METHOD FOR PRODUCING CHEMICAL-MECHANICAL POLISHING LAYERS

Abstract

Method for producing a polishing layer for polishing a substrate selected from at least one magnetic substrate, an optical substrate and a semiconductor substrate, comprising: Providing a liquid prepolymer material, Providing a plurality of hollow microspheres, Exposure of a majority of hollow microspheres to a carbon dioxide atmosphere for an exposure period of > 3 hours to form a majority of treated hollow microspheres, Combining the liquid prepolymer material with the majority of treated hollow microspheres to form a curable mixture, Conversion of the curable mixture to form a cured material, commencing ≤ 24 hours after the formation of the majority of treated hollow microspheres, and Separation of at least one polishing layer from the hardened material, wherein the at least one polishing layer has a polishing surface adapted for polishing the substrate.

Description

[0001] The present invention relates generally to the field of producing polishing layers. In particular, the present invention relates to a method for producing polishing layers for use in chemical-mechanical polishing pads.

[0002] In the fabrication of integrated circuits and other electronic devices, multiple layers of conductive, semiconducting, and dielectric materials are deposited onto or removed from the surface of a semiconductor wafer. Thin layers of conductive, semiconducting, and dielectric materials can be deposited using a number of deposition techniques. Common deposition techniques in modern processing include physical vapor deposition (PVD), also known as sputtering; chemical vapor deposition (CVD); plasma-enhanced chemical vapor deposition (PECVD); and electrochemical plating (ECP).

[0003] Because layers of materials are deposited and removed sequentially, the top surface of the wafer becomes non-planar. Since subsequent semiconductor processing (e.g., metallization) requires the wafer to have a flat surface, the wafer must be planarized. Planarization is useful for removing unwanted surface topography and surface defects, such as rough surfaces, agglomerated materials, crystal lattice damage, scratches, and contaminated layers or materials.

[0004] Chemical-mechanical planarization, or chemical-mechanical polishing (CMP), is a common technique used to planarize substrates, such as semiconductor wafers. In conventional CMP, a wafer is mounted on a support structure and placed in contact with a polishing pad within a CMP device. The support structure applies adjustable pressure to the wafer, pressing it against the polishing pad. The pad is moved (e.g., rotated) relative to the wafer by an external drive force. Simultaneously, a chemical composition (a "slurry") or other polishing solution is introduced between the wafer and the polishing pad. Consequently, the wafer surface is polished and made planar by the chemical and mechanical action of the pad surface and the slurry.

[0005] US 5,578,362 A discloses exemplary known polishing coatings. The polishing coatings in US 5,578,362 A comprise a polymeric matrix in which hollow microspheres with a thermoplastic shell are dispersed. Generally, the hollow microspheres are combined and mixed with a liquid polymeric material and transferred into a mold for curing. Traditionally, strict process control is required to facilitate the production of uniform polishing coatings from batch to batch, day to day, and season to season. Furthermore, DE 10,2010,018,012 A1 discloses a method for producing polishing coatings of a chemical-mechanical polishing pad with reduced gas inclusion defects. DE 60,2004,010,871 T2 also describes a polishing wheel.

[0006] Despite the implementation of strict process control, conventional processing techniques still lead to undesirable variations (e.g., pore size and pore distribution) in the resulting polishing layers from batch to batch, day to day, and season to season. Accordingly, there is a continuing need for improved techniques for producing a polishing layer to enhance product uniformity, particularly regarding pore structure.

[0007] The present invention provides a method for producing a polishing layer for polishing a substrate selected from at least one magnetic substrate, an optical substrate, and a semiconductor substrate, comprising: providing a liquid prepolymer material, providing a plurality of hollow microspheres, exposing the plurality of hollow microspheres to a carbon dioxide atmosphere for an exposure period of > 3 hours to form a plurality of treated hollow microspheres, combining the liquid prepolymer material with the plurality of treated hollow microspheres to form a curable mixture, reacting the curable mixture to form a cured material, the reaction commencing ≤ 24 hours after the formation of the plurality of treated hollow microspheres, and separating at least one polishing layer from the cured material.wherein the at least one polishing layer has a polishing surface adapted for polishing the substrate.

[0008] The present invention provides a method for producing a polishing layer for polishing a substrate selected from at least one magnetic substrate, an optical substrate, and a semiconductor substrate, comprising: providing a liquid prepolymer material; providing a plurality of hollow microspheres, each hollow microsphere having an acrylonitrile polymer shell; exposing the plurality of hollow microspheres to a carbon dioxide atmosphere for an exposure period of > 3 hours to form a plurality of treated hollow microspheres; combining the liquid prepolymer material with the plurality of treated hollow microspheres to form a curable mixture; and converting the curable mixture to form a cured material.wherein the reaction is started ≤ 24 hours after the formation of the majority of treated hollow microspheres, and separating at least one polishing layer from the cured material, wherein the at least one polishing layer has a polishing surface adapted for polishing the substrate.

[0009] The present invention provides a method for producing a polishing layer for polishing a substrate selected from at least one magnetic substrate, one optical substrate, and one semiconductor substrate, comprising: providing a liquid prepolymer material, wherein the liquid prepolymer material reacts to form a polyurethane; providing a plurality of hollow microspheres, wherein each hollow microsphere has a vinylidene dichloride-acrylonitrile copolymer shell, the vinylidene dichloride-acrylonitrile copolymer shell encapsulating an isobutane; and exposing the plurality of hollow microspheres to a carbon dioxide atmosphere by fluidizing the plurality of hollow microspheres using a gas for an exposure period of ≥ 5 hours to form a plurality of treated hollow microspheres, wherein the gas is > 30 vol% CO2.Combining the liquid prepolymer material with the plurality of treated hollow microspheres to form a curable mixture, reacting the curable mixture to form a cured material, the reaction commencing ≤ 24 hours after the formation of the plurality of treated hollow microspheres, and separating at least one polishing layer from the cured material, the at least one polishing layer having a polishing surface adapted for polishing the substrate.

[0010] The present invention provides a method for producing a polishing layer for polishing a substrate selected from at least one magnetic substrate, one optical substrate, and one semiconductor substrate, comprising: providing a mold, providing a liquid prepolymer material, providing a plurality of hollow microspheres, exposing the plurality of hollow microspheres to a carbon dioxide atmosphere for an exposure period of > 3 hours to form a plurality of treated hollow microspheres, combining the liquid prepolymer material with the plurality of treated hollow microspheres to form a curable mixture, transferring the curable mixture into the mold, and converting the curable mixture to form a cured material, wherein the conversion is commenced ≤ 24 hours after the formation of the plurality of treated hollow microspheres.wherein the curable mixture reacts in the mold to form the cured material, and separating at least one polishing layer from the cured material, wherein the at least one polishing layer has a polishing surface adapted for polishing the substrate.

[0011] The present invention provides a method for producing a polishing layer for polishing a substrate selected from at least one magnetic substrate, an optical substrate, and a semiconductor substrate, comprising: providing a mold; providing a liquid prepolymer material, wherein the liquid prepolymer material reacts to form a polyurethane; providing a plurality of hollow microspheres, wherein each hollow microsphere has a vinylidene dichloride-acrylonitrile copolymer shell and wherein the vinylidene dichloride-acrylonitrile copolymer shell encapsulates an isobutane; and exposing the plurality of hollow microspheres to a carbon dioxide atmosphere by fluidizing the plurality of hollow microspheres using a gas for an exposure period of ≥ 5 hours to form a plurality of treated hollow microspheres.wherein the gas is ≥ 98 vol% CO2, combining the liquid prepolymer material with the plurality of treated hollow microspheres to form a curable mixture, transferring the curable mixture into the mold, reacting the curable mixture to form a cured material, wherein the reaction is started ≤ 24 hours after the formation of the plurality of treated hollow microspheres, wherein the curable mixture reacts in the mold to form the cured material, and separating at least one polishing layer from the cured material by cutting the cured material to form the at least one polishing layer, wherein the at least one polishing layer has a polishing surface adapted for polishing the substrate. BRIEF DESCRIPTION OF THE DRAWINGS Fig.Figure 1 is a graph of the C90 versus the warm-up temperature curve for a plurality of hollow microspheres treated with nitrogen for an exposure period of eight hours. Fig. Figure 2 is a graph of the C90 versus the warm-up temperature curve for a plurality of hollow microspheres treated with CO2 for an exposure period of three hours. Fig. Figure 3 is a graph of the C90 versus the cooling temperature curve for the majority of hollow microspheres treated with nitrogen for an exposure period of eight hours. Fig. Figure 4 is a graph of the C90 versus the cooling temperature curve for the majority of hollow microspheres treated with CO2 for an exposure period of three hours. Fig.Figure 5 is a graph of the C90 versus the warm-up temperature curve for a plurality of hollow microspheres treated with CO2 for an exposure period of five hours. DETAILED DESCRIPTION

[0012] Surprisingly, it was found that the sensitivity of the pore size in polishing layers to process conditions can be significantly reduced by treating a plurality of hollow microspheres before combining them with a liquid prepolymer material to form a curable mixture from which the polishing layers are formed. In particular, it was found that by treating the plurality of hollow microspheres in the described manner within a batch (e.g., within a mold), from batch to batch, from day to day, and from season to season, wider variations in process temperature can be tolerated while continuously producing polishing layers with a uniform pore size, pore count, and density.Uniformity of pore size and pore count is particularly critical in polishing layers containing a majority of hollow microspheres, where the majority of these hollow microspheres each have a thermally expandable polymer shell. This means that the density of the polishing layer produced with the same loading (i.e., wt.% or number) of hollow microspheres contained in the curable material will vary depending on the actual size (i.e., diameter) of the hollow microspheres after curing of the curable material.

[0013] The term “polyurethane”, as used herein and in the attached claims, comprises (a) polyurethanes formed by the reaction of (i) isocyanates and (ii) polyols (including diols), and (b) polyurethane formed by the reaction of (i) isocyanates with (ii) polyols (including diols) and (iii) water, amines or a combination of water and amines.

[0014] The term "gel point", as used here in reference to a curable mixture, represents the moment in the curing process at which the curable mixture has an infinite shear viscosity in the steady state and an equilibrium modulus of zero.

[0015] The term “mold curing temperature”, as used here, refers to the temperature of the curable mixture during the reaction to form the cured material.

[0016] The term “maximum mold curing temperature”, as used here, refers to the maximum temperature of the curable mixture during the reaction to form the cured material.

[0017] The term "gel time", as used here in reference to a curable mixture, refers to the total curing time for that mixture, which has been determined by means of a standard test procedure in accordance with ASTM D3795-00a (reapproved in 2006) (Standard test procedure relating to the thermal flow, curing and behavior of castable thermosetting materials by a torque rheometer).

[0018] The liquid prepolymer material reacts (i.e., cures) preferably to form a material selected from polyurethane, polysulfone, polyethersulfone, nylon, polyether, polyester, polystyrene, acrylic polymer, polyurea, polyamide, polyvinyl chloride, polyvinyl fluoride, polyethylene, polypropylene, polybutadiene, polyethyleneimine, polyacrylonitrile, polyethylene oxide, polyolefin, polyacrylate, polyalkylacrylate, polymethacrylate, polyalkylmethacrylate, polyetherimide, polyketone, epoxy, silicone, a polymer formed from ethylene propylene diene monomer, protein, polysaccharide, polyacetate, and a combination of at least two of the foregoing. Preferably, the liquid prepolymer material reacts to form a material comprising a polyurethane. More preferably, the liquid prepolymer material reacts to form a material comprising a polyurethane. In particular, the liquid prepolymer material reacts (cures) to form a polyurethane.

[0019] Preferably, the liquid prepolymer material comprises a polyisocyanate-containing material. More preferably, the liquid prepolymer material comprises the reaction product of a polyisocyanate (e.g., diisocyanate) and a hydroxyl-containing material.

[0020] Preferably, the polyisocyanate is composed of methylenebis-4,4'-cyclohexyl isocyanate, cyclohexyl diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, tetramethylene-1,4-diisocyanate, 1,6-hexamethylene diisocyanate, dodecane-1,12-diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, methylcyclohexylene diisocyanate, the triisocyanate of hexamethylene diisocyanate, the triisocyanate of 2,4,4-trimethyl-1,6-hexane diisocyanate, the uretdione of hexamethylene diisocyanate, ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, Dicyclohexylmethane diisocyanate and combinations thereof were selected. In particular, the polyisocyanate is aliphatic and has less than 14 percent unreacted isocyanate groups.

[0021] Preferably, the hydroxyl-containing material used in the present invention is a polyol. Examples of polyols include, for example, polyether polyols, polybutadiene with hydroxyl end groups (including partially and fully hydrogenated derivatives), polyester polyols, polycaprolactone polyols, polycarbonate polyols, and mixtures thereof.

[0022] Preferred polyols include polyether polyols. Examples of polyether polyols include polytetramethylene ether glycol (“PTMEG”), polyethylene propylene glycol, polyoxypropylene glycol, and mixtures thereof. The hydrocarbon chain may contain saturated or unsaturated bonds and substituted or unsubstituted aromatic and cyclic groups. Preferably, the polyol of the present invention comprises PTMEG. Suitable polyester polyols include, among others, polyethylene adipate glycol, polybutylene adipate glycol, polyethylene propylene adipate glycol, o-phthalate-1,6-hexanediol, poly(hexamethylene adipate) glycol, and mixtures thereof. The hydrocarbon chain may contain saturated or unsaturated bonds or substituted or unsubstituted aromatic and cyclic groups.Suitable polycaprolactone polyols include, among others, 1,6-hexanediol-initiated polycaprolactone, diethylene glycol-initiated polycaprolactone, trimethylolpropane-initiated polycaprolactone, neopentyl glycol-initiated polycaprolactone, 1,4-butanediol-initiated polycaprolactone, PTMEG-initiated polycaprolactone, and mixtures thereof. The hydrocarbon chain may contain saturated or unsaturated bonds or substituted or unsubstituted aromatic and cyclic groups. Suitable polycarbonates include, among others, polyphthalate carbonate and poly(hexamethylene carbonate) glycol.

[0023] Preferably, the plurality of hollow microspheres is selected from gas-filled polymeric materials with a hollow core and liquid-filled polymeric materials with a hollow core, wherein the plurality of hollow microspheres each have a thermally expandable polymer shell. Preferably, the thermally expandable polymer shell comprises a material selected from the group consisting of polyvinyl alcohols, pectin, polyvinylpyrrolidone, hydroxyethylcellulose, methylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, hydroxypropylcellulose, polyacrylic acids, polyacrylamides, polyethylene glycols, polyhydroxyetheracrylates, starches, maleic acid copolymers, polyethylene oxide, polyurethanes, cyclodextrin, and combinations thereof.More preferably, the thermally expandable polymer shell comprises an acrylonitrile polymer (where the acrylonitrile polymer is preferably an acrylonitrile copolymer, and more preferably an acrylonitrile copolymer selected from the group consisting of a vinylidene dichloride-acrylonitrile copolymer and an acrylonitrile-alkylacrylonitrile copolymer, wherein the acrylonitrile polymer is particularly a vinylidene dichloride-acrylonitrile copolymer). Preferably, the hollow microspheres are gas-filled polymeric materials with a hollow core, wherein the thermally expandable polymer shell encapsulates a hydrocarbon gas. Preferably, the hydrocarbon gas is selected from the group consisting of at least one of methane, ethane, propane, isobutane, n-butane, isopentane, n-pentane, neopentane, cyclopentane, hexane, isohexane, neohexane, cyclohexane, heptane, isoheptane, octane, and isooctane.More preferably, the hydrocarbon gas is selected from the group consisting of at least one of methane, ethane, propane, isobutane, n-butane, and isopentane. Even more preferably, the hydrocarbon gas is selected from the group consisting of at least one of isobutane and isopentane. In particular, the hydrocarbon gas is isobutane. The hollow microspheres in the plurality of hollow microspheres are, in particular, gas-filled polymeric materials with a hollow core, comprising a copolymer of acrylonitrile and vinylidene chloride as a shell encapsulating an isobutane (e.g., Expancel). ® -Microspheres available from Akzo Nobel).

[0024] The curable mixture comprises a liquid prepolymer material and a plurality of treated hollow microspheres. Preferably, the curable mixture comprises a liquid prepolymer material and a plurality of treated hollow microspheres, wherein the plurality of treated hollow microspheres are uniformly dispersed in the liquid prepolymer material. Preferably, the curable mixture has a maximum mold curing temperature of 72 to 90 °C (more preferably 75 to 85 °C).

[0025] The curable mixture optionally comprises a curing agent. Preferred curing agents include diamines. Suitable polydiamines include both primary and secondary amines. Preferred polydiamines include, but are not limited to, diethyltoluenediamine (“DETDA”), 3,5-dimethylthio-2,4-toluenediamine and isomers thereof, 3,5-diethyltoluene-2,4-diamine and isomers thereof (e.g.,3,5-Diethyltoluene-2,6-diamine), 4,4'-Bis-(sec-butylamino)diphenylmethane, 1,4-Bis-(sec-butylamino)benzene, 4,4'-Methylene-bis-(2-chloroaniline), 4,4'-Methylene-bis-(3-chloro-2,6-diethylaniline) (“MCDEA”), Polytetramethylene oxide di-p-aminobenzoate, N,N'-Dialkyldiaminodiphenylmethane, p,p'-Methylenedianiline (“MDA”), m-Phenylenediamine (“MPDA”), Methylene-bis-2-chloroaniline (“MBOCA”), 4,4'-Methylene-bis-(2-chloroaniline) (“MOCA”), 4,4'-Methylene-bis-(2,6-diethylaniline) (“MDEA”), 4,4'-Methylene-bis-(2,3-dichloroaniline) (“MDCA”), 4,4'-Diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, 2,2',3,3'-Tetrachlorodiaminodiphenylmethane, trimethylene glycol di-p-aminobenzoate, and mixtures thereof. Preferably, the diamine curing agent is selected from 3,5-dimethylthio-2,4-toluenediamine and isomers thereof.

[0026] Curing agents may also include diols, triols, tetraols, and curing agents with terminal hydroxyl groups. Suitable diols, triols, and tetraol groups include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, low molecular weight polytetramethylene ether glycol, 1,3-bis(2-hydroxyethoxy)benzene, 1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene, 1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}benzene, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, resorcinol di-(beta-hydroxyethyl) ether, hydroquinone di-(beta-hydroxyethyl) ether, and mixtures thereof. Preferred curing agents with terminal hydroxyl groups include 1,3-bis(2-hydroxyethoxy)benzene, 1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene, 1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}benzene, 1,4-butanediol, and mixtures thereof. The curing agents with terminal hydroxyl groups and the diamine curing agents may contain one or more saturated, unsaturated, aromatic, and cyclic groups.

[0027] The majority of hollow microspheres are exposed to a carbon dioxide atmosphere for an exposure period of > 3 hours (preferably ≥ 4.5 hours, more preferably ≥ 4.75 hours, in particular ≥ 5 hours) to form a majority of treated hollow microspheres.

[0028] Preferably, the carbon dioxide atmosphere to which the majority of hollow microspheres are exposed for the formation of the majority of treated hollow microspheres comprises ≥ 30 vol% CO2 (more preferably ≥ 33 vol% CO2, even more preferably ≥ 90 vol% CO2, in particular ≥ 98 vol% CO2). Preferably, the carbon dioxide atmosphere is an inert atmosphere. Preferably, the carbon dioxide atmosphere contains < 1 vol% O2 and < 1 vol% H2O. More preferably, the carbon dioxide atmosphere contains < 0.1 vol% O2 and < 0.1 vol% H2O.

[0029] Preferably, a majority of hollow microspheres are exposed to a carbon dioxide atmosphere by fluidizing them using a gas to form a majority of treated hollow microspheres. More preferably, the majority of hollow microspheres are exposed to a carbon dioxide atmosphere by fluidizing them using a gas for an exposure period of > 3 hours (preferably ≥ 4.5 hours, more preferably ≥ 4.75 hours, in particular ≥ 5 hours) to form a majority of treated hollow microspheres, wherein the gas comprises ≥ 30 vol% CO2 (preferably ≥ 33 vol% CO2, more preferably ≥ 90 vol% CO2, in particular ≥ 98 vol% CO2) and wherein the gas contains < 1 vol% O2 and < 1 vol% H2O.In particular, the majority of hollow microspheres are exposed to the carbon dioxide atmosphere by fluidizing the majority of hollow microspheres using a gas for an exposure period of ≥ 5 hours to form the majority of treated hollow microspheres, wherein the gas comprises ≥ 30 vol% CO2 and wherein the gas contains < 0.1 vol% O2 and < 0.1 vol% H2O.

[0030] The majority of treated hollow microspheres are combined with the liquid prepolymer material to form the curable mixture. This curable mixture is then reacted to form a cured material. The reaction to form the cured material begins ≤ 24 hours (preferably ≤ 12 hours, more preferably ≤ 8 hours, particularly ≤ 1 hour) after the formation of the majority of treated hollow microspheres.

[0031] Preferably, the curable material is transferred into a mold, where the curable mixture reacts to form the cured material. Preferably, the mold can be selected from the group consisting of open and closed molds. Preferably, the curable mixture can be transferred into the mold by pouring or injection. Preferably, the mold is equipped with a temperature control system.

[0032] At least one polished layer is separated from the cured material. Preferably, the cured material is a mass from which a plurality of polished layers are separated. Preferably, the mass is cut into a plurality of polished layers of a desired thickness or divided into a plurality of polished layers of a desired thickness in a corresponding manner. More preferably, a plurality of polished layers are separated from the mass by cutting the mass into a plurality of polished layers using a cutting blade. Preferably, the mass is heated to facilitate cutting. More preferably, the mass is heated during cutting to form a plurality of polished layers using an infrared heating source. The at least one polished layer has a polishing surface adapted for polishing the substrate.Preferably, the polishing surface is adapted for polishing the substrate by incorporating a macrotexture selected from at least one of perforations and grooves. Preferably, the perforations from the polishing surface can extend partially or completely through the thickness of the polishing layer. Preferably, the grooves on the polishing surface are arranged such that, when the polishing layer is rotated during polishing, at least one groove moves across the surface of the substrate. Preferably, the grooves are selected from curved grooves, linear grooves, and combinations thereof. The grooves have a depth of ≥ 254 µm (10 mil) (preferably 254 to 3810 µm (10 to 150 mil)).Preferably, the grooves form a groove pattern comprising at least two grooves, each with a combination of a depth selected from ≥ 254 µm (10 mil), ≥ 381 µm (15 mil) and 381 to 3810 µm (15 to 150 mil), a width selected from ≥ 254 µm (10 mil) and 254 to 2540 µm (10 to 100 mil), and a spacing selected from ≥ 762 µm (30 mil), ≥ 1270 µm (50 mil), 1270 to 5080 µm (50 to 200 mil), 1778 to 5080 µm (70 to 200 mil) and 2286 to 5080 µm (90 to 200 mil) is selected.

[0033] Preferably, the method for producing a polishing layer according to the present invention further comprises: providing a mold and transferring the curable mixture into the mold, wherein the curable mixture is reacted in the mold to form the cured material.

[0034] Preferably, the method for producing a polishing layer according to the present invention further comprises: providing a mold, providing a temperature control system, transferring the curable mixture into the mold, wherein the curable mixture is reacted in the mold to form the cured material, and wherein the temperature control system maintains a temperature of the curable mixture while the curable mixture is reacted to form the cured material. More preferably, the temperature control system maintains the temperature of the curable mixture while the curable mixture is reacted to form the cured material, such that a maximum mold curing temperature of the curable mixture during the reaction to form the cured material is 72 to 90 °C.

[0035] An important step in substrate polishing processes is the determination of a polishing endpoint. A common in-situ method for endpoint detection involves directing a light beam onto the substrate surface and analyzing the properties of the substrate surface (e.g., the thickness of any films applied to it) based on the light reflected from the substrate surface to determine the polishing endpoint. To facilitate such light-based endpoint methods, the polishing layers produced by the method of the present invention optionally further include an endpoint detection window. Preferably, the endpoint detection window is an integrated window incorporated into the polishing layer.

[0036] Preferably, the method for producing a polishing layer according to the present invention further comprises: providing a mold, providing a window block, arranging the window block in the mold, and transferring the curable mixture into the mold, wherein the curable mixture is reacted in the mold to form the cured material. The window block may be located in the mold before or after the curable mixture is transferred into the mold. Preferably, the window block is located in the mold before the curable mixture is transferred into the mold.

[0037] Preferably, the method for producing a polishing layer according to the present invention further comprises: providing a mold, providing a window block, providing a window block adhesive, fixing the window block in the mold, and then transferring the curable mixture into the mold, wherein the curable mixture is reacted in the mold to form the cured material. It is assumed that fixing the window block to the mold base reduces the formation of window deformations (e.g., a window that bulges outwards from the polishing layer) when dividing (e.g., cutting) a mass into a plurality of polishing layers.

[0038] Some embodiments of the present invention are described in detail below in the following examples.

[0039] In the following examples, a Mettler RC1 jacketed calorimeter was used, equipped with a temperature control unit, a 1 L jacketed glass reactor, a stirrer, a gas inlet, a gas outlet, a Lasentec probe, and an opening in the reactor sidewall for inserting the end of the Lasentec probe into the reactor. The Lasentec probe was used to investigate the dynamic expansion of the exemplary treated microspheres as a function of temperature. Specifically, with the stirrer running, the setpoint temperature for the calorimeter was increased from 25 °C to 72 °C and then decreased again from 72 °C to 25 °C (as described in the examples), while the size of the exemplary treated microspheres was continuously measured and recorded as a function of temperature using the Lasentec probe (with a focused beam reflection measurement technique).The diameter measurements given in the examples are the C90 chord lengths. The C90 chord length is defined as the chord length for which 90% of the actual chord length measurements yield a smaller value. Comparative examples C1 and C2 and examples 1 to 3

[0040] In each of the comparative examples C1 and C2 and examples 1 to 3, a plurality of hollow microspheres with a shell of a copolymer of acrylonitrile and vinylidene chloride encapsulating isobutane (Expancel) were used. ®DE microspheres (available from Akzo Nobel) were placed on the bottom of the reactor in the RC1 calorimeter. The reactor was sealed, and a purge flow of the gas specified in Table 1 was continuously passed through the reactor for the specified exposure time to form a plurality of treated hollow microspheres. The purge flow was then stopped. The stirrer was then switched on to fluidize the plurality of treated hollow microspheres in the reactor. The setpoint temperature for the RC1 reactor jacket temperature control device was then linearly increased from 25 °C to 82 °C over one hour, while the size of the treated microspheres as a function of temperature was continuously measured and recorded using the Lasentec probe (with a focusing beam reflection measurement technique).The setpoint temperature of the RC1 reactor jacket's temperature control unit was then maintained at 82 °C for thirty (30) minutes before being linearly reduced from 82 °C to 25 °C over the next thirty (30) minutes, during which time the size of the treated microspheres as a function of temperature was continuously measured and recorded using the Lasentec probe (with a focused beam reflection measurement technique). Table 1 Example. gas Suspension period (in hours) C90 against temperature rise after exposure C90 against temperature drop after exposure C1 Nitrogen 8 Fig. 1 Fig. 3 C2 CO2 3 Fig. 2 Fig. 4 1 CO2 5 Fig. 5 -- 2 CO2 8 A -- 3 (CO2 + N2) 8 B -- Mixture of 33% CO2 by volume and 67% nitrogen by volume A The C90 response to the temperature rise of the majority of treated microspheres in Example 2 was consistent with that of the majority of treated microspheres in Example 1. B The C90 response to the temperature rise of the majority of treated microspheres in Example 3 was consistent with that of the majority of treated microspheres in Example 2.

Claims

[1] Method for producing a polishing layer for polishing a substrate selected from at least one magnetic substrate, an optical substrate and a semiconductor substrate, comprising: Providing a liquid prepolymer material, Providing a plurality of hollow microspheres, Exposure of a majority of hollow microspheres to a carbon dioxide atmosphere for an exposure period of > 3 hours to form a majority of treated hollow microspheres, Combining the liquid prepolymer material with the majority of treated hollow microspheres to form a curable mixture, Conversion of the curable mixture to form a cured material, commencing ≤ 24 hours after the formation of the majority of treated hollow microspheres, and Separation of at least one polishing layer from the hardened material, wherein the at least one polishing layer has a polishing surface adapted for polishing the substrate. [2] The method of claim 1, wherein the liquid prepolymer material reacts to form a material selected from the group consisting of polyurethane, polysulfone, polyethersulfone, nylon, polyether, polyester, polystyrene, acrylic polymer, polyurea, polyamide, polyvinyl chloride, polyvinyl fluoride, polyethylene, polypropylene, polybutadiene, polyethyleneimine, polyacrylonitrile, polyethylene oxide, polyolefin, polyacrylate, polyalkylacrylate, polymethacrylate, polyalkylmethacrylate, polyetherimide, polyketone, epoxy, silicone, a polymer formed from ethylene propylene diene monomer, protein, polysaccharide, polyacetate and a combination of at least two of the foregoing. [3] Method according to claim 1, wherein the liquid prepolymer material reacts to form a material comprising a polyurethane. [4] Method according to claim 1, wherein each hollow microsphere in the plurality of hollow microspheres has an acrylonitrile polymer shell. [5] Method according to claim 1, wherein the liquid prepolymer material reacts to form a polyurethane, wherein each hollow microsphere in the plurality of hollow microspheres has a shell of a vinylidene dichloride-acrylonitrile copolymer, wherein the shell, made of a vinylidene dichloride-acrylonitrile copolymer, encapsulates an isobutane, and wherein the majority of hollow microspheres are exposed to the carbon dioxide atmosphere by fluidizing the majority of hollow microspheres using a gas for an exposure period of ≥ 5 hours to form the majority of treated hollow microspheres, wherein the gas is ≥ 30 vol% CO2. [6] The method of claim 1, further comprising: Providing a form and Transferring the curable mixture into the mold, the curable mixture is converted into the hardened material in the mold. [7] Method according to claim 6, further comprising: Cutting the hardened material to form at least one polishing layer. [8] Method according to claim 7, wherein the at least one polishing layer is a plurality of polishing layers. [9] Method according to claim 8, wherein the liquid prepolymer material reacts to form a polyurethane, wherein each hollow microsphere in the plurality of hollow microspheres has a shell of a vinylidene dichloride-acrylonitrile copolymer, wherein the shell, made of a vinylidene dichloride-acrylonitrile copolymer, encapsulates an isobutane, and wherein the majority of hollow microspheres are exposed to the carbon dioxide atmosphere by fluidizing the majority of hollow microspheres using a gas for an exposure period of ≥ 5 hours to form the majority of treated hollow microspheres, wherein the gas is ≥ 30 vol% CO2. [10] Method according to claim 9, wherein the reaction is started ≤ 1 hour after the formation of the plurality of treated hollow microspheres.

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