US20090027660A1 - Optical spot geometric parameter determination using calibration targets - Google Patents
Optical spot geometric parameter determination using calibration targets Download PDFInfo
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- US20090027660A1 US20090027660A1 US12/173,857 US17385708A US2009027660A1 US 20090027660 A1 US20090027660 A1 US 20090027660A1 US 17385708 A US17385708 A US 17385708A US 2009027660 A1 US2009027660 A1 US 2009027660A1
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- 230000004044 response Effects 0.000 claims description 12
- 230000007423 decrease Effects 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 230000001174 ascending effect Effects 0.000 claims description 3
- 238000005259 measurement Methods 0.000 abstract description 36
- 238000000034 method Methods 0.000 abstract description 31
- 230000009897 systematic effect Effects 0.000 abstract description 12
- 238000004590 computer program Methods 0.000 abstract description 5
- 238000004458 analytical method Methods 0.000 description 11
- 230000006870 function Effects 0.000 description 10
- 230000008569 process Effects 0.000 description 8
- 238000012545 processing Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 7
- 230000008859 change Effects 0.000 description 6
- 230000003247 decreasing effect Effects 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 238000003860 storage Methods 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000013500 data storage Methods 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000010365 information processing Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000003449 preventive effect Effects 0.000 description 1
- 238000012552 review Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
- G03F7/70491—Information management, e.g. software; Active and passive control, e.g. details of controlling exposure processes or exposure tool monitoring processes
- G03F7/70516—Calibration of components of the microlithographic apparatus, e.g. light sources, addressable masks or detectors
Definitions
- the present disclosure relates in general to a processing system, and more particularly to determining a geometric parameter of an optical spot of a light beam of an optical metrology tool used in the processing system.
- optical metrology Utilization of optical metrology in semiconductor manufacturing has grown significantly over the past several years.
- the technology provides capabilities to conduct measurements of a wide variety of critical device parameters, including, e.g., critical dimensions, depths and sidewall angles.
- Benefits of optical metrology include non-contact measurement capability that can be performed very quickly.
- optical metrology tools For optical metrology tools to yield reliable measurements, it is necessary that the tools produce well defined light beams, and collect the optical response for analysis, as designed.
- the size of the optical spot of the produced light beam which is defined as the area illuminated by the incident light beam, can have a large impact on the measurement values.
- the sizes of the optical spots of optical metrology tools affects the matching performance of the optical metrology tools.
- An optical spot can initially appear to be symmetric.
- An optical spot may have an area (usually referred to as an “effective spot”) inside the optical spot, which provides most, e.g., 99%, of the information content.
- An effective spot is very sensitive to the small change in the area it illuminates.
- an effective spot comprises a small portion of a total optical spot.
- the entire optical spot may illuminate an area of 1600 square microns, while the most sensitive area of the optical spot (i.e., the effective spot) may be a 100 square micron area. If the optical spot is symmetric, the effective spot will be located in the center of the optical spot. If the optical spot is not symmetric, then the effective spot will be located off the center of the optical spot. Whether an optical spot of an optical metrology tool is symmetric and the level of symmetry impact the measurement result and thus the matching of the optical metrology tools.
- a first aspect of the disclosure is directed to a method for determining a geometric parameter of an optical spot of a light beam, the method comprising: providing a calibration target, the calibration target including a systematic variation in a parameter; measuring the calibration target with respect to the systematic variation using the light beam to obtain a plurality of measurements; and analyzing the measurements and the systematic variation to determine the geometric parameter of the optical spot.
- a second aspect of the disclosure is directed to a system for determining a geometric parameter of an optical spot of a light beam, the method comprising:
- a third aspect of the disclosure is directed to a calibration target for measuring a size of an optical spot of a light beam, the calibration target comprising: a first portion, a dimension of which in a first axis systematically decreases along a second axis; a second portion; and a third portion; wherein the second portion and the third portion extend along opposite sides of the first portion and are separated by the first portion in the first axis, and include a material of different optical response than that of the first portion.
- a fourth aspect of the disclosure is directed to a calibration target for measuring a level of symmetry of an optical spot of a light beam, the calibration target comprising: a gradient in a parameter along an axis of the calibration target, the gradient being a function of the axis, and including one of: a continuous gradient from one end of the calibration target to another end thereof in the axis; or a switch point in a given point of the calibration target in the axis between two sub-gradients, one of the two sub-gradients being an ascending gradient and the other being a descending gradient.
- FIG. 1 shows a block diagram of a system according to the disclosure.
- FIGS. 2-3 show embodiments of calibration targets for measuring a size of an optical spot.
- FIG. 4 shows embodiments of a method for measuring the size of the optical spot using calibration targets of FIGS. 2-3 .
- FIG. 5-6 show embodiments of calibration targets for measuring a level of symmetry of an optical spot.
- FIG. 7 shows embodiments of a method for measuring the level of symmetry of the optical spot using calibration targets of FIGS. 5-6 .
- FIG. 1 shows a block diagram of a system 10 according to an embodiment of the invention.
- System 10 includes multiple optical metrology tools (tool) 12 . Each tool 12 can produce a light beam 14 having an optical spot 16 (shown in FIG. 2 ) on a calibration target 20 .
- System 10 includes a processing system 22 including a calibration target controlling unit 24 , a measurement controlling unit 26 , an analysis unit 28 including an optical response monitor 40 , a relative scan position adjusting unit 42 and an operation controlling unit 44 .
- System 10 also includes a tool matching unit 29 .
- FIG. 2 shows a calibration target 20 with multiple optical spots 16 thereon.
- Calibration target 20 includes a first portion 202 , a second portion 204 and a third portion 206 .
- Second portion 204 and third portion 206 extending along opposite sides 210 , 212 of first portion 202 , and are separated by first portion 202 in the y-axis.
- Second portion 204 and third portion 206 may further completely emborder first portion 202 (not shown).
- Second portion 204 and third portion 206 include a material of different optical response than that of first portion 202 such that when an optical spot 16 moves (partially or totally) from first portion 202 to at least one of second portion 204 or third portion 206 , a change will be detected in the reflected beam collected by, e.g., tool 12 .
- the optical response is substantially uniform.
- first portion 202 in y-axis systematically decreases along x-axis.
- systematic is used for its meaning in statistics and is opposite to “random”.
- a systematic variation is a non-random variation, e.g., continuous decreasing, continuous increasing, first increasing and then decreasing, gradient, etc.
- the decreasing of the y-axis dimension is in a continuous manner such that, in a two-dimensional view, first portion 202 has a substantially trapezoidal shape.
- a first portion 302 of a calibration target 30 in a two-dimensional view, has a substantially stepped-side trapezoidal shape, i.e., it has two ladder-shaped borders 310 , 312 .
- FIG. 4 shows, in a flow diagram, embodiments of a method for measuring a size of an optical spot 16 using calibration target 20 .
- calibration target 20 of FIG. 2 will be used as an example to describe the method of FIG. 4 .
- calibration target 30 of FIG. 3 may be similarly used.
- measurement controlling unit 26 and calibration target controlling unit 24 coordinate to control a tool 12 to measure calibration target 20 with respect to the systematic variation, i.e., the decreasing of the y-axis dimension, using the respective light beam 14 to obtain a plurality of measurements.
- the measuring includes scanning light beam 14 along calibration target 20 in x-axis to make measurements of the optical response of calibration target 20 .
- optical spot 16 is positioned to be totally within first portion 202 , as represented by optical spot 16 a , and the scanning may follow the x-axis along which the y-axis dimension of calibration target 20 decreases.
- optical spot 16 may be initially positioned to cover all three portions 202 , 204 and 206 , and the scanning may follow the direction that the y-axis dimension of calibration target 20 increases.
- analysis unit 28 analyzes the measurements and change of y-axis dimension of calibration target 20 to determine the size of optical spot 16 .
- analysis unit 28 relates a measurement of the optical response to a position of optical spot 16 with respect to first portion 202 , second portion 204 and third portion 206 of calibration target 20 to identify a reference scan position of optical spot 16 where optical spot 16 is marginally located within first portion 202 , i.e., optical spot 16 is substantially tangential to both borders 210 , 212 . That is, the “reference scan position” corresponds to a smallest y-axis dimension of first portion 202 that can still enclose optical spot 16 . Any method may be used to identify the reference scan position, and all are included.
- optical response monitor 40 detects a change of value in the measured calibration target 20 optical response indicating that optical spot 16 covers a portion of first portion 202 and a portion of at least one of second portion 204 and third portion 206 .
- Optical spot 16 b represents this situation.
- relative scan position adjusting unit 42 adjusts a relative position between optical spot 16 and the calibration target 20 in the y-axis to locate optical spot 16 within first portion 202 .
- relative scan position adjusting unit 42 may instruct calibration target controlling unit 24 to move calibration target 202 upward or may instruct measurement controlling unit 26 to move optical spot 16 b downward.
- operation controlling unit 44 determines whether the position-adjusted optical spot 16 is completely located within first portion 202 . If “yes”, operation controlling unit 44 proceeds to process S- 1 . That is, the scanning, detecting and adjusting is continued from the current scan position of optical spot 16 . If “no”, in sub-process S 2 - 4 , analysis unit 44 identifies the last scan position of optical spot 16 where optical spot 16 is located completely within first portion 202 as the reference scan position.
- analysis unit 28 determines a size of optical spot 16 in the y-axis based on the dimension of first portion 202 in the y-axis which corresponds to the reference scan position.
- the corresponding dimension is the largest y-axis dimension of first portion 202 from a point in border 210 or 212 of first portion 202 which is closest to optical spot 16 in the reference scan position.
- border point 46 and 48 are the closest points and dimension 50 is the corresponding dimension.
- FIG. 2 shows that the dimensions from border points 46 and 48 are the same, which is not necessary.
- dimensions from border points 46 and 48 may be different and the larger one will be identified as the corresponding dimension.
- the size of optical spot 16 in the y-axis will be determined as substantially equal to the corresponding dimension.
- size of optical spot 16 in other axis or direction may be determined.
- calibration target 20 may be rotated 90 degrees and optical spot 16 will be scanned along the y-axis to determine an x-axis size of optical spot 16 following the similarly procedures described above.
- analysis unit 28 may also determine a relative position between two optical spots 16 based on the adjusting in the y-axis made for each of the two optical spots 16 . As shown in FIG. 3 , e.g., if two optical spots 116 a and 116 b are adjusted differently (shown by different distances 118 a , 118 b ) in the y-axis to reach the respective reference scan positions, it is determined that centers 120 a and 120 b of optical spots 116 a and 116 b , as before adjustments, are separated from one another in the y-axis.
- processing system 22 may further determine a size of optical spot 16 using calibration targets with differences in another parameter different than the y-axis dimension to determine a variation of the determined size of optical spot 16 based on the difference in the another parameter. For example, processing system 22 may measure the size of optical spot 16 using calibration targets 20 of different combinations of optical responses, and/or critical dimensions to determine the possible variations in the measured sizes of optical spot 16 .
- FIG. 5 shows an embodiment of a calibration target 60 for measuring a level of symmetry of an optical spot 16 .
- Calibration target 60 includes a gradient 62 in a parameter along the x-axis.
- the gradient parameter may be any parameter whose change can be detected by the effective spot of optical spot 16 .
- the parameter may be optical response, critical dimensions, height or depth of grating line, etc.
- a density of grating lines 64 hereinafter “density” of calibration target 60 may be used for the gradient parameter.
- the density gradient is a function of the x-axis.
- the density gradient 62 is continuous from one end of calibration target 60 to another end thereof in the x-axis.
- the density gradient 162 includes two sub-gradients 162 a and 162 b separated by a switch point 166 in a given point in x-axis, e.g., in the center of calibration target 160 .
- sub-gradient 162 a is an ascending gradient (i.e., density increasing along the x-axis)
- sub-gradient 162 b is a descending one (i.e., density decreasing along the x-axis).
- FIG. 7 shows embodiments of a method for measuring a level of symmetry of optical spot 16 .
- a level of symmetry is determined based on whether the effective spot is in the center of the optical spot and how far away the effective spot deviates from the center of the optical spot.
- measurement controlling unit 26 locates optical spot 16 with an effective spot 17 on a given point, e.g., the center 66 , and scans optical spot 16 from the given point along gradient 62 or 162 in different directions to obtain multiple measurements of the density.
- analysis unit 28 analyzes the differences in the measured density to determine whether effective spot 17 is in the center of optical spot 16 , and/or how far away effective spot 17 deviates from the center of optical spot 16 . Any method may be used in the analysis, and all are included. For example, where calibration target 60 is used for the measurement, measurement controlling unit 26 may scan optical spot 16 from center 66 to the low density end 68 (as shown by arrow 67 ) along the x-axis and obtain a first set of measurements. Then, calibration target controlling unit 24 may position calibration target 60 with a 180 degree rotation as shown in phantom 60 a .
- Measurement controlling unit 26 may scan optical spot 16 from center 66 to the low density end 68 (as shown by dotted arrow 67 a along the x-axis) and obtain a second set of measurements. If the second set of measurements does not match the first set of measurements, it can be determined that effective spot 17 is not located in the center of optical spot 16 .
- calibration target controlling unit 24 may position calibration target 60 with a 90 degree rotation as shown in phantom 60 b .
- Measurement controlling unit 26 may scan optical spot 16 from center 66 to the low density end 68 (as shown by dotted arrow 67 b along the z-axis) and obtain a third set of measurements.
- analysis unit 28 may be able to determine how far away effective spot 17 deviates from the center of optical spot 16 .
- measurement controlling unit 26 may first locate optical spot 16 in the center 166 of calibration target 160 and scan optical spot 16 from center 166 to both sides along sub-gradient 162 a and 162 b in x-axis. If measurements from both sides of the scanning show increases in the density, it is determined that the effective spot 17 ( FIG. 5 ) is in the center of optical spot 16 ( FIG. 5 ). If measurements from one side of scanning show a switch point (e.g., change from density decreasing to density increasing) in the density, it is determined that the effective spot 17 ( FIG. 5 ) is not in the center of optical spot 16 ( FIG. 5 ). In addition, by relating the detected switch point to the scan position of optical spot 16 , analysis unit 28 may be able to determine how far away effective spot 17 ( FIG. 5 ) deviates from the center of optical spot 16 ( FIG. 5 ).
- switch point e.g., change from density decreasing to density increasing
- the determined geometric parameter of optical spot 16 may be output to, e.g., tool matching unit 29 for matching tools 12 based on the respective optical spot 16 geometric parameters.
- tool matching unit 29 may adjust the measurements of each tools 12 based on the respective sizes and/or levels of symmetry of optical spots 16 .
- Tool matching unit 29 may also physically adjust each tool 12 regarding the optical spot 16 geometric parameters.
- Other uses of the determined sizes and/or levels of symmetry of light beams 14 of tools 12 are also possible and included in the disclosure.
- the calibration targets described above may be used in a semi real time feedback control system to measure geometric parameters of optical spots during system manufacturing, optics alignment and preventive maintenance.
- processing system 22 may be implemented by a computer system.
- the computer system can comprise any general purpose computing article of manufacture capable of executing computer program code installed thereon to perform the process described herein.
- the computer system can also comprise any specific purpose computing article of manufacture comprising hardware and/or computer program code for performing specific functions, any computing article of manufacture that comprises a combination of specific purpose and general purpose hardware or software, or the like.
- the program code and hardware can be created using standard programming and engineering techniques, respectively.
- the disclosure provides a program product stored on a computer-readable medium, which when executed, enables a computer infrastructure to determine a geometric parameter of an optical spot of a light beam.
- the computer-readable medium includes program code, which may be installed to a computer system to implement, e.g., processing system 22 ( FIG. 1 ), to implement the process described herein.
- the term “computer-readable medium” comprises one or more of any type of physical embodiment of the program code.
- the computer-readable medium can comprise program code embodied on one or more portable storage articles of manufacture (e.g., a compact disc, a magnetic disk, a tape, etc.), on one or more data storage portions of a computing device, such as a memory and/or a storage system and/or as a data signal traveling over a network (e.g., during a wired or wireless electronic distribution of the program product).
- portable storage articles of manufacture e.g., a compact disc, a magnetic disk, a tape, etc.
- data storage portions of a computing device such as a memory and/or a storage system and/or as a data signal traveling over a network (e.g., during a wired or wireless electronic distribution of the program product).
- a system 10 including processing system 22 and calibration targets 20 , 30 , 60 and 160 could be created, maintained and/or deployed by a service provider that offers the functions described herein for customers. That is, a service provider could offer to determine a geometric parameter of an optical spot of a light beam as described above.
- program code and “computer program code” are synonymous and mean any expression, in any language, code or notation, of a set of instructions that cause a computing device having an information processing capability to perform a particular function either directly or after any combination of the following: (a) conversion to another language, code or notation; (b) reproduction in a different material form; and or or (c) decompression.
- program code can be embodied as one or more types of program products, such as an application or software program, component software or a library of functions, an operating system, a basic I or O system or driver for a particular computing and/or I or O device, and the like.
- component and “system” are synonymous as used herein and represent any combination of hardware and/or software capable of performing some function(s).
- each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s).
- the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.
Abstract
Description
- This application is a continuation application of co-pending U.S. patent application Ser. No. 11/828,666 filed on Jul. 26, 2007, which is hereby incorporated by reference.
- 1. Technical Field
- The present disclosure relates in general to a processing system, and more particularly to determining a geometric parameter of an optical spot of a light beam of an optical metrology tool used in the processing system.
- 2. Background Art
- Utilization of optical metrology in semiconductor manufacturing has grown significantly over the past several years. The technology provides capabilities to conduct measurements of a wide variety of critical device parameters, including, e.g., critical dimensions, depths and sidewall angles. Benefits of optical metrology include non-contact measurement capability that can be performed very quickly.
- For optical metrology tools to yield reliable measurements, it is necessary that the tools produce well defined light beams, and collect the optical response for analysis, as designed. The size of the optical spot of the produced light beam, which is defined as the area illuminated by the incident light beam, can have a large impact on the measurement values. As a consequence, for example, the sizes of the optical spots of optical metrology tools affects the matching performance of the optical metrology tools.
- An optical spot can initially appear to be symmetric. An optical spot may have an area (usually referred to as an “effective spot”) inside the optical spot, which provides most, e.g., 99%, of the information content. An effective spot is very sensitive to the small change in the area it illuminates. Usually, an effective spot comprises a small portion of a total optical spot. For example, the entire optical spot may illuminate an area of 1600 square microns, while the most sensitive area of the optical spot (i.e., the effective spot) may be a 100 square micron area. If the optical spot is symmetric, the effective spot will be located in the center of the optical spot. If the optical spot is not symmetric, then the effective spot will be located off the center of the optical spot. Whether an optical spot of an optical metrology tool is symmetric and the level of symmetry impact the measurement result and thus the matching of the optical metrology tools.
- Conventional approaches to optical metrology do not have a satisfactory solution to characterize a geometric parameter of an optical spot and or or a level of symmetry of the optical spot.
- A first aspect of the disclosure is directed to a method for determining a geometric parameter of an optical spot of a light beam, the method comprising: providing a calibration target, the calibration target including a systematic variation in a parameter; measuring the calibration target with respect to the systematic variation using the light beam to obtain a plurality of measurements; and analyzing the measurements and the systematic variation to determine the geometric parameter of the optical spot.
- A second aspect of the disclosure is directed to a system for determining a geometric parameter of an optical spot of a light beam, the method comprising:
- means for controlling a calibration target, the calibration target including a systematic variation in a parameter; means for measuring the calibration target with respect to the systematic variation using the light beam to obtain a plurality of measurements; and means for analyzing the measurements and the systematic variation to determine the geometric parameter of the optical spot.
- A third aspect of the disclosure is directed to a calibration target for measuring a size of an optical spot of a light beam, the calibration target comprising: a first portion, a dimension of which in a first axis systematically decreases along a second axis; a second portion; and a third portion; wherein the second portion and the third portion extend along opposite sides of the first portion and are separated by the first portion in the first axis, and include a material of different optical response than that of the first portion.
- A fourth aspect of the disclosure is directed to a calibration target for measuring a level of symmetry of an optical spot of a light beam, the calibration target comprising: a gradient in a parameter along an axis of the calibration target, the gradient being a function of the axis, and including one of: a continuous gradient from one end of the calibration target to another end thereof in the axis; or a switch point in a given point of the calibration target in the axis between two sub-gradients, one of the two sub-gradients being an ascending gradient and the other being a descending gradient.
- Other aspects and features of the present disclosure, as defined solely by the claims, will become apparent to those ordinarily skilled in the art upon review of the following non-limited detailed description of the disclosure in conjunction with the accompanying figures.
- The embodiments of this disclosure will be described in detail, with reference to the following figures, wherein like designations denote like elements, and wherein:
-
FIG. 1 shows a block diagram of a system according to the disclosure. -
FIGS. 2-3 show embodiments of calibration targets for measuring a size of an optical spot. -
FIG. 4 shows embodiments of a method for measuring the size of the optical spot using calibration targets ofFIGS. 2-3 . -
FIG. 5-6 show embodiments of calibration targets for measuring a level of symmetry of an optical spot. -
FIG. 7 shows embodiments of a method for measuring the level of symmetry of the optical spot using calibration targets ofFIGS. 5-6 . - It is noted that the drawings of the disclosure are not to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the disclosure. In the drawings, like numbering represents like elements among the drawings.
- The following detailed description of embodiments refers to the accompanying drawings, which illustrate specific embodiments of the disclosure. Other embodiments having different structures and operations do not depart from the scope of the present disclosure.
-
FIG. 1 shows a block diagram of asystem 10 according to an embodiment of the invention.System 10 includes multiple optical metrology tools (tool) 12. Eachtool 12 can produce alight beam 14 having an optical spot 16 (shown inFIG. 2 ) on acalibration target 20.System 10 includes aprocessing system 22 including a calibrationtarget controlling unit 24, ameasurement controlling unit 26, ananalysis unit 28 including anoptical response monitor 40, a relative scanposition adjusting unit 42 and anoperation controlling unit 44.System 10 also includes atool matching unit 29. -
FIG. 2 shows acalibration target 20 with multipleoptical spots 16 thereon.Calibration target 20 includes afirst portion 202, asecond portion 204 and athird portion 206.Second portion 204 andthird portion 206 extending alongopposite sides 210, 212 offirst portion 202, and are separated byfirst portion 202 in the y-axis.Second portion 204 andthird portion 206 may further completely emborder first portion 202 (not shown).Second portion 204 andthird portion 206 include a material of different optical response than that offirst portion 202 such that when anoptical spot 16 moves (partially or totally) fromfirst portion 202 to at least one ofsecond portion 204 orthird portion 206, a change will be detected in the reflected beam collected by, e.g.,tool 12. Within each portion, the optical response is substantially uniform. - An y-axis dimension of
first portion 202 in y-axis systematically decreases along x-axis. In this description, the term “systematic” is used for its meaning in statistics and is opposite to “random”. A systematic variation is a non-random variation, e.g., continuous decreasing, continuous increasing, first increasing and then decreasing, gradient, etc. According to an embodiment, as shown inFIG. 2 , the decreasing of the y-axis dimension is in a continuous manner such that, in a two-dimensional view,first portion 202 has a substantially trapezoidal shape. According to an alternative embodiment, as shown inFIG. 3 , in a two-dimensional view, afirst portion 302 of acalibration target 30 has a substantially stepped-side trapezoidal shape, i.e., it has two ladder-shaped borders -
FIG. 4 shows, in a flow diagram, embodiments of a method for measuring a size of anoptical spot 16 usingcalibration target 20. In the following description,calibration target 20 ofFIG. 2 will be used as an example to describe the method ofFIG. 4 . It should be appreciated thatcalibration target 30 ofFIG. 3 may be similarly used. Referring toFIGS. 1-2 and 4 collectively, in process S1,measurement controlling unit 26 and calibrationtarget controlling unit 24 coordinate to control atool 12 to measurecalibration target 20 with respect to the systematic variation, i.e., the decreasing of the y-axis dimension, using therespective light beam 14 to obtain a plurality of measurements. Specifically, the measuring includesscanning light beam 14 alongcalibration target 20 in x-axis to make measurements of the optical response ofcalibration target 20. For example, at the beginning of the scan,optical spot 16 is positioned to be totally withinfirst portion 202, as represented byoptical spot 16 a, and the scanning may follow the x-axis along which the y-axis dimension ofcalibration target 20 decreases. However, other scanning procedure is also possible. For example,optical spot 16 may be initially positioned to cover all threeportions calibration target 20 increases. - In process S2,
analysis unit 28 analyzes the measurements and change of y-axis dimension ofcalibration target 20 to determine the size ofoptical spot 16. Specifically,analysis unit 28 relates a measurement of the optical response to a position ofoptical spot 16 with respect tofirst portion 202,second portion 204 andthird portion 206 ofcalibration target 20 to identify a reference scan position ofoptical spot 16 whereoptical spot 16 is marginally located withinfirst portion 202, i.e.,optical spot 16 is substantially tangential to bothborders 210, 212. That is, the “reference scan position” corresponds to a smallest y-axis dimension offirst portion 202 that can still encloseoptical spot 16. Any method may be used to identify the reference scan position, and all are included. For example, according to an embodiment, in sub-process S2-1, optical response monitor 40 detects a change of value in the measuredcalibration target 20 optical response indicating thatoptical spot 16 covers a portion offirst portion 202 and a portion of at least one ofsecond portion 204 andthird portion 206.Optical spot 16 b represents this situation. - In sub-process S2-2, relative scan
position adjusting unit 42 adjusts a relative position betweenoptical spot 16 and thecalibration target 20 in the y-axis to locateoptical spot 16 withinfirst portion 202. For example, with respect tooptical spot 16 b, relative scanposition adjusting unit 42 may instruct calibrationtarget controlling unit 24 to movecalibration target 202 upward or may instructmeasurement controlling unit 26 to moveoptical spot 16 b downward. - In sub-process S2-3,
operation controlling unit 44 determines whether the position-adjustedoptical spot 16 is completely located withinfirst portion 202. If “yes”,operation controlling unit 44 proceeds to process S-1. That is, the scanning, detecting and adjusting is continued from the current scan position ofoptical spot 16. If “no”, in sub-process S2-4,analysis unit 44 identifies the last scan position ofoptical spot 16 whereoptical spot 16 is located completely withinfirst portion 202 as the reference scan position. - In process S3,
analysis unit 28 determines a size ofoptical spot 16 in the y-axis based on the dimension offirst portion 202 in the y-axis which corresponds to the reference scan position. The corresponding dimension is the largest y-axis dimension offirst portion 202 from a point inborder 210 or 212 offirst portion 202 which is closest tooptical spot 16 in the reference scan position. For example, foroptical spot 16 c ofFIG. 2 ,border point dimension 50 is the corresponding dimension.FIG. 2 shows that the dimensions fromborder points optical spot 16 is not symmetric, dimensions fromborder points optical spot 16 in the y-axis will be determined as substantially equal to the corresponding dimension. - Following the similar procedure, size of
optical spot 16 in other axis or direction may be determined. For example,calibration target 20 may be rotated 90 degrees andoptical spot 16 will be scanned along the y-axis to determine an x-axis size ofoptical spot 16 following the similarly procedures described above. - According to an embodiment,
analysis unit 28 may also determine a relative position between twooptical spots 16 based on the adjusting in the y-axis made for each of the twooptical spots 16. As shown inFIG. 3 , e.g., if twooptical spots different distances centers optical spots - In addition,
processing system 22 may further determine a size ofoptical spot 16 using calibration targets with differences in another parameter different than the y-axis dimension to determine a variation of the determined size ofoptical spot 16 based on the difference in the another parameter. For example,processing system 22 may measure the size ofoptical spot 16 usingcalibration targets 20 of different combinations of optical responses, and/or critical dimensions to determine the possible variations in the measured sizes ofoptical spot 16. -
FIG. 5 shows an embodiment of acalibration target 60 for measuring a level of symmetry of anoptical spot 16.Calibration target 60 includes agradient 62 in a parameter along the x-axis. The gradient parameter may be any parameter whose change can be detected by the effective spot ofoptical spot 16. For example, the parameter may be optical response, critical dimensions, height or depth of grating line, etc. In the current description, a density of grating lines 64 (hereinafter “density”) ofcalibration target 60 may be used for the gradient parameter. Preferably, the density gradient is a function of the x-axis. - According to an embodiment, as shown in
FIG. 5 , thedensity gradient 62 is continuous from one end ofcalibration target 60 to another end thereof in the x-axis. According to an another embodiment, as shown inFIG. 6 , thedensity gradient 162 includes twosub-gradients switch point 166 in a given point in x-axis, e.g., in the center ofcalibration target 160. Along the x-axis, sub-gradient 162 a is an ascending gradient (i.e., density increasing along the x-axis), and sub-gradient 162 b is a descending one (i.e., density decreasing along the x-axis). -
FIG. 7 shows embodiments of a method for measuring a level of symmetry ofoptical spot 16. A level of symmetry is determined based on whether the effective spot is in the center of the optical spot and how far away the effective spot deviates from the center of the optical spot. Referring toFIGS. 1 , 5 and 7, in process S11,measurement controlling unit 26 locatesoptical spot 16 with aneffective spot 17 on a given point, e.g., thecenter 66, and scansoptical spot 16 from the given point alonggradient analysis unit 28 analyzes the differences in the measured density to determine whethereffective spot 17 is in the center ofoptical spot 16, and/or how far awayeffective spot 17 deviates from the center ofoptical spot 16. Any method may be used in the analysis, and all are included. For example, wherecalibration target 60 is used for the measurement,measurement controlling unit 26 may scanoptical spot 16 fromcenter 66 to the low density end 68 (as shown by arrow 67) along the x-axis and obtain a first set of measurements. Then, calibrationtarget controlling unit 24 may positioncalibration target 60 with a 180 degree rotation as shown inphantom 60 a.Measurement controlling unit 26 may scanoptical spot 16 fromcenter 66 to the low density end 68 (as shown by dottedarrow 67 a along the x-axis) and obtain a second set of measurements. If the second set of measurements does not match the first set of measurements, it can be determined thateffective spot 17 is not located in the center ofoptical spot 16. Alternatively, calibrationtarget controlling unit 24 may positioncalibration target 60 with a 90 degree rotation as shown inphantom 60 b.Measurement controlling unit 26 may scanoptical spot 16 fromcenter 66 to the low density end 68 (as shown by dottedarrow 67 b along the z-axis) and obtain a third set of measurements. If the third set of measurements does not match the first set of measurements, it can be determined thateffective spot 17 is not located in the center ofoptical spot 16. In addition, by comparing the differences in the different sets of measurement,analysis unit 28 may be able to determine how far awayeffective spot 17 deviates from the center ofoptical spot 16. - Referring to FIGS. 1 and 6-7, where
calibration target 160 is used,measurement controlling unit 26 may first locateoptical spot 16 in thecenter 166 ofcalibration target 160 and scanoptical spot 16 fromcenter 166 to both sides along sub-gradient 162 a and 162 b in x-axis. If measurements from both sides of the scanning show increases in the density, it is determined that the effective spot 17 (FIG. 5 ) is in the center of optical spot 16 (FIG. 5 ). If measurements from one side of scanning show a switch point (e.g., change from density decreasing to density increasing) in the density, it is determined that the effective spot 17 (FIG. 5 ) is not in the center of optical spot 16 (FIG. 5 ). In addition, by relating the detected switch point to the scan position ofoptical spot 16,analysis unit 28 may be able to determine how far away effective spot 17 (FIG. 5 ) deviates from the center of optical spot 16 (FIG. 5 ). - The determined geometric parameter of
optical spot 16, e.g., size, level of symmetry, may be output to, e.g.,tool matching unit 29 for matchingtools 12 based on the respectiveoptical spot 16 geometric parameters. For example,tool matching unit 29 may adjust the measurements of eachtools 12 based on the respective sizes and/or levels of symmetry ofoptical spots 16.Tool matching unit 29 may also physically adjust eachtool 12 regarding theoptical spot 16 geometric parameters. Other uses of the determined sizes and/or levels of symmetry oflight beams 14 oftools 12 are also possible and included in the disclosure. For example, the calibration targets described above may be used in a semi real time feedback control system to measure geometric parameters of optical spots during system manufacturing, optics alignment and preventive maintenance. - According to an embodiment,
processing system 22 may be implemented by a computer system. The computer system can comprise any general purpose computing article of manufacture capable of executing computer program code installed thereon to perform the process described herein. The computer system can also comprise any specific purpose computing article of manufacture comprising hardware and/or computer program code for performing specific functions, any computing article of manufacture that comprises a combination of specific purpose and general purpose hardware or software, or the like. In each case, the program code and hardware can be created using standard programming and engineering techniques, respectively. - While shown and described herein as a method and system for determining a geometric parameter of an optical spot of a light beam, it is understood that the disclosure further provides various alternative embodiments. For example, in an embodiment, the disclosure provides a program product stored on a computer-readable medium, which when executed, enables a computer infrastructure to determine a geometric parameter of an optical spot of a light beam. To this extent, the computer-readable medium includes program code, which may be installed to a computer system to implement, e.g., processing system 22 (
FIG. 1 ), to implement the process described herein. It is understood that the term “computer-readable medium” comprises one or more of any type of physical embodiment of the program code. In particular, the computer-readable medium can comprise program code embodied on one or more portable storage articles of manufacture (e.g., a compact disc, a magnetic disk, a tape, etc.), on one or more data storage portions of a computing device, such as a memory and/or a storage system and/or as a data signal traveling over a network (e.g., during a wired or wireless electronic distribution of the program product). - It should be appreciated that the teachings of the present disclosure could be offered as a business method on a subscription or fee basis. For example, a system 10 (
FIG. 1 ) includingprocessing system 22 andcalibration targets - As used herein, it is understood that the terms “program code” and “computer program code” are synonymous and mean any expression, in any language, code or notation, of a set of instructions that cause a computing device having an information processing capability to perform a particular function either directly or after any combination of the following: (a) conversion to another language, code or notation; (b) reproduction in a different material form; and or or (c) decompression. To this extent, program code can be embodied as one or more types of program products, such as an application or software program, component software or a library of functions, an operating system, a basic I or O system or driver for a particular computing and/or I or O device, and the like. Further, it is understood that the terms “component” and “system” are synonymous as used herein and represent any combination of hardware and/or software capable of performing some function(s).
- The flowcharts and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and or or flowchart illustration, and combinations of blocks in the block diagrams and or or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
- The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
- Although specific embodiments have been illustrated and described herein, those of ordinary skill in the art appreciate that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiments shown and that the disclosure has other applications in other environments. This application is intended to cover any adaptations or variations of the present disclosure. The following claims are in no way intended to limit the scope of the disclosure to the specific embodiments described herein.
Claims (2)
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US12/173,857 US20090027660A1 (en) | 2006-07-25 | 2008-07-16 | Optical spot geometric parameter determination using calibration targets |
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EP06117795 | 2006-07-25 | ||
US11/828,666 US7477365B2 (en) | 2006-07-25 | 2007-07-26 | Optical spot geometric parameter determination using calibration targets |
US12/173,857 US20090027660A1 (en) | 2006-07-25 | 2008-07-16 | Optical spot geometric parameter determination using calibration targets |
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US11/828,666 Continuation US7477365B2 (en) | 2006-07-25 | 2007-07-26 | Optical spot geometric parameter determination using calibration targets |
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US11/828,666 Expired - Fee Related US7477365B2 (en) | 2006-07-25 | 2007-07-26 | Optical spot geometric parameter determination using calibration targets |
US12/173,857 Abandoned US20090027660A1 (en) | 2006-07-25 | 2008-07-16 | Optical spot geometric parameter determination using calibration targets |
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US11/828,666 Expired - Fee Related US7477365B2 (en) | 2006-07-25 | 2007-07-26 | Optical spot geometric parameter determination using calibration targets |
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Publication number | Priority date | Publication date | Assignee | Title |
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US8207759B2 (en) | 2009-03-12 | 2012-06-26 | Fairchild Semiconductor Corporation | MIPI analog switch for automatic selection of multiple inputs based on clock voltages |
US9314632B2 (en) | 2012-05-17 | 2016-04-19 | Boston Scientific Neuromodulation Corporation | Pulse-by-pulse compliance voltage generation for an implantable stimulator |
US9568504B2 (en) | 2013-03-15 | 2017-02-14 | Milwaukee Electric Tool Corporation | Digital multi-meter |
US9958327B2 (en) * | 2014-10-01 | 2018-05-01 | Nanometrics Incorporated | Deconvolution to reduce the effective spot size of a spectroscopic optical metrology device |
US10090674B2 (en) * | 2015-09-21 | 2018-10-02 | Silicon Laboratories Inc. | Maximum supply voltage selection |
US10355477B2 (en) * | 2015-10-30 | 2019-07-16 | Silicon Laboratories Inc. | Digital signal transfer between multiple voltage domains |
KR102501696B1 (en) * | 2018-06-18 | 2023-02-21 | 에스케이하이닉스 주식회사 | Voltage clamping circuit, semiconductor apparatus and semiconductor system including the same |
US20220308468A1 (en) * | 2019-07-08 | 2022-09-29 | Asml Netherlands B.V. | Method for determining a center of a radiation spot, sensor and stage apparatus |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4269103A (en) * | 1976-02-11 | 1981-05-26 | Underwood John F | Electromagnetic pickup for stringed musical instruments |
US5144498A (en) * | 1990-02-14 | 1992-09-01 | Hewlett-Packard Company | Variable wavelength light filter and sensor system |
US6008920A (en) * | 1998-03-11 | 1999-12-28 | Optical Coating Laboratory, Inc. | Multiple channel multiplexer/demultiplexer devices |
US20060039009A1 (en) * | 2004-08-23 | 2006-02-23 | Palo Alto Research Center Incorporated | Chip-size wavelength detector |
US7345764B2 (en) * | 2005-02-07 | 2008-03-18 | Vladimir Bulovic | Apparatus and method for a slim format spectrometer |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5864587A (en) * | 1995-06-06 | 1999-01-26 | Lsi Logic Corporation | Differential signal receiver |
US5889419A (en) * | 1996-11-01 | 1999-03-30 | Lucent Technologies Inc. | Differential comparison circuit having improved common mode range |
JP3558844B2 (en) * | 1997-11-28 | 2004-08-25 | シャープ株式会社 | Sense amplifier circuit |
JP3589557B2 (en) * | 1997-12-24 | 2004-11-17 | シャープ株式会社 | Sense amplifier circuit |
US6111437A (en) * | 1998-05-29 | 2000-08-29 | Lucent Technologies Inc. | Wide common-mode differential receiver with precision input referred offset |
-
2007
- 2007-07-25 US US11/782,910 patent/US20080048729A1/en not_active Abandoned
- 2007-07-26 US US11/828,666 patent/US7477365B2/en not_active Expired - Fee Related
-
2008
- 2008-07-16 US US12/173,857 patent/US20090027660A1/en not_active Abandoned
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4269103A (en) * | 1976-02-11 | 1981-05-26 | Underwood John F | Electromagnetic pickup for stringed musical instruments |
US5144498A (en) * | 1990-02-14 | 1992-09-01 | Hewlett-Packard Company | Variable wavelength light filter and sensor system |
US6008920A (en) * | 1998-03-11 | 1999-12-28 | Optical Coating Laboratory, Inc. | Multiple channel multiplexer/demultiplexer devices |
US20060039009A1 (en) * | 2004-08-23 | 2006-02-23 | Palo Alto Research Center Incorporated | Chip-size wavelength detector |
US7310153B2 (en) * | 2004-08-23 | 2007-12-18 | Palo Alto Research Center, Incorporated | Using position-sensitive detectors for wavelength determination |
US7345764B2 (en) * | 2005-02-07 | 2008-03-18 | Vladimir Bulovic | Apparatus and method for a slim format spectrometer |
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US20080024781A1 (en) | 2008-01-31 |
US7477365B2 (en) | 2009-01-13 |
US20080048729A1 (en) | 2008-02-28 |
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