US20030194955A1

US20030194955A1 - Conditioner and conditioning methods for smooth pads

Info

Publication number: US20030194955A1
Application number: US10/397,974
Authority: US
Inventors: Thomas West; Guangwei Wu; Donald Dietz
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-03-25
Filing date: 2003-03-25
Publication date: 2003-10-16
Also published as: WO2003082519B1; WO2003082519A1; US20030181155A1; US7118461B2; AU2003226023A1; AU2003225999A1; WO2003082524A1; TW200305482A; TWI260256B; TW200305483A

Abstract

Pad conditioners and methods of conditioning pads for applications such as polishing substrates and chemical mechanical planarization of substrates are provided.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. patent application Ser. No. 60/368,048 filed Mar. 25, 2002 and U.S. patent application Ser. No. 60/368,049 filed Mar. 25, 2002. This application is related to U.S. patent application Ser. No. 10/020,081, filed Dec. 11, 2001, and U.S. patent application Ser. No. 10/020,082, filed Dec. 11, 2001. The contents of all of these applications are incorporated herein by this reference in their entirety.[0001]

TECHNICAL FIELD

This invention relates to conditioners and methods for conditioning pads for applications such as chemical mechanical planarization (CMP) and polishing of substrates such as semiconductor substrates, wafers, metallurgical samples, memory disk surfaces, optical components, lenses, and wafer masks. More particularly, the present invention relates to conditioners for CMP pads and pads for polishing and methods of maintaining pads during CMP and polishing processes for fabrication of electronic devices.

BACKGROUND

Processes employing CMP or polishing techniques have been widely used to planarize the surface of wafers during the various stages of device fabrication in order to improve yield, performance, and reliability of the fabrication process. In fact, CMP has become essentially indispensable on behalf of the fabrication of advanced integrated circuits.

Integrated circuits are chemically and physically integrated into a substrate by patterning regions in the substrate and layers on the substrate. To achieve high yields, it is usually necessary to recreate a substantially flat substrate after processing steps that leave topographic features on the surface of the wafer, features such as surface irregularities, bumps, troughs, and trenches.

One type of commonly used pad for applications such as polishing and CMP of substrates is a fiber pad such as a felt pad. The felt pad is a composite of fibers impregnated with a resin. Felt pads offer many unique advantages compared to non-fiber pads like pure polyurethane pads. Some examples of the advantages are low cost of ownership and good non-uniformity for the CMP process. However, the standard methods of pad conditioning and the standard materials for pad conditioning may be unsuitable for use with fiber CMP pads such as felt pads. Particularly, the standard conditioning methods and materials are not easily adopted for use with fiber based pads because the combination does not allow for good planarization efficiency.

There is a need for improved pad conditioners and improved methods for conditioning pads such as fiber pads like resin impregnated felt pads. More particularly, there is a need for improved pad conditioners and methods of pad conditioning for resin impregnated felt pads so that the pads can perform with higher planarization efficiencies. In addition, there is a need for new pad conditioners and conditioning methods that allow the pad to be used for longer periods of time before the pad must be replaced.

SUMMARY

This invention pertains to improve pad conditioners and methods of conditioning pads for applications such as polishing substrates and CMP of substrates and related methods. The present invention seeks to overcome one or more of the deficiencies of the standard technologies for polishing and/or planarizing substrates.

One aspect of the present invention includes a pad conditioner for applications such as polishing substrates and CMP of substrates. An embodiment of the present invention is a pad conditioner for CMP of substrates for electronic device fabrication. Another aspect of the present invention is a method for conditioning pads for applications such as polishing substrates and CMP of substrates.

Still another aspect of the present invention includes an apparatus for applications such as polishing substrates and CMP of substrates. In one embodiment, the apparatus includes a support for holding a pad for polishing substrates and/or CMP of substrates. The apparatus further includes a pad conditioner according to the teachings of the present disclosure.

It is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the figures. The invention is capable of other embodiments and of being practiced and carried out in various ways. In addition, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out aspects of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

Further, the purpose of the foregoing abstract is to enable the Patent Office and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The abstract is not intended to define the invention of the application, which is measured by the claims, nor is the abstract intended to be limiting as to the scope of the invention in any way.

The above and still further features and advantages of the present invention will become apparent upon consideration of the following detailed descriptions of specific embodiments thereof, especially when taken in conjunction with the accompanying figures.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of an embodiment of the present invention. [0014]
FIG. 2 is a diagram of an embodiment of the present invention. [0015]
FIG. 3 is a diagram of an embodiment of the present invention. [0016]
FIG. 4 is a diagram of an embodiment of the present invention.[0017]
Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention. [0018]

DESCRIPTION

The operation of embodiments of the present invention will be discussed below, primarily, in the context of chemical mechanical planarization of substrates for electronic devices. However, it is to be understood that embodiments in accordance with the present invention may be used for general applications such as CMP and substrate polishing such as grinding, lapping, shaping and polishing of semiconductor substrates, wafers, metallurgical samples, memory disk surfaces, optical components, lenses, and wafer masks. [0019]
An embodiment of the present invention is an improved polishing pad conditioner for substantially maintaining polishing pad performance. More particularly, one embodiment of the present invention is a polishing pad conditioner for applications such as chemical mechanical planarization such as that used as part of integrated circuit manufacturing processes. Another embodiment of the present invention includes methods for performing chemical mechanical planarization. [0020]
Embodiments of the present invention are particularly suitable for use with an improved polishing pad for applications such as chemical mechanical planarization. One embodiment of the present invention is a pad conditioner for chemical mechanical planarization of substrates for electronic device fabrication; the pad conditioner maintains the polishing surface of a fiber pad sufficiently smooth so that the pad is capable of providing effective planarization. In other words, pad conditioners according to embodiments the present invention are capable of conditioning pads that are capable of providing planarization efficiencies that are suitable for industrial processes such as chemical mechanical planarization. Preferably, the planarization efficiencies are high enough to meet the specifications for processing the work pieces. [0021]
Reference is now made to FIG. 1 where there is shown a side view of an embodiment of a [0022] pad conditioner 15 according to the present invention. Pad conditioner 15 includes a conditioner body 20 having a conditioning surface 25. Conditioning surface 25 includes an abrasive surface for abrading the polishing surface of a pad for applications such as chemical mechanical planarization and polishing substrates.
Pad conditioners according to embodiments of the present invention have physical features different from those of standard conditioners. Conditioning [0023] surface 25 comprises abrasive particles. Optionally, conditioner body 20 may include a metal disk where one side of the disk comprises conditioning surface 25 (see FIG. 2). The particles may be directly bonded to conditioning surface 25 of conditioner body 20. For embodiments of the present invention, the particles have a grit greater than about 200. More preferably, the particle grit is greater than about 300 and for some applications greater than 400.
In some embodiments of the present invention, the particles have sizes in the range of the about 1 micrometer to about 50 micrometers and all ranges subsumed therein. One embodiment of the present invention includes a pad conditioner that comprises abrasive particles bonded to a carrier and the particles are less than about 30 micrometers in size. For some applications, a more preferred embodiment of the conditioner comprises abrasive particles bonded to a carrier and the particles are less than are about 15 micrometers in size. [0024]
For some embodiments of the present invention, the spacing between the particles is also important. For some embodiments of the present invention, the particles have nearest neighbors spacings less than about 4 times the size of the particles. Preferably, the average nearest neighbor spacing between the particles is in the range of about 4 times the size of the particles to about 0 and all subranges subsumed therein. In one embodiment, the particles have an average nearest neighbor spacing less than about 3 times the size of the particles. In yet another embodiment, the particles have an average nearest neighbor spacing less than about 2 times the size of the particles. [0025]
Another embodiment of the present invention includes a pad conditioner for conditioning resin impregnated fiber pads in which the distance that the abrasive particles protrude from the surface is preferably less than or about equal to the average diameter of the fibers in a resin impregnated fiber pad for which the conditioner will be used. In yet another embodiment, the average nearest neighbor distance between the abrasive particles is less than or equal to the average diameter of the fibers in a resin impregnated fiber pad for which the conditioner will be used. [0026]
In contrast to pad conditioners according to embodiments of the present invention, the standard technology conditioners use larger abrasive particles such as particles having grit less than about 200. In contrast to preferred embodiments of the present invention, the standard technology pad conditioners typically have the particles more widely dispersed, i.e., larger nearest neighbor distances, than for preferred embodiments of the present invention. [0027]
Clearly, the differences in the physical properties between pad conditioners according to embodiments of the present invention and pad conditioners according to the standard technology will result in different conditioning characteristics. The apparatus and methodology of the standard technology for pad conditioning are directed toward making the surface of the pad rougher. Making the pad surface rougher is easily accomplished with the physical properties of the standard technology pad conditioners. [0028]
However, for embodiments of the present invention, it is preferred that the conditioning process and conditioning equipment are used to make the surface of the pad smoother. In other words, one of the functions of pad conditioners and methods of conditioning according to embodiments of the present invention is to substantially maintain a smooth surface for the pad. As a result of maintaining the smooth surface finish, the pad is capable of providing effective planarization efficiency or further improved planarization efficiency. [0029]
The capabilities of embodiments of the present invention are highly advantageous for CMP processes using resin impregnated fiber pads. Preferably, fiber pads capable of providing effective planarization efficiency have a substantially smooth planarizing surface. However, the planarizing process causes the surface of fiber pads to become rougher which reduces the planarization efficiency. The smoothing capabilities of embodiments of the present invention return the planarizing surface of the pad to a substantially smooth surface finish capable of providing effective planarization. [0030]
With this new type of conditioning device and conditioning methods according to embodiments of the present invention, resin impregnated fiber pads such as felt pads can be used for applications that require good planarization or effective planarization, such as dielectric planarization and copper CMP. In other words, some embodiments of the present invention can increase the performance of pads such as fiber pads for applications like CMP and polishing substrates. In some instances, embodiments of the present invention can increase the number of applications for which resin impregnated fiber pads can be used. [0031]
Reference is now made to FIG. 3 where there is shown a side view of another embodiment of a [0032] pad conditioner 30 according to the present invention. Pad conditioner 30 includes a conditioner body 35 and a carrier 40 attached to conditioner body 35. Carrier 40 has a conditioning surface 45. Conditioning surface 45 includes an abrasive surface for abrading the polishing surface of a pad for applications such as chemical mechanical planarization and polishing substrates.
In a preferred embodiment, [0033] carrier 40 serves as a support upon which abrasive particles such as diamond particles are bonded so as to form conditioning surface 45. Carrier 40 may be a flexible material that is attachable to conditioner body 35; conditioner body 35 may serve as a rigid holder. Optionally, conditioner body 35 may include a metal disk and carrier 40 is attached to the surface of the disk. Various attachment methods may be used for attaching carrier 40 to conditioner body 35. Examples of attachment methods are mechanical attachment methods and adhesive attachment methods. Preferred attachment methods are those that allow carrier 40 to be removed and replaced substantially without damaging conditioner body 35.
For the embodiments of the present invention, the particles have a grit greater than about 200. More preferably, the particle grit is greater than about 300 and for some applications greater than 400. Still more preferably, the particles have sizes in the range of the about 1 micrometer to about 50 micrometers. One embodiment uses particles less than about 30 micrometers in size; another embodiment uses particles less than about 15 micrometers in size. [0034] Conditioning surface 45 may have essentially the same abrasive properties as described for conditioning surface 25 for the embodiment described in FIG. 1.
Reference is now made to FIG. 4 where there is shown a side view of elements of an [0035] apparatus 50 for conditioning a pad for applications like chemical mechanical planarization of substrates and polishing substrates. Apparatus 50 is similar to standard apparatus commonly used for applications like chemical mechanical planarization of substrates and polishing substrates with the exception of having a pad conditioner 15 where pad conditioner 15 is essentially the same as that described for FIG. 1. Apparatus 50 also includes a pad support 55. Support 55 is capable supporting a pad during pad conditioning. FIG. 4 shows a pad 60 in order to illustrate the operation of support 55 and conditioner body 20. During conditioning, apparatus 50 causes pad conditioner 15 to contact pad 60 held on support 55. Optionally, support 55 may comprise a turntable for rotating pad 60 during conditioning. It is to be understood that other types of pad support may be used for embodiments of the present invention. Optionally, apparatus 50 may include a pad conditioner like pad conditioner 30 described for the embodiment shown in FIG. 3 instead of pad conditioner 15.
Pad conditioners according to embodiments of the present invention may use abrasive particles typically use for pad conditioning or other abrasive applications. Examples of suitable abrasive particles are diamond particles, aluminum oxide particles, silicon carbide particles, zirconia particles, and boron nitride particles. Optionally, the particles may be anchored with a metal such as nickel. A preferred embodiment of the present invention includes particles of diamond anchored in electroplated nickel pellets. The nickel is bonded to a carrier. [0036]
Another embodiment of the present invention includes an apparatus for conditioning a pad for at least one of chemical mechanical planarization and polishing a substrate. The apparatus comprises a pad conditioner having an abrasive surface. Preferably, the abrasive surface is capable of producing the minimum surface roughness for the pad surface for a size of abrasive particles. Preferably, the abrasive particles are less than 50 micrometers in size. The apparatus also includes a pad support for supporting the pad. The pad conditioner and pad support are coupled so as to allow the pad conditioner to condition the pad. In other words, the apparatus is capable of allowing the pad conditioner to contact the pad to allow conditioning the pad. The pad support of the apparatus may comprise a turntable. Optionally, the pad support may include one or more rollers for a belt pad. [0037]
Descriptions of pad conditioning methods according to embodiments of the present invention will now be presented. One embodiment of the present invention includes a method of conditioning a resin impregnated fiber pad. The method includes the step of abrading the surface of the pad with particles having an average size less than 2 times the average diameter of the fibers. In another embodiment of the present invention, the method includes the step of abrading the surface of the pad with particles having an average size less than 1 times the average diameter of the fibers. [0038]
Some embodiments of the present invention may also include conditioning a resin impregnated fiber pad wherein the step of smoothing the surface of the pad is performed so that the surface finish of the pad after conditioning is smoother than that of the pad before conditioning. In other words, the method involves using the polishing surface of the pad for a process such as CMP and polishing a substrate and having the average roughness of the polishing surface of the pad prior to conditioning higher than the average roughness of the polishing surface of the pad after conditioning. In another embodiment of the present invention, the method of conditioning a resin impregnated fiber pad includes the step of smoothing the surface of the pad with an abrasive comprising abrasive particles supported on a substantially solid surface. For this embodiment, the particles have an average nearest neighbor spacing less than about 4 times the average size of the particles. In addition, the particles have an average size in the range of about 1 micrometer to about 50 micrometers and all ranges subsumed therein. In another embodiment, the particles have an average nearest neighbor spacing less than about 2 times the average size of the particles. In yet another embodiment, the particles have an average nearest neighbor spacing less than about 1 times the size of the particles. [0039]
For some embodiments of the present invention, the step of smoothing the surface comprises abrading the surface with abrasive particles. The particles are bonded to a carrier and the particles are less than 50 micrometers in size. The step of smoothing continues until the surface attains the minimum surface roughness for the particle size. [0040]
The next four examples provide descriptions of examples of the types of pads for which embodiments of the present invention may be used. It is to be understood that the examples given in the present application are merely exemplary of the types of pad for which embodiments of the present invention are applicable. These examples are not intended as limitations of the present invention. In other words, the conditioners and methods of conditioning according to embodiments of the present invention can be used with but are not limited to pads described in the following three examples. [0041]

EXAMPLE 1

Various manufacturing techniques can be used to produce polishing pads for use with embodiments of the present invention. In one embodiment, the polishing pad includes non-woven fibers comprising polyester and a polymer resin comprising polyurethane. Desirable properties for polishing pads according to embodiments of the present invention can be produced using polyester fibers having a denier of about 2. Those skilled in the art know that polishing pads can also be made using other deniers, such as for example, deniers in the range of about 1.5 to about 3.0. [0042]
Desirable properties for the polishing pads can be incorporated into the polishing pads by increasing the ratio of fiber to polymer resin in the polishing pad. For some embodiments, the ratio of polyester fiber to polyurethane resin is in the range of from about 50:50 to about 65:35, and all ratios and ratio ranges subsumed therein. In other words, the polyester makes up from about 50% to about 65% and subranges subsumed therein. The polyurethane resin makes up from about 50% to about 35% and subranges subsumed therein. Preferred embodiments of the pads have ratios of polyester to polyurethane of about 55:45. [0043]
Some starting materials for the pads have a Shore D hardness from about 45 to about 65 and all subranges subsumed therein. A preferred pad has a Shore D hardness from about 47 to about 57 and all subranges subsumed therein. A more preferred pad has a Shore D hardness from about 51 to about 54. [0044]

Table 1 summarizes several physical properties of an example of starting materials for fabricating pads that may be used with embodiments of the present invention. The pads, according to some embodiments, will also have properties like those listed in Table 1 in addition to having a substantially smooth surface for CMP.

TABLE 1


Property	Typical	Preferred

Pad Density gm/cc	0.5-0.7	0.58 +/− 0.04
Fiber to Polymer Resin Ratio	50:50-65:35	55:45
Hardness, Shore D	>47	51-54
Hardness, Shore A		89-98
Felt Density gm/cc		0.32
Pore Size Range um		5-150
Compressibility %		1.8
Resiliency %	70-100	>80

Pads for some embodiments of the present invention were produced by using starting material having properties substantially the same as those described in Table 1. A surface of the starting material was given a surface finish sufficiently smooth to allow effective planarization efficiency. For this particular example, the surface finish was produced by buffing the surface of the starting material with a 30 micrometer grit abrasive belt to remove an amount of material from the surface of the starting material. In this example about 50 micrometers of material was removed from the surface. The surface was also buffed with a 15 micrometer grit abrasive belt to remove an amount of material from the surface of the starting material. In this example, about 50 micrometers of material were removed from the surface. The buffed surface had a smooth surface finish suitable for use for planarizing work pieces. Example applications that the pad was suitable for use in include oxide and shallow trench isolation CMP and for copper metallization CMP. [0046]
The planarization capabilities of pads according to the invention presented in this example have been measured. In addition, similar measurements have been performed for pads having similar properties but without the smooth polishing surface. The experimental results, in general, show that pads according to this example have superior planarization capability over that of the pads without the smooth polishing surface. Specifically, embodiments of the present invention have increased planarization efficiency, decreased erosion, and decreased dishing for CMP processes. One of the pads according to an embodiment of the present invention included a polyester felt impregnated with a polyurethane resin; the pad had a density of about 0.59 grams per cubic centimeter, a compressibility of about 1.8 percent, and a rebound of about 85 percent. The polishing surface of the pad had a surface finish produced by buffing the polishing surface of the pad so that the pad had a sufficient surface finish capable of providing effective planarization efficiency. [0047]

EXAMPLE 2

A method of fabricating a starting material for embodiments of the present invention includes providing a polymer sheet that has a non-woven felt impregnated with a thermoplastic polymer. The sheet has a density less than about 0.7 grams per cubic centimeter, and the sheet has a substrate contacting area. The method further includes the steps of heating the area a sufficient amount and contemporaneously applying a sufficient amount of mechanical pressure so that the density of the sheet increases to greater than about 0.7 grams per cubic centimeter. Polishing pads according to some embodiments of the present invention have densities in the range of from about 0.5 grams per cubic centimeter to about 1.2 grams per cubic centimeter. [0048]
Embodiments of the present invention have been used to produce a pad having a density of about 1.03 grams per cubic centimeter. The pad was made from a starting polymer sheet comprising a non-woven thermoplastic resin impregnated felt having a density of about 0.59 grams per cubic centimeter. During the process, the thickness of the sheet was decreased from an initial thickness of about 0.049 inches (1.24 mm) to a post-process thickness of about 0.027-0.028 inches (0.68-0.71 mm). The thickness decrease produced a substantially corresponding increase in the density of the polymer sheet. The hardness of the polymer sheet also increased. The pad fabricated from the sheet, after the heat and pressure processing, was more dense and harder than the starting polymer sheet. [0049]
In one configuration, a polymer sheet having a nonwoven felt, such as a polyester, impregnated with a thermoplastic resin, such as a polyurethane, was used as a starting polymer sheet. The starting polymer sheet had a Shore D hardness of about 50. The application of sufficient heat and pressure to the starting polymer sheet produced an increase in the hardness of the sheet to a Shore D hardness of about 60-62. [0050]
Some embodiments of the present invention have a Shore D hardness from about 50 to about 65 and all subranges subsumed therein. Preferably for some applications, pads made for embodiments of the present invention have a Shore D hardness of at least about 60. Preferred embodiments have a Shore D hardness from about 60 to about 62 and all subranges subsumed therein. [0051]
For some applications, a preferred starting material is a pad for CMP that includes a polymer composite having a non-woven felt of polymer fibers impregnated with a resin. To produce the pad, the polymer composite is subjected to heat and pressure so that the composite has a density greater than about 0.70 grams per cubic centimeter. In addition, the composite has a Shore D hardness of at least 60. [0052]
As indicated earlier, the process conditions for embodiments of the present invention will be determined in part by properties of the starting polymer sheet. The following example provides process conditions that have been used for fabricating starting materials for embodiments of the present invention. In this example, the polymer sheet includes a nonwoven felt of polymer fibers such as, for example, polyester fibers or nylon fibers. The felt is impregnated with a resin such as, for example, a thermoplastic polyurethane. The polymer sheet has dimensions of about 10.5 inches×10.5 inches and a thickness of about 0.05 inches. The polymer sheet is placed between two substantially smooth steel surfaces. The steel surfaces are heated to about the selected processing temperature. Suitable processing temperatures for this example are in the range of from about 300 degrees F. (149 degree C.) to about 450 degrees F. (232 degree C.), including all temperatures and ranges of temperatures subsumed therein. Preferred temperatures are in the range of about 375 degrees F. (191 degree C.) to about 400 degrees F. (204 degrees C.), including all temperatures and ranges of temperatures subsumed therein. [0053]
Preferably, though it may not be required, the polymer sheet is allowed to contact the heated surfaces for a period of time so that the temperature of the polymer sheet increases to about the temperature for processing. In other words, the sheet may be preheated before application of the high pressure. In this example, the polymer sheet was allowed to heat for about 20 seconds. After heating, pressure was applied to the polymer sheet via the steel surfaces. Suitable pressures for embodiments of the present invention are pressures greater than about 1500 psi (10.3 megapascals). Preferably, the pressures are greater than about 2500 psi (17.2 megapascals). Some particularly good results were obtained using a processing pressure of about 2900 psi (20 megapascals). [0054]
For some of the experiments, a pressure of about 2900 psi (20 megapascals) was applied for a period of about 10 seconds. For other experiments using a pressure of about 2900 psi (20 megapascals), the pressure was applied for a period of about 10 seconds followed by a 180-degree rotation within the plane of the sheet and then followed by another application of pressure at 2900 psi (20 megapascals) for a period of about 10 seconds. The two-step pressure application resulted in greater uniformity of properties of the polymer sheet. It is to be understood that the equipment used for this experiment may not have been optimized for process uniformity and, therefore, should not be considered as a limitation for practicing the present invention. [0055]
Following the application of heat and pressure, the sheet was allowed to cool while sandwiched between two substantially flat plates of aluminum. The plates of aluminum were arranged to provide sufficient pressure to keep the polymer sheet substantially flat during at least part of the cooling step so as to prevent the formation of wrinkles or waves in the surface of the polymer sheet. [0056]
A polymer sheet having a thickness of about 0.050 inches (1.3 mm) was heated to a temperature in the range of about 375 degrees F. (191 degrees C.) to about 400 degrees F. (204 degrees C.). Pressure was applied to the heated polymer sheet until the polymer sheet was compressed to a predetermined thickness fixed by a physical stop having a thickness of about 0.020 inches (0.51 mm). After removal of the pressure and the heat, the polymer sheet had a thickness of about 0.030 inches (0.76 mm). It is to be stood that the starting thickness of the polymer sheet for this example is for purposes of illustration. Other thicknesses can be used for the starting material thickness. [0057]
For the previous example, heated plates were used for carrying out the processing steps. As known by those skilled in the art, an alternative would be to use heated rollers for applying the heat and pressure. In addition, other known techniques for heating and applying pressure can be used in embodiments of the present invention. [0058]
Embodiments of the present invention can be used to produce pads having substantially selectable porosity and density profiles through the thickness of the pad. In other words, by selecting the processing conditions of temperature, pressure, and time duration of their application, the porosity profile near the surface of the pad may differ from that of the profile away from the surface at locations near the middle of the thickness of the pad, i.e., the midpoint of the pad thickness. Optionally, heat may be applied to both sides of the starting polymer sheet or heat may be applied to only one side of the polymer sheet so as to achieve selectable density profiles through the thickness of the pad. [0059]

Table 2 summarizes several physical properties of starting materials for some embodiments of polishing pads according to the present invention. Exemplary pads for use with embodiments of the present invention will also have properties like those listed in TABLE 2 in addition to having a substantially smooth surface for CMP.

TABLE 2


Property	Suitable	Preferred

Pad Density gm/cc	0.5-1.2	about 1
Fiber to Polymer Resin Ratio		55:45
Hardness, Shore D	>about 50	60-62
Felt Density gm/cc		0.32

Pads for use with embodiments of the present invention can be produced by using starting material having properties substantially the same as those described in Table 2. A surface of the starting material can be given a surface finish sufficiently smooth to allow effective planarization or effective planarization efficiency. For this particular example, the surface finish can be produced by buffing the surface of the starting material with a 30 micrometer grit abrasive belt to remove and amount of material from the surface of the starting material. In this example, about 50 micrometers of material may be removed from the surface. The surface can be buffed with a 15 micrometer grit abrasive belt to remove an amount of material from the surface of the starting material. In this example, about 50 micrometers of material may be removed from the surface. The buffed surface is expected to have a smooth surface finish suitable for use for planarizing work pieces and have a higher planarization efficiency than may be possible without the smooth surface according to the present invention. [0061]
Specifically, one embodiment of the present invention is a pad conditioner for pads prepared according to the present disclosure for CMP of a substrate for the purpose of forming at least one of: shallow trench isolation structures, interlayer dielectric structures, intermetal dielectric structures, and copper metallization structures. [0062]

EXAMPLE 3

Various types of pads have been developed in efforts to meet the needs of CMP processes and polishing processes. For a more detailed discussion of representative types of pads see PCT application W 096/15887, the specification of which is incorporated herein by reference. Other representative examples of pads and methods of their fabrication are described in U.S. patents U.S. Pat. No. 4,511,605, U.S. Pat. No. 4,708,891, U.S. Pat. No. 4,728,552, U.S. Pat. No. 4,841,680, U.S. Pat. No. 4,927,432, U.S. Pat. No. 5,533,923, U.S. Pat. No. 6,126,532, U.S. Pat. No. 6,231,434, and U.S. Pat. No. 6,287,185, the specifications of which are also each incorporated herein in their entirety by this reference. Pads according to the present invention can be fabricated using the methods and starting materials described in the previously listed patents and patent applications. The polishing surfaces of those pads can be given a surface finish that can be substantially maintained using the methods disclosed in the present invention so as to produce pads having a higher planarization efficiency than is obtainable without the smooth polishing surface, as described in the present disclosure. [0063]

EXAMPLE 4

Surface Roughness parameters where measured for an example pad suitable for use with an embodiment of the present invention. In other words, the measurements were made for a pad that may be used according to one of the method embodiments of the present invention and with one of the apparatus embodiments of the present invention. The measurements were made according to the DIN 4776 Standard (German Institute for Standardization). [0064]
The following are definitions of measurement parameter notations: [0065]
Rk—Core Roughness Depth—Depth of the roughness core profile. [0066]
Rpk—Reduced peak height—Average height of protruding peaks above the core profile. [0067]
Rvk—Reduced valley depth—Average depth of the profile valleys projecting thorough the roughness core profile. [0068]
Mr1—Material Portion Mr1. [0069]
Mr2—Material Portion Mr2. [0070]
Surface roughness parameters were measured for a pad fabricated according to the method of Example 1, supra. The measurement values for this embodiment of the present invention were Rk from about 2 to about 15, Rpk from about 0.5 to about 5, Rvk from about 8 to about 20, Mr1 from about 1 to about 8, and Mr2 from about 68 to about 78. It is to be understood that the measured parameters are provided merely as an illustration of one example of a pad suitable for use with an embodiment of the present invention. [0071]
While there have been described and illustrated specific embodiments of the invention, it will be clear that variations in the details of the embodiments specifically illustrated and described may be made without departing from the true spirit and scope of the invention as defined in the appended embodiments and their legal equivalents. [0072]
In the foregoing specification, the invention has been described with reference to specific embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present invention. [0073]
Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of any or all the claims. [0074]
As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” “at least one of,” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited only to those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present). [0075]

Claims

What is claimed is:

1. A method of conditioning a pad for at least one of chemical mechanical planarization and polishing a substrate, the method comprising the step of smoothing the surface of the pad so that the surface finish of the pad after conditioning is smoother than that of the pad before conditioning.

2. The method of claim 1 wherein the average roughness of the polishing surface of the pad prior to conditioning is higher than the average roughness of the polishing surface of the pad after conditioning.

3. The method of claim 1 wherein the step of smoothing the surface comprises abrading the surface with abrasive particles less than 50 micrometers in size.

4. The method of claim 1 wherein the step of smoothing the surface comprises abrading the surface with abrasive particles bonded to a carrier and the particles are less than 50 micrometers in size.

5. The method of claim 1 wherein the step of smoothing the surface comprises abrading the surface with abrasive particles bonded to a carrier, the particles are less than 50 micrometers in size, and the particles having an average nearest neighbor spacing less than about 4 times the size of the particles.

6. The method of claim 1 wherein the step of smoothing the surface comprises abrading the surface with abrasive particles, the particles are bonded to a carrier and the particles are less than 50 micrometers in size, the step of smoothing continuing until the surface attains the minimum surface roughness for the particle size.

7. A method of conditioning a resin impregnated fiber pad comprising the step of conditioning the surface of the pad with abrasive particles bonded to a substantially solid surface wherein the particles have an average nearest neighbor spacing less than about 4 times the average size of the particles and the particles having a size of less than 50 micrometers.

8. The method of 7 wherein the particles have an average size less than about 30 micrometers.

9. The method of 7 wherein the particles have an average size less than about 15 micrometers.

10. The method of 7 wherein the particles have a size in the range of about 1 micrometer to less than 50 micrometers.

11. A pad conditioner for conditioning the polishing surface of CMP pads, the conditioner comprising a conditioner body, a carrier, and abrasive particles bonded to a carrier, the carrier being coupled to the conditioner body so as to provide a conditioning surface comprising the particles, and the particles having a grit greater than or equal to about 400.

12. The conditioner of claim 11 wherein the particles comprise at least one of diamond, silicon carbide, aluminum oxide, boron nitride and zirconia.

13. The conditioner of claim 11 wherein the particles comprise diamond.

14. A pad conditioner for at least one of CMP pads and polishing pads, the conditioner comprising abrasive particles bonded to a carrier, the particles having a size less than 50 micrometers and the particles having an average nearest neighbor spacing less than about 4 times the size of the particles.

15. The pad conditioner of claim 14 wherein the particles have an average nearest neighbor spacing less than about 3 times the size of the particles.

16. The pad conditioner of claim 14 wherein the particles have an average nearest neighbor spacing less than about 2 times the size of the particles.

17. An apparatus for conditioning a pad for at least one of chemical mechanical planarization and polishing a substrate, the apparatus comprising:

a pad conditioner comprising an abrasive surface capable of producing the minimum surface roughness for the pad surface for a size of abrasive particles, the abrasive particles being less than 50 micrometers in size, and

a pad support for supporting the pad, the pad conditioner and pad support being coupled so as to allow the pad conditioner to condition the pad.

18. The apparatus of claim 17 wherein the pad support comprises a turntable.

19. The apparatus of claim 17 wherein the pad conditioner comprises abrasive particles between 1 micrometer and 50 micrometers in size.

20. The apparatus of claim 17 wherein the pad conditioner comprises abrasive particles less than about 30 micrometers in size.

21. The apparatus of claim 17 wherein the pad conditioner comprises abrasive particles less than about 15 micrometers in size.

22. The apparatus of claim 17 wherein the pad conditioner comprises abrasive particles bonded to a carrier.

23. The apparatus of claim 22 wherein the pad conditioner comprises abrasive particles selected from the group consisting of silicon carbide particles, aluminum oxide particles, and zirconia particles.

24. The apparatus of claim 22 wherein the pad conditioner comprises diamond particles bonded to a carrier.

25. A method of conditioning a pad for at least one of chemical mechanical planarization and polishing a substrate, the method comprising the step of generating a surface on the pad having a surface roughness less than the minimum surface roughness achievable using abrasive particles less than 50 micrometers in size.

26. A method of conditioning a resin impregnated fiber pad for at least one of chemical mechanical planarization and polishing a substrate comprising the step of abrading the surface of the pad with particles having an average size less than 2 times the average diameter of the fibers.

27. A method of claim 26 wherein the particles have an average size less than 1 times the average diameter of the fibers.