3.52669E−34	0.00000E+00	0.00000E+00
A(16)	−0.00548781	0.000000	−1.89752E−07	−2.61284E−13	−1.75568E−15	2.78432E−20
		2.85207E−23	−8.14237E−27	5.98295E−31	0.00000E+00	0.00000E+00

Table 3, as provided below, illustrates the decentering information as it relates to optical elements E18 and E29 (i.e., certain of the mirror elements). Table 3 further provides additional system characteristics for the optical assembly 1120.

TABLE 3

DECENTERING CONSTANTS

DECENTER	X	Y	Z	ALPHA	BETA	GAMMA

D (1)	0.0000	0.0000	0.0000	−45.0000	0.0000	0.0000	(BEND)
D (2)	0.0000	0.0000	0.0000	−45.0000	0.0000	0.0000	(BEND)

A decenter defines a new coordinate system (displaced and/or rotated) in

which subsequent surfaces are defined. Surfaces following a decenter are

aligned on the local mechanical axis (z-axis) of the new coordinate system.

The new mechanical axis remains in use until changed by another decenter.

The order in which displacements and tilts are applied on a given surface is

specified using different decenter types and these generate different new

coordinate systems; those used here are explained below. Alpha, beta, and

gamma are in degrees.

DECENTERING CONSTANT KEY:

TYPE	TRAILING CODE	ORDER OF APPLICATION

DECENTER		DISPLACE (X, Y, Z)
		TILT (ALPHA, BETA, GAMMA)
		REFRACT AT SURFACE
		THICKNESS TO NEXT SURFACE
DECENTER & BEND	BEND	DECENTER
		(X, Y, Z, ALPHA, BETA, GAMMA)
		REFLECT AT SURFACE
		BEND (ALPHA, BETA, GAMMA)
		THICKNESS TO NEXT SURFACE

REFERENCE WAVELENGTH = 193.3 NM

SPECTRAL REGION = 193.3-193.3 NM

This is non-symmetric system. If elements with power are decentered

or tilted, the first order properties are probably inadequate in describing

the system characteristics.

	INFINITE CONJUGATES
	EFL =	8645.9595
	BFL =	2159.9899
	FFL =	23989.7701
	F/NO =	0.0000
	AT USED CONJUGATES
	REDUCTION =	−0.2500
	FINITE F/NO =	−0.3704
	OBJECT DIST =	80.0000
	TOTAL TRACK =	763.7529
	IMAGE DIST =	−1.5000
	OAL =	685.2529
	PARAXIAL
	IMAGE HT =	18.1250
	IMAGE DIST =	−1.5000
	SEMI-FIELD
	ANGLE =	0.0000
	ENTR PUPIL
	DIAMETER =	0.717E+10
	DISTANCE =	0.100E+11
	EXIT PUPIL
	DIAMETER =	4314.9615
	DISTANCE =	2159.9951

NOTES

FFL is measured from the first surface

BFL is measured from the last surface

It should be noted that the projection optical assembly 1216 provided herein is uniquely designed so that a plurality of intermediate images are directed at the field splitting V-mirror E-29 inside the projection optical assembly 1216. Stated in another fashion, with the present design, the field splitting V-mirror E-29 is positioned away from the image plane of the optical assembly 1216. As used herein, the term “image plane” shall mean the plane in which an image produced by the optical assembly is formed. With the present design, the image plane of the optical assembly 1216 is located at the substrate. Thus, in FIG. 12, elements E-30 through E-46 separate the field splitting V-mirror E-29 from the image plane. With the present design, many aberrated images are transmitted through elements E-30-E-46. The aberrated images give the optical designer much more flexibility in balancing aberrations before and after the V-mirror E-29. This also enables the larger field size for scanning along the short dimension of the site (X axis scan), without a larger and more complicated optical design.
Additionally, in the embodiment illustrated in FIG. 12, the projection optical assembly 1216 is a Catadioptric design that includes one or more lenses and one or more curved mirrors. In this embodiment, the projection optical assembly 1216 includes at least one concave mirror (e.g. E14 for each optical path), for the purposes of field curvature correction over the large field size of 33 mm. It is conceivable that the projection optical assembly 1216 can be designed with more than one curved mirror per optical path.
Further with the projection optical assembly 1216 provided herein, the fold mirror E18 allows light to be incident on, and reflected from, the concave mirror E14 without obscuration. The fold direction is in the short direction of the field (e.g. 5 mm at the wafer), and it is close to a second intermediate image (FIG. 12 illustrates the rays coming to a focus right next to E18, as they do next to E29). This facilitates the folding arrangement at E18, in the same way that it does at the V-mirror E29.
Additionally, it should be noted that the projection optical assembly 1216 illustrated and described herein is a 4× reduction system that reduces the size of the projected image between elements E1 and E45. Alternatively, the projection optical assembly 1216 can be designed to be a 1× system, a magnification system, or a reduction system that is greater than or less than 4×.
FIG. 13 is a simplified perspective view that includes, a first mask 1312A, a second mask 1312B, a third mask 1312C, a fourth mask 1312D, and another embodiment of an optical assembly 1320. In this embodiment, the optical assembly 1320 projects and/or focuses a first pattern beam 1336A from the first mask 1312A, a second pattern beam 1336B from the second mask 1312B, a third pattern beam 1336C from the third mask 1312C, and a fourth pattern beam 1336D from the fourth mask 1312D onto the substrate 1414 (illustrated in FIG. 14).
In this embodiment, the masks 1312A-1312D can be individually positioned and individually illuminated, and the substrate can be positioned with components that somewhat similar to those described above and illustrated in FIG. 4. As provided herein, the mask patterns from the four masks 1312A-1312D can be sequentially transferred to the substrate 414 while the substrate 14 is being moved along the X axis (e.g. the scanning along the short dimension of the site) to provide further improvements in the throughput of the system.
One embodiment of a four mask exposure apparatus is disclosed in concurrently filed application Ser. No. ______, entitled “Optical Imaging System and Method for Imaging Up to Four Reticles to a Single Imaging Location” (PAO1041-00/045004/Oremland Ref. No. 6162.118US), which is assigned to the assignee of the present invention, and is incorporated by reference herein.
The design of the optical assembly 1320 can be varied depending on the requirements of the exposure apparatus. As illustrated, the optical assembly 1320 is substantially similar to the optical assembly 1220 illustrated in FIG. 12. For example, the design, positioning and orientation of optical elements E6 through E46 (the immersion fluid is not shown in FIG. 13) is substantially repeated in this embodiment. Accordingly, a detailed description that portion of the optical assembly 1320 will not be repeated herein. However, the optical assembly 1320, as illustrated in the embodiment shown in FIG. 13, includes (i) optical elements E1 through E5, which are positioned substantially between the first mask 1312A and optical element E6 and are oriented substantially transversely relative to optical element E6, (ii) optical elements E1′ through E5′, which are positioned substantially between the second mask 1312B and optical element E6 and are oriented substantially transversely relative to optical element E6, (iii) optical elements E1″ through E5″, which are positioned substantially between the third mask 1312C and optical element E6″ and are oriented substantially transversely relative to optical element E6″, and (iv) optical elements E1′″ through E5′″, which are positioned substantially between the fourth mask 1312D and optical element E6″ and are oriented substantially transversely relative to optical element E6″.
Additionally, the optical assembly 1320 further includes a first switching mirror 1384A that is positioned substantially between optical elements E5 and E6 and between optical elements E5′ and E6, and a second switching mirror 1384B that is positioned substantially between optical elements E5″ and E6″ and between optical elements E5′″ and E6″ on the opposite side of the optical assembly 1320. The first switching mirror 1384A enables the optical assembly 1320 to selectively, alternatively and/or sequentially project and/or focus the first pattern beam 1336A from the first mask 1312A onto the substrate 414, and the second pattern beam 1336B from the second mask 1312B onto the substrate 414. Similarly, the second switching mirror 1384B enables the optical assembly 1320 to selectively, alternatively and/or sequentially project and/or focus the third pattern beam 1336C from the third mask 1312C onto the substrate 414, and the fourth pattern beam 1336D from the fourth mask 1312D onto the substrate 414.
The process of the optical assembly 1320 projecting and/or focusing the first pattern beam 1336A from the first mask 1312A onto the substrate 414 is substantially similar to the projecting and/or focusing of the second pattern beam 1336B from the second mask 1312B, the third pattern beam 1336C from the third mask 1312C, and/or the fourth pattern beam 1336D from the fourth mask 1312D onto the substrate 414.
FIG. 14 is a simplified top view of one non-exclusive embodiment of a substrate 1414 that was exposed utilizing the four mask design and the optical assembly 1320 illustrated in FIG. 13. The design of the substrate 1414 is similar to the substrate 414 described above and illustrated in FIG. 5A. However, in FIG. 14, the sequence in which the sites 1415 are exposed is different.
In this embodiment, the substrate 1414 is again labeled “1” through “32” (one through thirty-two). In this example, the labels “1” through “32” represent one non-exclusive embodiment of the sequence in which mask patterns from each of the first mask 1312A, the second mask 1312B, the third mask 1312C and the fourth mask 1312D (illustrated In FIG. 13) can be transferred to the sites 1415 on the substrate 1414.
Moreover, FIG. 14 includes an exposure pattern 1452A (illustrated with a dashed line) which further illustrates the order in which the mask patterns are transferred to sites 1415. In this example, the exposure pattern 1452A comprises a plurality of scanning operations 1452B and a plurality of stepping operations 1452C, wherein the scanning operations 1452B and the stepping operations 1452C alternate so that the exposure proceeds in a scan-step-scan-step-scan fashion. In this embodiment, the scanning 1452B occurs as the substrate 1414 is moved along a scan axis 1458 (the X axis), and the stepping 1452C occurs as the substrate 1414 is moved along a step axis 1460 (the Y axis).
It should be noted that in this embodiment, the sites are scanned along the short dimension of the sites. This allows for greater throughput of the exposure apparatus because there are fewer steps of the substrate 1414 required during the exposure of the substrate 1414.
In this embodiment, because four individual masks 1312A, 1312B, 1312C, 1312D are utilized, four adjacent sites 1415 (e.g. 1, 2, 3 and 4) can be scanned sequentially while moving the substrate 1414 at a constant velocity along the scan axis 1458. As a result thereof, the substrate 1414 does not have to be stepped and reversed in direction between the exposures of adjacent sites 1415. Instead, for the embodiment illustrated in FIG. 13, the substrate 1414 is only stepped between the exposure of sets of four adjacent sites 1415 aligned on the scan axis 1458. Stated in another fashion, with the present design, there is one stepping motion for every four sites 1415 scanned. This results in fewer steps and significantly improved throughput from the exposure apparatus 410 (illustrated in FIG. 4).
It should be noted that in this example, the site 1415 that is exposed first and the order in which the sites 1415 are exposed can be different than that illustrated in FIG. 14. Further, the site 1415 that is first exposed can be located away from the edge of the substrate 1414.
Semiconductor devices can be fabricated using the above described systems, by the process shown generally in FIG. 15A. In step 1501 the device's function and performance characteristics are designed. Next, in step 1502, a mask (reticle) having a pattern is designed according to the previous designing step, and in a parallel step 1503 a wafer is made from a silicon material. The mask pattern designed in step 1502 is exposed onto the wafer from step 1503 in step 1504 by a photolithography system described hereinabove in accordance with the present invention. In step 1505, the semiconductor device is assembled (including the dicing process, bonding process and packaging process), finally, the device is then inspected in step 1506.
FIG. 15B illustrates a detailed flowchart example of the above-mentioned step 1504 in the case of fabricating semiconductor devices. In FIG. 15B, in step 1511 (oxidation step), the wafer surface is oxidized. In step 1512 (CVD step), an insulation film is formed on the wafer surface. In step 1513 (electrode formation step), electrodes are formed on the wafer by vapor deposition. In step 1514 (ion implantation step), ions are implanted in the wafer. The above mentioned steps 1511-1514 form the preprocessing steps for wafers during wafer processing, and selection is made at each step according to processing requirements.
At each stage of wafer processing, when the above-mentioned preprocessing steps have been completed, the following post-processing steps are implemented. During post-processing, first, in step 1515 (photoresist formation step), photoresist is applied to a wafer. Next, in step 1516 (exposure step), the above-mentioned exposure device is used to transfer the circuit pattern of a mask (reticle) to a wafer. Then in step 1517 (developing step), the exposed wafer is developed, and in step 1518 (etching step), parts other than residual photoresist (exposed material surface) are removed by etching. In step 1518 (photoresist removal step), unnecessary photoresist remaining after etching is removed. Multiple circuit patterns are formed by repetition of these preprocessing and post-processing steps.
It is to be understood that the exposure apparatuses 10 disclosed herein are merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.

Claims

1. An exposure apparatus for transferring a first mask pattern to a substrate, the substrate including a first site having a first site dimension along a first axis and a second site dimension along a second axis that is perpendicular to the first axis, wherein the second site dimension is larger than the first site dimension, the exposure apparatus comprising:

an illumination system that generates a first illumination beam that is used to generate a first pattern beam that contains the first mask pattern;

a substrate stage assembly that retains and positions the substrate along the first axis; and

a control system that controls the illumination system, and the substrate stage assembly so that the first mask pattern is transferred to the first site while the substrate stage assembly is moving the substrate along the first axis.

2. The exposure apparatus of claim 1 further comprising a projection optical assembly that focuses the first pattern beam on the substrate; wherein the projection optical assembly includes a used field having a first field dimension along the first axis and a second field dimension along the second axis, wherein the first field dimension is smaller than the second field dimension.

3. The exposure apparatus of claim 2 wherein the first field dimension is shorter than the first site dimension and the second field dimension is equal to or greater than the second site dimension.

4. The exposure apparatus of claim 1 further comprising a first mask that includes the first mask pattern and a first mask stage assembly that retains and positions the first mask along the first axis relative to the first illumination beam, wherein the first pattern beam is created by directing the first illumination beam at the first mask pattern, and wherein the control system controls the first mask stage assembly so that the first mask stage assembly is moving the first mask along the first axis while the first mask pattern is being transferred to the first site.

5. The exposure apparatus of claim 4 further comprising a second mask stage assembly that retains and positions a second mask, wherein the illumination system generates a second illumination beam that is directed at the second mask, wherein the second illumination beam illuminates a second mask pattern of the second mask to generate a second pattern beam, and wherein the optical assembly focuses the first pattern beam and the second pattern beam on the substrate.

6. The exposure apparatus of claim 5 wherein the substrate further includes a second site, and wherein the control system controls the illumination system, the mask stage assemblies and the substrate stage assembly to transfer an image of the first mask pattern to the first site, and an image of the second mask pattern to the second site.

7. The exposure apparatus of claim 6 wherein the control system controls the substrate stage assembly to continuously move the substrate along the first axis when transferring the images to the first site and the second site.

8. The exposure apparatus of claim 7 wherein the control system controls the substrate stage assembly to move the substrate a movement step along the second axis after the second mask pattern is transferred to the second site.

9. The exposure apparatus of claim 4 wherein the control system controls the illumination system, the first mask stage assembly and the substrate stage assembly so that the entire first mask pattern is transferred to the first site while the first mask stage assembly is moving the first mask along the first axis, and the substrate stage assembly is moving the substrate along the first axis.

10. The exposure apparatus of claim 1 wherein the control system controls the substrate stage assembly to move the substrate a movement step along the second axis after the first mask pattern is transferred to the first site.

11. A process for manufacturing a wafer that includes the steps of providing a substrate having a first site and a second site, and transferring the first mask pattern to the first site and the second site of the substrate with the exposure apparatus of claim 1.

12. A method for transferring a first mask pattern to a substrate, the substrate including a first site having a first site dimension along a first axis and a second site dimension along a second axis that is perpendicular to the first axis, wherein the second site dimension is larger than the first site dimension, the method comprising the steps of:

directing a first pattern beam that contains the first mask pattern at the substrate;

positioning the substrate along the first axis with a substrate stage assembly; and

controlling the illumination system, and the substrate stage assembly with a control system so that the first mask pattern is transferred to the first site while the substrate stage assembly is moving the substrate along the first axis.

13. The method of claim 12 wherein the step of directing includes the steps of illuminating the first mask pattern with a first illumination beam from an illumination system to generate the first pattern beam, and focusing the first pattern beam on the substrate with an optical assembly.

14. The method of claim 13 wherein the step of focusing includes the optical assembly including a used field having a first field dimension along the first axis and a second field dimension along the second axis, wherein the first field dimension is smaller than the second field dimension.

15. The method of claim 14 wherein the step of focusing includes the first field dimension being shorter than the first site dimension and the second field dimension being equal to or greater than the second site dimension.

16. The method of claim 13 further comprising the steps of positioning a second mask with a second mask stage assembly, generating a second illumination beam that is directed at the second mask with the illumination system, illuminating a second mask pattern of the second mask with the second illumination beam to generate a second pattern beam, and focusing the first pattern beam and the second pattern beam on the substrate with the optical assembly.

17. The method of claim 16 wherein the substrate further includes a second site, and wherein the step of controlling includes the step of controlling the illumination system, the mask stage assemblies and the substrate stage assembly with the control system so that an image of the first mask pattern is transferred to the first site, and an image of the second mask pattern is transferred to the second site.

18. The method of claim 17 wherein the step of controlling includes the step of controlling the substrate stage assembly with the control system to continuously move the substrate along the first axis when transferring the images to the first site and the second site.

19. The method of claim 17 further comprising the step of moving the substrate a movement step along the second axis after the second mask pattern is transferred to the second site.

20. The method of claim 12 wherein the step of controlling includes the step of controlling the illumination system, and the substrate stage assembly with the control system so that the entire first mask pattern is transferred to the first site while the substrate stage assembly is moving the substrate along the first axis.

21. The method of claim 1 2 further comprising the step of controlling the substrate stage assembly with the control system to move the substrate a movement step along the second axis after the first mask pattern is transferred to the first site.