JP2022511763A - Polishing pads and systems, as well as their manufacturing and usage methods - Google Patents

Abstract

The polishing pad includes a polishing layer having a first main surface and a second main surface opposite to the first main surface. The polishing pad further includes a sub-pad having a first main surface and a second main surface opposite the first main surface, which is coupled to the polishing layer. Based on the total surface area of the first main surface of the subpad, at least 50% of the subpad is optically transparent.

Description

The present disclosure relates to polishing pads and systems useful for polishing substrates, as well as methods of manufacturing and using such polishing pads.

In some embodiments, polishing pads are provided. The polishing pad includes a polishing layer having a first main surface and a second main surface opposite the first main surface. The polishing pad further includes a sub-pad having a first main surface and a second main surface opposite the first main surface, coupled to the polishing layer. Based on the total surface area of the first main surface of the subpad, at least 50% of the subpad is optically transparent.

The above summary of the present disclosure is not intended to illustrate each embodiment of the present disclosure. Details of one or more embodiments of the present disclosure are also described below. Other features, objectives and advantages of the present disclosure will become apparent from the specification and the claims.

The following disclosure may be more fully understood by reviewing the detailed description of the various embodiments of the present disclosure in conjunction with the accompanying drawings.
FIG. 3 is a schematic cross-sectional view of a polishing pad according to some embodiments of the present disclosure. FIG. 3 is a schematic diagram of a polishing system according to some embodiments of the present disclosure.

Chemical mechanical flattening (CMP) is a process used to flatten the surface topography of wafers in the manufacture of integrated circuits (ICs) and often employs the use of liquids or slurries and polishing pads. .. During the process, the slurry chemically reacts with the material on the surface of the wafer. The reacted material is then mechanically removed by abrasive particles in the slurry or in the pad. Performance characteristics associated with CMP include wafer removal rate (WRR), wafer non-uniformity (NU), and defects.

With respect to the NU of the wafer, the non-uniformity of the pattern layout within the layers of the IC die often contributes to non-uniform polishing (over-polishing / dishing) over the die region. Fluctuations in CMP process parameters (such as platen and wafer carrier speeds, wafer pressures, slurry transport, etc.), as well as chaotic variations in the process, contribute to increased inhomogeneity within the wafer and lot. In order to reduce variability in polishing results (eg, uniformity, overpolishing, and dishing), we employ integration of in situ measurement and end point detection with process optimization schemes to improve process performance. Using light reflectance, for example, light reflectance that uses a reflected light signal, either single wavelength (ie, a laser source) or broadband light, traveling through the polishing pad to the surface of the wafer. Detecting the end point is one of the known techniques.

The components of a commercially available polishing pad (eg, top pad, sub-pad, optional foam layer, etc.) are typically not optically transparent, for example opaque, with the optical signal generator of the polishing tool. It is placed between the surface of the wafer to be polished. Therefore, these components prevent light measurements that pass directly through the pad. As a result, end point detection windows are often made within the polishing pad to enable optical end point detection. This is suitable within the polishing pad, including the top pad and any optically non-transparent layer to be bonded to the top pad, such as a sub-pad and an optional foam layer that overlaps the polishing pad. It can be achieved by cutting a size opening. The window is then made by inserting a solid, optically transparent (eg, polyurethane) window into the opening and fixing the window to the pad. An end point detection may then be possible by passing an optical signal through a window during the CMP process through a polishing pad, including any of the bonded layers. This practice makes end point detection appropriate, but enabling end point detection through openings in the polishing pad is associated with increased manufacturing complexity of the polishing pad and problems with polishing performance. For example, the formation of an opening through the polishing pad is a further manufacturing process for each layer of the polishing pad. Further, the presence of openings in the polishing pad results in non-uniform pressure on the wafer surface and contact material, and thus performance reliability. Furthermore, since the window of the pad needs to be aligned with the detection system of the tool, for example, the end point detection window of the platen on which the pad is mounted, the end point detection is performed by the end point detection through the opening in the polishing pad. The position of the opening in the resulting pad is limited. As a result, polishing pads that do not require (or minimize the number of openings) openings in the various layers for end point detection will have uniform pressure and contact material on the wafer surface and / or polish. It is desirable because it allows flexibility in the exact location of end point detection through the pad.

Definitions As used herein, the singular forms "a", "an", and "the" include a plurality of referents unless their content is expressly specified otherwise. As used herein and in the accompanying embodiments, the term "or" is generally used to include "and / or" unless the content specifically dictates otherwise.

As used herein, the description of a numerical range by endpoints includes all numbers contained within that range (eg, 1-5 are 1, 1.5, 2, 2.75, 3, 3). .8, including 4 and 5).

Unless otherwise indicated, all numbers representing quantities or components, measured values of properties, etc. used herein and in embodiments are understood to be modified by the term "about" in all cases. It shall be. Accordingly, unless otherwise indicated, the numerical parameters shown in the above specification and the enumeration of the accompanying embodiments will vary depending on the desired characteristics to be obtained by those skilled in the art using the teachings of the present disclosure. Can be. At a minimum, each numerical parameter should be interpreted at least by applying conventional rounding techniques in the light of the number of effective digits reported, which is equivalent to the scope of the claimed embodiment. It does not attempt to limit the application of the theory.

"Working surface" refers to the main surface of the polishing pad that is closest to and at least partially in contact with the main surface of the substrate to be polished.

A "pore" refers to a cavity in the working surface of a pad in which a fluid, such as a liquid, may be contained. The pores allow at least some fluid to be contained within the pores and prevent them from flowing out of the pores.

"Precisely shaped" has a molded shape with an inverted shape of the corresponding mold cavity or mold protrusion, and the shape is maintained after the topographic features are removed from the mold. It means a topographic feature such as a rough surface or pores. The pores formed through the foaming process or the removal of soluble material (eg, water-soluble particles) from the polymer matrix are not precisely formed pores.

As used herein, the "main surface" is the surface of an article or layer that has a larger size or surface area than the other surface of the article or layer, eg, an aspect ratio of a larger width or diameter to height. Refers to the surface of an article or layer having, and the surface area of the sides corresponding to the height (eg, thickness) of the article or layer is significantly smaller than the surface area of the width or diameter of the same article or layer.

As used herein, in some embodiments, "optically transparent" is at least 10% at wavelengths of at least 400 nm when tested as described in the light transmission test methods of the Examples. Refers to an article or layer that has a light transmittance value. In other embodiments, "optically transparent" is at least 20%, at least 30%, at least 40%, at a wavelength of at least 400 nm, when tested as described in the light transmission test method of the Examples. Refers to an article or layer having a light transmittance value of at least 50%, at least 60%, at least 70%, or at least 80%. The term "light transmittance value" is the percentage of light that does not reflect back to the light source or is absorbed by the sample, as a percentage of the total incident light at a wavelength of 400 nm (emission light / light source). It means × 100). For the purposes of this application, an optically transparent article or layer is capable of transmitting the optical signal employed in conventional endpoint detection systems to the extent necessary to achieve accurate endpoint detection. It will be.

When discussing the polishing pad, "thickness" refers to the total average thickness of all layers of the polishing pad measured in the direction perpendicular to the work surface. When discussing layers of polishing pads, "thickness" refers to the total average thickness of such layers of polishing pads measured in the direction perpendicular to the working surface of the polishing pads.

The present disclosure covers articles, systems, and methods useful for polishing substrates, including, for example, semiconductor wafers.

In some embodiments, as shown in FIG. 1, the present disclosure is directed to a polishing pad 10, which can be used, for example, to polish a substrate in a CMP process. The polishing pad 10 has a polishing layer 15 (many) having a first main surface 15A (referred to as a "working surface" of the polishing pad 15) and a second main surface 15B opposite to the first main surface 15A. In the case of, it may include (called an upper pad). The polishing pad 10 further includes a sub-pad 30 coupled to the polishing layer 15, wherein the sub-pad 30 has a first main surface 30A (closest to the polishing layer 15) and a first surface opposite the first main surface 30A. It may have 2 main surfaces 30B (intended to be coupled to the platen of the polishing apparatus). The polishing pad 10 may further include one or more optional layers 40 arranged between the polishing layer 15 and the subpad 30. The layers forming the polishing pad 10 may be bonded to each other by any suitable bonding mechanism known in the art. For example, a pressure sensitive adhesive (PSA), a hot melt adhesive, or an adhesive such as a fixed position curing adhesive may be adopted. Further, or alternative, lamination may be employed.

In some embodiments, the polishing layer 15 may contain or be formed from a polymer. The polishing layer 15 can be made from any known polymer, such as a thermoplastic material, a thermoplastic elastomer (TPE), such as a TPE based on a block copolymer, or a thermosetting material such as an elastomer, and these. Combinations can be mentioned. In some embodiments, the polishing layer may contain, or may be formed from, polyurethane, polyamide, polybutadiene, or polyolefin, such as those common in commercially available polishing pads for substrate flattening. ..

In some embodiments, the hardness of the polishing layer 15 can be controlled primarily by the polymer used to make it. In some embodiments, the hardness of the polishing layer 15 is greater than about 20 shore D, greater than about 30 shore D, or greater than about 40 shore D, less than about 90 shore D, less than about 80 shore D, or about 70 shore D. Less than, 20-90 shore D, 30-80 shore D, or more than 40-70 shore D. In some embodiments, the hardness of the polishing layer 15 is greater than about 20 shore A, greater than about 30 shore A, or greater than about 40 shore A, less than about 95 shore A, less than about 80 shore A, or about 70 shore A. Less than, or 20-95 shore A, 30-80 shore A, or 40-70 shore A.

In some embodiments, the thickness of the polishing layer 15 is greater than about 25 microns, greater than about 50 microns, greater than about 100 microns, or greater than 250 microns, less than about 20 mm, less than about 10 mm, less than about 5 mm, or about 2. It may be less than .5 mm, or 15 microns to 20 mm, 25 microns to 10 mm, 50 microns to 5 mm, or 100 microns to 2.5 mm.

In various embodiments, the polishing layer 15 may be flexible. For example, in some embodiments, it may be possible to bend the polishing layer 15 onto itself, and in the curved region, less than about 10 cm, less than about 5 cm, less than about 3 cm, or less than about 1 cm, and about. A radius of curvature greater than 0.1 mm, greater than about 0.5 mm, or greater than about 1 mm can occur. In some embodiments, it may be possible to bend the polishing layer 15 onto itself, and in the curved region, about 10 cm to about 0.1 mm, about 5 cm to about 0.5 mm, or about 3 cm to about. A radius of curvature of 1 mm can be produced.

In some embodiments, the polishing layer 15 may be a single sheet. For the purposes of this application, a single sheet relates to an article comprising only a single layer of material (ie, neither multi-layered nor bonded), wherein a single layer of material has a single composition. The composition may include a plurality of components, such as a polymer blend or a polymer inorganic complex. The use of a single sheet as a polishing layer can provide cost benefits as it minimizes the number of process steps required to form the polishing layer. Polishing layers, including single sheets, can be made from techniques known in the art, including but not limited to molding and embossing.

In some embodiments, the polishing layer 15 is at least 10%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or, based on the total surface area of the working surface 15a. It may be optically transparent (at least to the extent sufficient to allow end point detection through such a portion of the polishing layer 15) over at least 99%. In such an embodiment, the polishing layer 15 may not include an opening for receiving the end point detection window. In an alternative embodiment, the polishing layer 15 does not have to be optically transparent. In such an embodiment, the polishing layer 15 may include an opening for receiving the end point detection window.

In some embodiments, the polishing layer 15 may include a plurality of precisely molded pores and a plurality of precisely molded rough surfaces on the working surface 15a thereof, eg, US Patent Application No. 1. Some are in the polishing pads described in 15 / 300, 125, the entire contents of which are incorporated herein by reference.

In some embodiments, the subpad 30, or a significant portion of the subpad 30, may include, or may be formed of, an optically transparent material. For example, in some embodiments, the subpad 30 may include, or may be formed from, a soft polymer material having a glass transition below 30 ° C., or a polymer blended with a plasticizer. Other additives such as photoinitiators, free radical initiators, crosslinkers, or inorganic fillers can be added without prejudice to optical transparency.

Suitable soft polymer materials include elastomers, polyurethanes, polyolefins, polycarbonates, polyamides, elastomer rubbers, styrene polymers, polystyrenes, polymethylmethacrylates, copolymers and block copolymers thereof, and mixtures and blends thereof. In some embodiments, the subpad 30 may include, or may be essentially, an oligomer acrylate resin or a methacrylate resin.

Suitable oligomer acrylate monomers include epoxy oligomer acrylate / methacrylate, urethane oligomer acrylate / methacrylate, polyester oligomer acrylate / methacrylate, polyether oligomer acrylate / methacrylate, and amino acrylate / methacrylate monomer.

In some embodiments, suitable monomers have a single ethylenically unsaturated group. The monomer may contain an alkyl (meth) acrylate or may be essentially from an alkyl (meth) acrylate. The alkyl group may be linear, branched, cyclic, bicyclic, tricyclic, adamantyl, or a combination thereof. Suitable alkyl (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and the like. n-pentyl (meth) acrylate, 2-methylbutyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 3,3,5-trimethylcyclohexyl (meth) acrylate, 4-methyl-2-pentyl (Meta) acrylate, 2-ethylhexyl (meth) acrylate, 2-methylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-octyl (meth) acrylate, isononyl (meth) acrylate, Isoamyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, 2-propylheptyl (meth) acrylate, isotridecyl (meth) acrylate, isobornyl (meth) acrylate, isostearyl (meth) acrylate, octadecyl ( Meta) acrylate, 2-octyldecyl (meth) acrylate, dodecyl (meth) acrylate, lauryl (meth) acrylate, dicyclopentenloxyethy (meth) acrylate, dicyclopentenloxyethy (meth) acrylate, 1- Examples thereof include adamantyl (meth) acrylate, 2-adamanti (meth) acrylate, and heptadecanyl (meth) acrylate. Some suitable branched alkyl (meth) acrylates are the (meth) acrylic acids of gelber alcohols with 12-32 carbon atoms described in US Pat. No. 8,137,807 (Clapper et al.). Esther can be mentioned. The alkyl monomer may be a single isomer or an isomer blend such as that described in US Pat. No. 9,102,774 (Clapper et al.). Another monomer with a single ethylenically unsaturated group that can be used is a heteroalkyl (meth) acrylate. The heteroalkyl group may be linear, branched, cyclic, bicyclic, or a combination thereof. Heteroatoms are often oxygen (-O-), but may be sulfur (-S-) or nitrogen (-NH-). Heteroalkyl often have 2-12 carbon atoms and 1-4 heteroatoms, or 4-10 carbon atoms and 1-3 heteroatoms. Suitable heteroalkyl (meth) acrylates include alkoxylated alkyl (meth) acrylates such as 2- (2-ethoxyethoxy) ethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, and 2-ethoxyethyl (meth) acrylate. ) Acrylate can be mentioned. Yet another monomer having a single ethylenically unsaturated group may contain a urethane bond (-NH- (CO) -O-). One example is 2-[[(butylamino) carbonyl] oxy] ethyl acrylate, Rahn USA Corp. It is commercially available from (Aurora, IL, USA) under the trade name GENEMER G1122.

In some embodiments, the suitable plasticizer may be a small molecule, oligomer or polymer compound compatible with the resin / soft polymer system, which will significantly reduce the glass transition temperature of the plastic and more. Become soft. For example, the plasticizer may be sevacate, adipate terephthalate, dibenzoate, glutarate, phthalate, azelate, other ester compounds, or any other such as sulfonamides, organic phosphates, polyethers, and polybutenes compatible with resins. Organic chemicals can be mentioned. Further examples include benzylbutyl phthalate, bis [2- (2-butoxyethoxy) ethyl] adipate, bis (2-ethylhexyl) adipate, bis (2-ethylhexyl) maleate, bis (2-ethylhexyl) sebacate, dibase. Sex ester mixture (mixture of dimethyl adipate and dimethyl glutarate), dibasic ester mixture (mixture of dimethyl glutalate and dimethyl succinate), dimethyl glutarate, dibutyl adipate, dibutylitaconate, dibutyl sebacate, dicyclohexyl Phthalate, diethyl adipate, diethyl azelate, di (ethylene glycol) dibenzoate, diethyl sebacate, diethyl succinate, diheptylphthalate, diisobutyl adipate, diisobutyl fumarate, diisobutyl phthalate, diisodecyl adipate, diisononylphthalate, dimethyl adipate, dimethyl Azelate, dimethylphthalate, di (propylene glycol) dibenzoate, dipropylphthalate, ethyl 4-acetylbutyrate, 2- (2-ethylhexyloxy) ethanol, isooctyltalate, neopentylglycoldimethylsulfate, poly (ethylene glycol) ) Bis (2-ethylhexanoate), poly (ethylene glycol) dibenzoate, poly (ethylene glycol) dioleate, poly (ethylene glycol) monolaurate, poly (ethylene glycol) monooleate, sucrose benzoate, trioctyl lymericate , Trimethyl trimellitate, tri- (2-ethylhexyl) trimellitate, tri- (heptyl, nonyl) trimellitate, N-ethyltoluene sulfoneamide, N- (2-hydroxypropyl) benzenesulfonamide, N- (n-butyl) Examples include benzenesulfonamide. Plasticizers are also bio-based materials, acetylated monoglycerides, triethylcitrate, tributylcitrate, acetyltributylcitrate, trioctylcitrate, acetyltrioctylcitrate, trihexylcitrate, acetyltrihexylcitrate, butyryltri. It may be hexyl citrate, trimethyl citrate, methyl lysinolate, epoxidized soybean oil, or epoxidized vegetable oil.

In some embodiments, the acrylate / methacrylate can be polymerized and crosslinked with a photoinitiator / or heat initiator. In some embodiments, inorganic fillers such as fumed silica, calcium carbonate, kaolin, alumina trihydrate, calcium sulphate, or titanium oxide may be added to alter mechanical performance.

In some embodiments, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 99% of the subpad 30, based on the total surface area of the first main surface 30A of the subpad 30. Alternatively, 100% may be optically transparent. In embodiments where the polishing layer 15 (or at least a portion of the polishing layer 15) is optically transparent, at least 10%, at least 50%, at least 60%, at least 70%, at least the optically transparent region of the subpad 30. 80%, at least 90%, at least 99%, or 100% may overlap the optically transparent region of the polishing layer 15. In such an embodiment, the polishing pad 10 (including the polishing layer 15, the subpad 30, and any intervening layer) is optically transparent (perpendicular to the work surface) at least in the overlapping region of the subpad 30 and the polishing layer 15. In the direction). For the purposes of this application, the overlapping layers of the polishing pad 10 may be directly overlapping layers (ie, physically contacting layers) or indirectly overlapping layers (ie, eg, 1). It is understood that one or more intervening layers can refer to layers that are not in physical contact) but that overlap each other when one layer is superposed on the other. By overlapping the optically transparent regions of the polishing layer 15 and the sub pad 30 in this way, it becomes easy to increase the flexibility of selecting a position in the polishing pad 10 where the end point detection can be performed. In addition, this eliminates the need to include pad windows (and associated openings in the polishing layer and subpads), which allows uniform pressure and contact material from the polishing pad to the substrate to be polished. It will be easier.

In some embodiments, the thickness of the subpad 30 is greater than about 25 microns, greater than about 50 microns, greater than about 100 microns, or greater than 250 microns, less than about 20 mm, less than about 10 mm, less than about 5 mm, or about 2. It may be less than 5 mm, or 25 microns to 20 mm, 50 microns to 10 mm, or 100 microns to 5 mm.

In some embodiments, the subpad 30 may be intended to be sufficiently compatible for the polishing pad 10 to reduce pressure fluctuations on the surface of the substrate to be polished by the polishing pad 10. The pressure non-uniformity is, for example, the fluctuation of the meshing of the slurry polishing particles with the substrate surface due to the fluctuation of the size of the polishing particles, the fluctuation of the thickness in any layer of the polishing pad 10, and the main of the substrate surface and the polishing pad 10. It can be caused by the presence of debris in the contact area between the surface 15A or the topological variation of the substrate surface. Pressure fluctuations on the surface of the substrate exposed to the polishing pad cause unwanted polishing fluctuations on the surface of the substrate and therefore need to be adjusted. In this regard, in some embodiments, the subpad 30 is less than about 4000 kPa, less than about 3000 kPa, or less than about 2000 kPa, more than about 100 kPa, more than about 200 kPa, or more than about 300 kPa, or 4000 kPa to 100 kPa, 3000 kPa to 200 kPa. Alternatively, it may have a Young's modulus of 2000 to 300 kPa. In some embodiments, the subpad 30 may be composed of a material selected according to hardness. In this regard, in some embodiments, the subpad 30 is less than about 70, less than about 60, or more than about 50, more than about 5, more than about 10, or more than about 15, or 70-5, 60-10, Alternatively, it may have a Shore A hardness of 50-15 (measured according to ASTM D2240). In some embodiments, the subpad 30 may be composed of a material selected according to elastic deformation. Elastic deformation can represent the ability of a material to recover to its original state after being deformed. The material of the subpad 30 can be elastically deformable, eg, substantially 100% (eg, 99% or more, 99.5% or more, or 99.9% or more) recoverable to its original state after deformation. possible. In some embodiments, the subpad 30 may be composed of materials selected according to the relax modulus. The relaxed modulus can represent a measure of time-dependent viscoelastic properties. In the present disclosure, the relaxation modulus is measured according to the relaxation test described herein. In this regard, in some embodiments, the subpad 30 may have a relaxation modulus of less than 40%, less than 35%, or less than 30% as measured according to the relaxation test.

In some embodiments, the subpad 30 or at least a portion thereof may include cavities or voids, or may be expanded, carved, or perforated to improve compatibility with the polishing pad 10. The voids and cavities may be scattered and distributed at least in part of the subpad 30, or may be regularly patterned. The volume percentage of the voids and cavities may be less than about 50% by volume, less than about 30% by volume, or less than about 20% by volume, based on the total volume of the subpad 30. The voids may be defects during fabrication, or may be created by different methods such as casting in a mold, mechanical drilling, or laser blasting, but are not limited to these. The voids can have various shapes such as rectangular columns, pyramids, cones, spheres, hemispheres, or others. The voids may pass through the entire subpad layer 30, or may be terminated at the intermediate layer, or may be a combination thereof. The average size of the voids (in terms of longest dimensions) may be less than 5 mm, less than 3 mm, or less than 2 mm. The voids may be arranged in different patterns or densities. In either case, the cavity or void does not effectively interfere with the light transmission of the subpad 30.

In some embodiments, the subpad 30 has less than 1000 kPa, less than 750 kPa, or less than 500 kPa, more than about 25 kPa, more than about 50 kPa, or more than about 75 kPa, or 1000 kPa to 25 kPa, at 25% deflection measured according to ASTM D1056. It may have a compression ratio of 750 kPa to 50 kPa, or 500 to 75 kPa. In some embodiments, the subpad 30 may have a Poisson's ratio of less than 0.5, less than 0.4, less than 0.3, less than about 0.2, or a negative Poisson's ratio.

In some embodiments, the subpad may include multiple layers, eg, two or more layers of material. In some embodiments, the subpad may include a rigid layer, eg, a high modulus material such as a thermoplastic, and a compliant layer, eg, a low modulus material as described above. A polishing pad containing a plurality of subpads having at least one rigid layer and at least one compliant layer makes it possible to adjust the flattening properties of the polishing pad and thus the polishing pad for wafer topography to be polished. It can provide the ability to optimize polishing performance.

In some embodiments, the polishing pad 10 may include one or more layers disposed between the polishing layer 15 and the subpad 30. For example, as shown in FIG. 1, the polishing pad may include a foam layer 40 interposed between the polishing layer 15 and the sub pad 30.

In some embodiments, the foam layer 40 is a suitable list of materials for the foam layer, such as synthetic or natural foams, thermoformed foams, polyurethanes, polyesters, polyethers, filled or grafted poly. It may contain open cells or closed cells containing, or formed of, ether, viscoelastic foam, melamine foam, polyethylene, crosslinked polyethylene, polypropylene, silicone, or ionomer foam.

In some embodiments, the thickness of the foam layer 40 is greater than 25 microns, greater than 50 microns, greater than 100 microns, or greater than 250 microns, less than 20 mm, less than 10 mm, less than 5 mm, or less than 2.5 mm. May be good.

In some embodiments, the foam layer 40 is at least 50%, at least 60%, at least 70%, at least 80%, at least 90% of its surface area, based on the total surface area of one of its main surfaces. Alternatively, it may be optically transparent over at least 99% (at least to the extent sufficient to allow end point detection through such portions of the foam layer 40). In such an embodiment, the foam layer 40 may not include an opening for receiving the end point detection window. In an alternative embodiment, the foam layer 40 does not have to be optically transparent. In such an embodiment, the foam layer 40 may include an opening for receiving the end point detection window.

In some embodiments, the foam layer 40 may have a durometer hardness of about 20 shore D to about 90 shore D and / or about 20 shore A to about 90 shore A.

In some embodiments, in addition to or in place of the foam layer 40, the layer disposed between the polishing layer 15 and the subpad 30 is a polycarbonate, polymethylmethacrylate, polyethylene, polyethylene terephthalate, glycol-modified polyethylene. It may contain one or more rigid polymer layers such as terephthalate, polypropylene, polyvinyl chloride, acrylonitrile-butadiene-styrene. Adhesive layers may also be present, including acrylic adhesives, urethane adhesives, or other epoxy adhesives.

In some embodiments, the thickness of the polishing pad 10 is not particularly limited. For example, the thickness of the polishing pad 10 may match the thickness required to enable polishing with a suitable polishing tool. In some embodiments, the thickness of the polishing pad is greater than 25 microns, greater than 50 microns, greater than 100 microns, or greater than 250 microns, less than 20 mm, less than 10 mm, less than 5 mm, or less than 2.5 mm, or from 25 microns. It may be 20 mm, 50 microns to 10 mm, or 50 microns to 5 mm. The shape of the polishing pad 10 (when viewed from a direction perpendicular to the work surface) is not particularly limited. In some embodiments, the polishing pad 10 may be made such that the pad shape matches the shape of the platen of the corresponding polishing tool to which the pad is attached during use. Pad shapes such as circular, square, and hexagon can be used. The maximum dimension of the directional pad parallel to the work surface (ie, the diameter of the circular pad) is not particularly limited. In some embodiments, such maximum dimensions of the polishing pad 10 are greater than 10 cm, greater than 20 cm, greater than 30 cm, greater than 40 cm, greater than 50 cm, or greater than 60 cm, less than 2.0 m, less than 1.5 m, or 1. It may be less than 0 m.

In some embodiments, the present disclosure relates to a polishing system comprising any one of the polishing pads 10 discussed above and a polishing solution. The polishing solution used is not particularly limited and may be any one known in the art. The polishing solution may be aqueous or non-aqueous. An aqueous polishing solution is defined as a polishing solution having a liquid phase (if the polishing solution is a slurry, it does not contain particles) in which at least 50% by weight is water. A non-aqueous solution is defined as a polishing solution having a liquid phase in which less than 50% by weight is water. In some embodiments, the polishing solution is a slurry, i.e. a liquid containing organic or inorganic abrasive particles, or a combination thereof. The concentration of organic or inorganic abrasive particles or a combination thereof in the polishing solution is not particularly limited. The concentration of organic or inorganic abrasive particles in the polishing solution, or a combination thereof, is greater than 0.5% by weight, greater than 1% by weight, greater than 2% by weight, greater than 3% by weight, greater than 4% by weight, or even more. It may be greater than 5% by weight, less than 30% by weight, less than 20% by weight, less than 15% by weight, or less than 10% by weight. In some embodiments, the polishing solution is substantially free of organic or inorganic abrasive particles. "Substantially free of organic or inorganic abrasive particles" means that the polishing solution is less than 0.5% by weight, less than 0.25% by weight, less than 0.1% by weight of the organic or inorganic abrasive particles. , Or it means that it contains less than 0.05% by weight. In one embodiment, the polishing solution does not have to contain organic or inorganic abrasive particles. The polishing system includes polishing solutions such as slurry used for silicon oxide CMP (including but not limited to shallow trench isolation CMP) and polishing solutions such as slurry used for metal CMP (tungsten CMP, copper CMP, and aluminum). Polishing solutions (including but not limited to tantalum and tantalum nitride CMP) such as slurry used for barrier CMP, and slurry used for polishing hard substrates such as sapphire, including but not limited to CMP. And the like may contain a polishing solution. The polishing system may further include a polished or abraded substrate.

FIG. 2 is a schematic diagram of a polishing system 100 for utilizing polishing pads and methods according to some embodiments of the present disclosure. As shown, the system 100 may include a polishing pad 150 (such as any one of the above polishing pads) and a polishing solution 160. The system may further include a substrate 110 to be polished, a platen 140, and a carrier assembly 130. The adhesive layer 170 can be used to attach the polishing pad 150 to the platen 140 and may be part of the polishing system. The polishing solution 160 may be a layer of solution disposed around the main surface of the polishing pad 150. The polishing solution is typically placed on a working surface in the polishing layer of the polishing pad. The polishing solution may also be present at the interface between the substrate 110 and the polishing pad 150. During the operation of the polishing system 100, the drive assembly 145 may rotate the platen 140 (arrow A) to move the polishing pad 150 to perform the polishing operation. The polishing pad 150 and the polishing solution 160 are used separately or in combination to mechanically and / or chemically remove the material from the main surface of the base material 110 or polish the main surface of the base material 110. The environment can be defined. In order to polish the main surface of the base material 110 with the polishing system 100, the carrier assembly 130 may press the base material 110 against the working surface of the polishing pad 150, that is, the polishing surface in the presence of the polishing solution 160. The platen 140 (and thus the polishing pad 150) and / or the carrier assembly 130 move relative to each other to translate the substrate 110 over the polishing surface of the polishing pad 150. The carrier assembly 130 can rotate (arrow B) and optionally traverse horizontally (arrow C). As a result, the polishing layer of the polishing pad 150 removes the material from the surface of the base material 110. In some embodiments, an inorganic abrasive material, such as an inorganic abrasive particle, may be included in the abrasive layer to facilitate the removal of the material from the surface of the substrate. In other embodiments, the abrasive layer is substantially free of any inorganic abrasive material and the abrasive solution may be substantially free of organic or inorganic abrasive particles, or organic or inorganic abrasive particles. , Or a combination thereof may be contained. The polishing system 100 of FIG. 2 is merely an example of a polishing system that may be employed in connection with the polishing pads and methods of the present disclosure, and other conventional polishing systems may be employed without departing from the scope of the present disclosure. Please understand what you get.

In another embodiment, the present disclosure is a method of polishing a substrate, which comprises preparing a polishing pad with any one of the polishing pads discussed above, preparing the substrate, and preparing the substrate. Bringing the working surface of the polishing pad into contact with the surface of the substrate and moving the polishing pad and the substrate relative to each other while maintaining contact between the working surface of the polishing pad and the surface of the substrate. Including, regarding methods. Such polishing operations can be performed in the presence of a polishing solution. In some embodiments, the polishing solution is a slurry and may include any of the slurries discussed above. In some embodiments, the substrate is a semiconductor wafer. The material forming the surface of the semiconductor wafer to be polished, that is, the material that comes into contact with the working surface of the polishing pad, includes at least one of a dielectric material, a conductive material, a barrier / adhesive material, and a cap material. Not limited to. Examples of the dielectric material include at least one of an inorganic dielectric material such as a silicon oxide film and other glass, and an organic dielectric material. Examples of the metal material include, but are not limited to, at least one of copper, tungsten, aluminum, silver and the like. Examples of the cap material include, but are not limited to, at least one of silicon carbide and silicon nitride. The barrier / adhesive material may include, but is not limited to, at least one of tantalum and tantalum nitride. The method of polishing may also include a pad adjustment or cleaning step, which may be performed in situ, i.e. during polishing. For pad adjustment, use any pad conditioner or brush known in the art, such as the 3.25 inch diameter 3M CMP PAD CONNECTIONER BRUSH PB33A available from 3M Company (St. Paul, Minnesota). Can be used. For cleaning, a 4.25 inch diameter brush such as 3M CMP PAD CONDITIONER BRUSH PB33A available from 3M Company and / or solvent rinse of water or polishing pad may be employed.

Embodiment 1) It is a polishing pad and
A polishing layer having a first main surface and a second main surface opposite to the first main surface,
Includes a subpad having a first main surface and a second main surface opposite the first main surface.
The subpad is bonded to the polishing layer and
A polishing pad in which at least 50% of the subpads are optically transparent, based on the total surface area of the first main surface of the subpads.

2) The polishing pad according to embodiment 1, wherein at least 50% of the polishing layer is optically transparent based on the total surface area of the first main surface of the polishing pad.

3) The polishing pad according to the second embodiment, wherein at least 50% of the optically transparent area of the sub pad overlaps with the optically transparent area of the polishing pad.

4) The polishing pad according to the third embodiment, wherein the polishing pad is optically transparent in a sub-pad region that overlaps with an optically transparent region of the polishing pad.

5) The polishing pad according to any one of embodiments 1 to 4, wherein the sub pad has a Young's modulus of 4000 kPa to 100 kPa, 3000 kPa to 200 kPa, or 300 to 2000 kPa.

6) The polishing pad according to any one of embodiments 1 to 5, wherein the sub pad has a shore A hardness of 5 to 70.

7) The polishing pad according to any one of embodiments 1 to 6, wherein the sub pad is elastically deformable.

8) The polishing pad according to any one of embodiments 1 to 7, wherein the sub pad has a relaxed modulus of less than 40%.

9) The polishing pad according to any one of embodiments 1 to 8, wherein the sub pad contains a cavity or a void.

10) The polishing pad according to embodiment 9, wherein the volume percentage of the voids and cavities is less than about 50.

11) The polishing pad according to any one of embodiments 1 to 10, wherein the sub-pad has a compression rate of 25 to 1000 kPa at a deflection of 25%.

12) The polishing pad according to any one of embodiments 1 to 11, wherein the sub-pad comprises a polymer having a glass transition below room temperature.

13) The polishing pad according to any one of embodiments 1 to 12, wherein the sub-pad contains a polymer and a plasticizer.

14) The polishing pad according to any one of embodiments 1 to 13, wherein the sub-pad contains an acrylate resin or a methacrylate resin.

15) The polishing pad according to any one of embodiments 1 to 14, wherein the polishing layer includes pores and rough surfaces.

16) A method of polishing the base material.
To prepare the polishing pad according to any one of the first to fifteenth embodiments, and to prepare the polishing pad.
Preparing the base material and
Bringing the first main surface of the polishing pad into contact with the substrate,
Moving the polishing pad and the substrate relative to each other while maintaining contact between the first main surface of the polishing pad and the substrate.
Including, how.

Test method:
Glass transition temperature test method The glass transition temperature (Tg, ° C) of the prepared subpad was defined as the position of the peak of the tan δ value as measured from the dynamic mechanical analysis (DMA) test. DMA was performed using the model DMA Q800 available from the dynamic mechanical analyzer, TA Instrument (New Castle, Delaware). Subpad samples 13 mm long and 5.5 mm wide were tested at a scan rate of 5 ° C./min over a temperature range of −60 ° C. to 120 ° C. at a frequency of 1 Hz and in tensile mode. The test results are shown in Table 1.

Light Transmittance Test Method The prepared subpads and the light transmittance of some examples were measured by a tabletop spectrophotometer, X-Rite, Inc. Measurements were made using a model Color i7 from (Grand Rapids, Michigan). Data were collected at 10 nm intervals from 800 nm to 350 nm. The thickness of the sample was about 53 mil (1.34 mm). The test results are shown in Table 2.

Stress Relaxation Test Method The stress relaxation characteristics of the prepared subpads were measured according to ASTM D6048. Cylindrical subpad samples 1.25 inches (3.18 cm) in diameter x 53 mil (1.35 mm) thick were presented in MTS Systems Corp. It was placed in an MTS INSIGHT Electromechanical System manufactured by (Eden Prairie, Minnesota) and held under constant compressive strain (eg, changes in sample thickness divided by its original undeformed thickness). The force applied by the sample to the tester pressure plate was measured and recorded continuously with the corresponding elapsed time. The stress σ, the modulus E (t) at a given time, and the modulus of relaxation (%) were calculated as described below.

The stress (σ) was calculated from the recorded force using the following equation.
σ (t) = force (t) / cross-sectional area of the sample

The elastic modulus (E) was calculated by dividing the stress (σ) by the constant strain (ε _c ) using the following equation.
E (t) = σ (t) / ε _c

The relaxed modulus (%) was calculated using the following equation.
Relaxation elastic modulus (%) = [(E ₀ -E ₂ ) / E ₀ ] ^* 100
In the formula, E ₀ is the instantaneous elastic modulus, and E ₂ is the elastic modulus of the sample material after relaxation for 2 minutes under a constant compressive strain. The instantaneous elastic modulus is defined as the elastic modulus of the sample material immediately after the start of the test. The test results are shown in Table 1.

Compression test method by CMP simulation MTS Systems Corp. A compression cycle test was performed on the subpad sample using the MTS INSIGHT Electromechanical System manufactured by (Eden Prairie, Minnesota). A 1.25 inch (3.18 cm) diameter sample was placed between the 2 inch (51 cm) diameter platen. The sample was then subjected to repeated compression cycles of 60 cycles from 0 psi (0 kPa) to 12 psi (83 kPa) at a frequency of about 1 Hz. After this, it was interrupted for 15 seconds. A series of 60 interruptions at about 1 Hz for 15 seconds were repeated 299 times. A total of 18,000 compression cycles were performed on each sample. The compression values, i.e., the difference in sample thickness when measured at 0 psi and 12 psi, were measured over a time range of 500-700 seconds and then averaged to give the initial compressed value. Similarly, compression values were measured over the last 200 seconds of the test and averaged to give the final compression value. Estimate sample fatigue by comparing the difference between the two means. The test results are shown in Table 1.

Thermal oxide wafer (diameter 300 mm) removal rate test method Regarding the substrate removal rate in the following examples, the thickness of the layer to be polished is determined from the initial (that is, before polishing) thickness and the final (that is, after polishing) thickness. The change in wafer was measured and this difference was calculated by dividing by the polishing time. The thickness measurement was performed by Nova Measurement Instruments Ltd. This is done using the non-contact film analysis system NovaScan3090Next available from (Rehovot, Israel). A 53-point diameter scan with 2 mm edge exclusion was adopted.

Determining Wafer Non-Uniformity For the wafer non-uniformity percentage, calculate the standard deviation of the change in the thickness of the layer to be polished (obtained from the removal rate test method above) at a point on the surface of the wafer. The standard deviation was determined by dividing by the average change in the thickness of the layer to be polished and multiplying the obtained value by 100, so the results were reported as a percentage.

300 mm Thermal Oxide Wafer Polishing Test Method Wafers are used from Applied Materials, Inc. Polishing was performed using a CMP polisher available from (Santa Clara, CA) under the trade name REFLEXION polisher. A 300 mm CONTOUR head for holding a wafer having a diameter of 300 mm was fixed to the grinder. A pad with a diameter of 30.5 inches (77.5 cm) was attached to the platen of the polishing tool with a layer of PSA. There was no break-in procedure. During this polishing, the pressures applied to the zone, zone 1, zone 2, zone 3, zone 4, zone 5, and retaining ring of the CONTOUR head were 3.0 psi (20.7 kPa) and 1.4 psi (9.), respectively. It was 7 kPa), 1.3 psi (9.0 kPa), 1.1 psi (7.6 kPa), 1.1 psi (7.6 kPa), and 3.7 psi (25.5 kPa). The platen speed was 53 rpm and the head speed was 47 rpm. A brush-type pad conditioner, 4.25 inches in diameter, available under the brand name 3M cmp PAD CONDITIONER BRUSH PB33A from 3M Company (St. Paul, Minnesota), mounted on a conditioning arm at a speed of 81 rpm with a downward force of 3 lbf. used. The pad conditioner was swept over the surface of the pad by sine wave sweep for 100% in situ conditioning. The polishing solution was a slurry available under the trade names WIN W7300A34 and WIN W7300B34 from the Cabot Microlectronics Corporation (Aurora, Illinois). Prior to use, WIN W7300A34 and WIN W7300B34 were mixed in a 4: 1 ratio and 30% hydrogen peroxide was added to bring the final volume ratio of A34 + B34 / 30% H ₂ O ₂ to 98/2. .. Polishing was performed at a solution flow rate of 100 mL / min. Fifty thermal oxide monitor wafers were polished for 1 minute and subsequently measured. Thermal oxide monitor wafers with a diameter of 300 mm are available from Advanced Technologies Inc. It was obtained from (Fremont, California). The wafer laminate was as follows. 300 mm basic Si base material + thermal oxide 20KA.

300 mm copper wafer polishing test method by speed monitoring (ISRM) in situ In the copper wafer polishing method, the same 300 mm Reflexion device and brush as for 300 mm thermal oxide wafer polishing were used. During this polishing, the pressure applied to the zone, zone 1, zone 2, zone 3, zone 4, zone 5, and retaining ring of the CONTOUR head was 4.6 psi (31.7 kPa) and 2.2 psi (15.), respectively. It was 2 kPa), 2.1 psi (14.5 kPa), 2.0 psi (13.8 kPa), 2.0 psi (13.8 kPa), and 5.3 psi (36.5 kPa). The polishing procedure was performed using the activated ISRM software. The polishing solution was a slurry available from Planar Solutions LLC (Adrian, Michigan, USA) under the trade name CSL9044c. Prior to use, CSL9044c was diluted with DI water and 30% hydrogen peroxide was added to bring the final volume ratio of 9044c / DI water / _{H2O 2} to 9/88/3. Polishing was performed at a solution flow rate of 150 mL / min. The polishing process was started with 10 dummy thermal oxide wafers followed by Cu wafers. Cu monitor wafers with a diameter of 300 mm are available from Advanced Technologies Inc. It was obtained from (Fremont, California). The wafer laminate was as follows. 300 mm basic Si base material + thermal oxide 3KA + TaN 250A + PVD Cu 1KA + e-Cu 15KA + annealing. The purpose of this test was to observe the ISRM signal for changes when the wafer was completely depleted of Cu, so no Cu thickness measurements were made. ISRM signals were recorded at the times shown in Table 5. Wafers were polished until signal changes were observed and an appropriate amount of overpolishing was completed.

Sub pad 1
97.6 lbs (44.3 kg) CN973H85, 48.0 lbs (21.8 kg) SR-506C, 14.4 lbs (6.53 kg) SR-256, and 0.32 lbs (145 g) Irgure 651 under vacuum. , Mixed at room temperature and degassed. The resulting mixture was cast between two layers of 43543 liner and cured by exposure to UV light at a dose of 2,000 mJ / cm ² . After removal of the liner, the resulting cured film with a width of 38 inches (0.965 m) had a thickness of 53 ± 1 mil (1.34 ± 0.025 mm).

Sub pad 2
106.7 lbs (48.4 kg) CN973H85, 53.3 lbs (24.2 kg) SR-506C, and 0.32 lbs (145 g) Irgacure 651 were mixed and degassed under vacuum at room temperature. The resulting mixture was cast between two layers of 43543 liner and cured by exposure to UV light at a dose of 2,000 mJ / cm ² . After removal of the liner, the resulting cured film with a width of 36 inches (0.914 m) had a thickness of 53 ± 1 mil (1.34 ± 0.025 mm).

Sub pad 3
100 g of CN9071, 120 g of Uniplex 155, and 0.44 g of Irgacure 651 were mixed and degassed under vacuum at room temperature. The resulting mixture was cast between two layers of 43543 liner and cured by exposure to UV light at a dose of 2,500 mJ / cm ² . After removal of the liner, the resulting cured film with a width of 8 inches (20.3 cm) had a thickness of 53 ± 1 mil (1.34 ± 0.025 mm).

Sub pad 4
100 g of CN9021, 40 g of Uniplex 155 and 0.30 g of Irgacure 651 were mixed and degassed under vacuum at room temperature. After removal of the liner, the resulting mixture was cast between the two layers of the 43543 liner and cured by exposure to a dose of 2,500 mJ / cm ² under UV light. The thickness of the obtained cured film having a width of 8 inches (20.3 cm) was 53 ± 1 mil (1.34 ± 0.025 mm).

Sub pad 5
100 lbs (45.4 kg) CN973H85, 40 lbs (18.1 kg) PL-1104, and 0.28 lbs (127 g) Irgacure 651 were mixed and degassed under vacuum at room temperature. The resulting mixture was cast between a layer of PET-EVA film and a layer of 43543 liner and cured by exposure to UV light at a dose of 2,000 mJ / cm ² . The 43543 liner was removed, but the PET-EVA film remained attached to the cured film. The thickness of the obtained cured film having a width of 38 inches (0.965 m) and the PET-EVA film was 58 ± 1 mil (1.47 ± 0.025 mm).

Sub pad 6
The sub-pad 6 is a perforated film having square through holes made from the film of the sub-pad 5. Through-holes can be found in Epilog Corp. Films were made using an Epilog Laser Engraver, model Fusion 40 laser from (Golden, Colorado). The holes are arranged in a square lattice arrangement having a hole width of 1 mm and a hole pitch of 5 mm.

Sub pad 7
The subpad 7 was prepared in the same manner as the subpad 6 except that the pitch of the square grid arrangement was 2.5 mm.

Sub pad 8
The subpad 8 was prepared from the film of the subpad 5. Square blind holes with a depth of 0.1 mm were formed by ablation in the film using the Epilog Laser Engraver. The holes are arranged in an array of square grids having a hole width of 1 mm and a hole pitch of 5 mm.

Sub pad 9
The subpad 9 was prepared in the same manner as the subpad 6 except that the hole width was 2 mm.

Example 1
The polishing pad according to FIG. 1 was prepared by the following procedure. The polishing layer was prepared according to the procedure described in US Pat. No. 6,285,001. More specifically, the polishing layer comprises a plurality of precisely formed rough surfaces and a plurality of precisely formed pores, the rough surface having a carrying area of 24%, height 18 μm, diameter 50 μm,. It was a tapered cylinder with a pitch of 90 μm. The pores had a generally hemispherical shape with a depth of 30 μm, a diameter of 60 μm, and a pitch of 90 μm. Both the plurality of precisely formed rough surfaces and the plurality of precisely formed pores were composed of a square array pattern.

The polymeric material used in the embossing process to form the abrasive layer was thermoplastic polyurethane available from the Lubrizol Corporation (Wickliffe, Ohio) under the trade name Estane58277 resin. The polyurethane had a durometer hardness of about 92 on Shore A and the polishing layer had a thickness of about 22 mil (0.559 mm). During the embossing process, a 2.96 mil (0.0752 mm) PET film was brought into contact with and adhered to the back surface of the polishing layer.

The polishing pad was formed by a plurality of bonding steps using an AGL4400 laminator manufactured by Advanced Greig Laminators, Inc (DeForest, Wisconsin). The first step is a 32 inch pre-bonded subpad (after removal of subpads 1, 43543 liners) with an adhesive available under the brand name 3M ADHESIVE TRANSFER TAPE468MP (from 3M Company, St. Paul, Minnesota). It was to be bonded to a PET sheet of (81 cm) × 32 inches (81 cm) × 10 mil (0.25 mm) on the side to be bonded to the polishing layer. The second step is to bond the rubber-based adhesive to the opposite side of the sub-pad 1, which was used to bond the polishing pad to the platen of the polishing tool during the polishing test. The third step was to bond another layer of 3M ADHESIVE TRANSFER TAPE468MP to the exposed surface of the PET sheet previously bonded to the sub-pad 1 in the first bonding step. The fourth step was to bond the polishing layer to the exposed surface of the 3M ADHESIVE TRANSFER TAPE468MP of the third step, thereby obtaining Example 1. Using prior art, a pad with a diameter of 30.5 inches (76.2 cm) was die-cut to form the final polishing pad.

Example 2
The polishing pad was prepared in the same manner as in Example 1 except that the sub pad 1 was replaced with the sub pad 2, and Example 2 was obtained.

Comparative Example 3
Comparative Example 3 was prepared in the same manner as in Example 1 except that the sub-pad 1 was replaced with a sheet of Poron Foam, and Comparative Example 3 (CE-3) was obtained.

For CE-3, since the transmittance is zero (Table 2), the ISRM signal is expected to be zero, and the use of visible light end point detection is not possible.

Claims (16)

It ’s a polishing pad,
A polishing layer having a first main surface and a second main surface opposite to the first main surface,
Includes a subpad having a first main surface and a second main surface opposite to the first main surface.
The sub-pad is bonded to the polishing layer and
A polishing pad in which at least 50% of the subpads are optically transparent, based on the total surface area of the first main surface of the subpads. The polishing pad according to claim 1, wherein at least 50% of the polishing layer is optically transparent based on the total surface area of the first main surface of the polishing pad. The polishing pad according to claim 2, wherein at least 50% of the optically transparent region of the sub-pad overlaps the optically transparent region of the polishing pad. The polishing pad according to claim 3, wherein the polishing pad is optically transparent in the region of the sub-pad that overlaps the optically transparent region of the polishing pad. The polishing pad according to claim 4, wherein the sub-pad has a Young's modulus of 4000 kPa to 100 kPa, 3000 kPa to 200 kPa, or 300 to 2000 kPa. The polishing pad according to claim 4, wherein the sub-pad has a shore A hardness of 5 to 70. The polishing pad according to claim 4, wherein the sub pad is elastically deformable. The polishing pad according to claim 4, wherein the sub-pad has a relaxed modulus of less than 40%. The polishing pad according to claim 1, wherein the sub-pad contains a cavity or a void. The polishing pad of claim 9, wherein the voids and cavities have a volume percentage of less than about 50. The polishing pad according to claim 4, wherein the sub-pad has a compressibility of 25 to 1000 kPa at a deflection of 25%. The polishing pad according to claim 4, wherein the sub-pad contains a polymer having a glass transition lower than room temperature. The polishing pad according to claim 4, wherein the sub-pad contains a polymer and a plasticizer. The polishing pad according to claim 4, wherein the sub-pad contains an acrylate resin or a methacrylate resin. The polishing pad according to claim 4, wherein the polishing layer includes pores and a rough surface portion. It is a method of polishing the base material.
Preparing the polishing pad according to claim 4 and
Preparing the base material and
Bringing the first main surface of the polishing pad into contact with the base material,
To move the polishing pad and the base material with respect to each other while maintaining contact between the first main surface of the polishing pad and the base material.
Including, how.

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