Chemical mechanical polishing pad

Abstract

A chemical mechanical polishing pad comprising a polishing layer comprising a photocurable polymer wherein the photocurable polymer is a photoinitiated reaction product of a photocurable material that does not contain molecules comprising (meth) acrylate groups, and the photocurable material comprises molecules having two or more functional groups, wherein the functional groups comprise a thiol group and an ethylenically unsaturated group other than a (meth) acrylate group, and the photocuring comprises a reaction of the thiol group with the ethylenically unsaturated group, with the proviso that at least some of the molecules comprise three or more functional groups. The chemical mechanical polishing pad may be prepared by additive manufacturing using stereolithography.

Description

Technical Field

[0001] The present invention relates to a method of forming a polishing pad for chemical mechanical polishing. Background Art

[0002] In the manufacture of integrated circuits and other electronic devices, multiple layers of conductive, semiconductive, and dielectric materials are deposited onto and removed from the surface of a semiconductor wafer. Many deposition techniques can be used to deposit thin layers of conductive, semiconductive, and dielectric materials. Deposition techniques common in modern wafer processing include physical vapor deposition (PVD) (also known as sputtering), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), and electroless plating, among others. Common removal techniques include wet isotropic and anisotropic etching and dry isotropic and anisotropic etching, among others.

[0003] As the material layers are successively deposited and removed, the uppermost surface of the wafer becomes non-planar. Since subsequent semiconductor processing (e.g., metallization) requires the wafer to have a flat surface, planarization of the wafer is needed. Planarization can be used to remove unwanted surface topographies and surface defects such as rough surfaces, agglomerated materials, lattice damage, scratches, and contaminated layers or materials.

[0004] Chemical mechanical planarization, or chemical mechanical polishing (CMP), is a common technique for planarizing or polishing a workpiece such as a semiconductor wafer. In conventional CMP, a wafer carrier or polishing head is mounted on a carrier assembly. The polishing head holds the wafer and positions the wafer in contact with the polishing layer of a polishing pad, which is mounted on a table or platen within a CMP apparatus. The carrier assembly provides a controllable pressure between the wafer and the polishing pad. At the same time, a polishing medium (e.g., slurry) is dispensed onto the polishing pad and drawn into the gap between the wafer and the polishing layer. To perform polishing, the polishing pad and the wafer typically rotate relative to each other. As the polishing pad rotates beneath the wafer, the wafer sweeps out a typically circular polishing track or polishing area where the surface of the wafer directly faces the polishing layer. The wafer surface is polished and made planar by the chemical and mechanical action of the polishing layer and the polishing medium on the surface.

[0005] Additive manufacturing of a polished layer having porosity or a three-dimensional pattern on a polished surface has been proposed. For example, one method uses a microdroplet jetting 3D printing platform. This requires a relatively low-viscosity material that is subsequently photocured. The applied material is then photocured. Examples of photocurable systems suitable for such microdroplet jetting 3D printing can include acrylates, methacrylates, or epoxides as reactive groups for photocuring. See, for example, US2019 / 0224809, US2020 / 0157265, US2021 / 0205951, US11,612,978, and US2019 / 0337117. These chemicals typically undergo chain-growth photocuring. This can result in materials having limited toughness and elongation properties, which may lead to undesirably high wear rates.

[0006] Another method uses photopolymerization (vat polymerization) (including digital light processes, scanning lasers, or stereolithography methods for additive manufacturing). See, for example, US10,350,823. Examples of photocurable systems that can be used in this method include compositions of acrylate-capped isocyanates and acrylate monomers that can be photopolymerized via acrylate or methacrylate groups. See, for example, US2022 / 0119586.

[0007] There is a desire to have chemical mechanical polishing pads that can be produced by additive manufacturing, where these pads have good toughness, elongation, and wear rates (e.g., toughness, elongation, wear rates similar to or better than those of commonly used chemical mechanical polishing pads).

[0008] There is also a desire to have an additive manufacturing process for manufacturing a polished layer for a chemical mechanical polishing pad that enables better toughness, better elongation, wear rates, and greater flexibility in adjusting the mechanical properties of the polished layer. In particular, there is a desire to have a chemical mechanical polishing pad that can be manufactured by additive manufacturing and that has good toughness, good elongation, and good wear rates. SUMMARY OF THE INVENTION

[0009] Disclosed herein is a chemical mechanical polishing pad comprising a photocured polymer, wherein the photocured polymer is a photoinitiated reaction product of a photocurable material that does not contain molecules comprising (meth)acrylate groups, and the photocurable material comprises molecules having two or more functional groups, wherein the functional groups include thiol groups and ethylenically unsaturated groups other than (meth)acrylate groups, and the photocuring comprises the reaction of the thiol groups with the ethylenically unsaturated groups, provided that at least some of these molecules comprise three or more functional groups.

[0010] Also disclosed is the above-mentioned polishing pad, which is formed by a method including the following steps: providing a photocurable material in a container, selectively curing a part of the photocurable material by irradiation to form a cured structure, selectively curing another part of the photocurable material by irradiation to further construct the cured structure, and repeating the selective curing by irradiation until the cured structure has the form of an element of the polishing pad. For example, the element of the polishing pad can be a polishing layer or a sub-layer, or both. Description of the Drawings

[0011] Figure 1 is a schematic diagram of a bottom-up additive manufacturing device as disclosed herein.

[0012] Figure 2 is a schematic diagram of a top-down additive manufacturing device as disclosed herein. Detailed Description

[0013] The disclosed chemical mechanical polishing pad comprises a photocured polymer having good elongation, toughness, and wear rate. The photocuring is accomplished by the reaction of ethylenically unsaturated groups with thiol groups to form thioether (or sulfide) bonds in the polymer. The photocured polymer can form a polishing layer, a sub-layer, or both. The polishing layer or sub-layer thus formed can be free of abrasive particles. The polishing layer can comprise less than 0.1, less than 0.09, less than 0.08, less than 0.07, less than 0.06, less than 0.05, less than 0.04, less than 0.03, less than 0.02, or less than 0.01 volume percent of abrasive particles based on the total volume of the polishing layer.

[0014] The reaction mixture for forming the photocured polymer is suitable for additive manufacturing, including particularly stereolithography or photopolymerization methods. The reaction mixture is free of molecules containing (meth)acrylate groups. As used in this specification, (meth)acrylate includes acrylate, methacrylate, or a mixture containing both acrylate and methacrylate.

[0015] The photocured polymer can be formed by the reaction of a molecule having two or more functional groups, where these functional groups are ethylenically unsaturated groups and thiol groups. For example, a molecule having two or more functional groups can contain both at least one ethylenically unsaturated group and also at least one thiol group. This molecule can be considered an AB-type molecule. As another example, a molecule having two or more functional groups includes a molecule (A) having two or more ethylenically unsaturated groups and a molecule (B) having two or more thiol groups. The AB-type molecule can be used in combination with molecule (A), in combination with molecule (B), or in combination with both molecule (A) and molecule (B). To provide crosslinking, at least a portion of the molecule can have at least three reactive groups (i.e., at least three ethylenically unsaturated groups on the molecule, at least three thiol groups, at least two ethylenically unsaturated groups and one thiol group on the molecule, or at least two thiol groups and one ethylenically unsaturated group on the molecule). The relative amounts of difunctional (i.e., a molecule having two ethylenically unsaturated groups or a molecule having two thiol groups) and higher functional (e.g., a molecule having more than two ethylenically unsaturated groups or a molecule having more than two thiol groups) molecules enable control of the crosslink density.

[0016] Molecule (A) can contain an oligomer (also referred to as a prepolymer), a monomer, or a mixture thereof. Molecule (B) can contain an oligomer (also referred to as a prepolymer), a monomer, or a mixture thereof. By selecting the oligomer and monomer structures and their relative amounts, the properties of the photocured polymer can be adjusted. For example, a rigid polyfunctional olefin used as molecule (A) can provide improved hardness or toughness. When using an oligomer molecule (A), mixing with a monomer molecule (A) can be used for viscosity control while avoiding the use of solvents that may need to be removed after curing.

[0017] The monomer molecule (A) can be, for example, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, diallyl ether, trimethylolpropane diallyl ether, 1,4-butanediol divinyl ether, di(ethylene glycol) divinyl ether, tri(ethylene glycol) divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2,4,6-triallyloxy-1,3,5-triazine, 2,2'-diallylbisphenol A, a polyfunctional acrylamide such as N,N'-methylenebis(acrylamide), or a mixture thereof. These monomer molecules (A) can be used in a mixture with the oligomer molecule (A).

[0018] Advantageously, the polyfunctional isocyanate can react by reacting with a molecule (i.e., a capping agent) containing ethylenic unsaturation and at least one nucleophilic functional group (e.g., amine, hydroxyl, thiol, etc.) to form a urea, carbamate, or thiourea-containing molecule A. Examples of capping agents include allylphenols (e.g., 2-allylphenol, 4-allylphenol, eugenol, isoeugenol), alkylene glycol allyl ethers (e.g., ethylene glycol allyl ether), alkylene glycol mono vinyl ethers (e.g., ethylene glycol mono vinyl ether, butanediol mono vinyl ether), allyl alcohols (e.g., 1-allylcyclohexanol, allyl alcohol, 3-buten-1-ol, 4-penten-1-ol, 2-methyl-3-buten-1-ol, 5-hexen-1-ol), allylamine, 1-allyl-2-thiourea, N-allyl-N'-(2-hydroxyethyl)thiourea, hydroxy norbornene compounds such as 5-norbornene-2-methanol, or mixtures thereof.

[0019] The ethylenic unsaturation in molecule (A) or molecule (AB) can include, for example, vinyl, vinyl ether groups, allyl, allyl ethers, allyl esters, maleimides, norbornene. Allyl, allyl ethers, and allyl esters can provide a good balance of storage stability and photoreactivity. As used herein, allyl means the group -CH 2 -CH=CH 2 . Monosubstituted olefins can provide a rapid reaction with thiol groups, while disubstituted olefins such as crotyl alcohol, trans-3-hexen-1-ol will react at a lower rate. The ethylenic unsaturation is preferably not an acrylate group or an acrylic acid group.

[0020] For example, to prepare molecule (A), the following reaction scheme can be used: R 1 is a linking group. For example, R 1 can include an aliphatic group or an aromatic group or both. For example, R 1 can include a divalent alkyl, cycloalkyl, divalent aryl, divalent aralkyl, or can contain carbon and heteroatoms such as nitrogen. For example, R 1 can be methylene diphenyl, isophorone, 2,4-toluene, 2,6-toluene, hexamethylene, or a uretdione backbone formed by the dimerization of two isocyanate groups. Alternatively, R 1 can be an oligomer group containing 2 or more, 3 or more, up to 150 repeating units. The repeating units can be, for example, alkylene oxides such as ethylene oxide, propylene oxide, or butylene oxide, lactones such as epsilon-caprolactone, saturated and unsaturated forms of hydrocarbon and diene units such as butadiene, isoprene, ethylidene norbornene, dicyclopentadiene, vinyl norbornene, siloxanes such as dimethylsiloxane, and fluorinated units such as vinylidene fluoride and tetrafluoroethylene. R2 is a linking group. For example, R 2 may include an aliphatic group or an aromatic group or both. For example, R 2 may be a divalent alkyl group, a divalent aryl group, a divalent arylalkyl group such as benzyl, phenyl, alkyl, an alicyclic group such as cyclohexyl. R 2 is initially provided with a capping agent having the formula [Y] b -R 2 -[C═C] c The capping agent can generally comprise at least one nucleophile (e.g., OH, NH 2 , or SH) and an ethylenically unsaturated group.

[0021] For example, to form the molecule (A) monomer, a polyisocyanate monomer (e.g., a diisocyanate monomer) can be reacted to form a monomer having at least two ethylenically unsaturated groups. Examples of such polyisocyanate monomers include toluene diisocyanate (TDI) (e.g., 2,4-toluene diisocyanate; 2,6-toluene diisocyanate), diphenylmethane diisocyanate (MDI) (e.g., 4,4'-diphenylmethane diisocyanate); 4,4’-diisocyanatodicyclohexylmethane (H12MDI); naphthalene-1,5-diisocyanate; tolidine diisocyanate; p-phenylene diisocyanate; xylylene diisocyanate; isophorone diisocyanate; hexamethylene diisocyanate; 4,4’-dicyclohexylmethane diisocyanate; cyclohexane diisocyanate; and mixtures thereof.

[0022] As another example, the molecule (A) can include the following oligomers: urethane or urea prepolymers having two or more ethylenically unsaturated groups; polysiloxanes having two or more ethylenically unsaturated groups, such as polydimethylsiloxane; or polyalkylene glycols having two or more ethylenically unsaturated groups. In cases where a urethane or urea chemical composition is desired, such molecule (A) oligomers can be derived from isocyanate prepolymers (such as polyalkylene glycols capped with isocyanate groups or small molecule diisocyanates). Examples of diisocyanates for direct use or as a prepolymer capping end include. The isocyanate-capped urethane prepolymer can have 2 wt% to 30 wt% of unreacted isocyanate (NCO) groups. The prepolymer polyols used to form the polyfunctional isocyanate-capped urethane prepolymer can be selected from the group consisting of: diols, polyols, polyol diols, their copolymers, and mixtures thereof. For example, the prepolymer polyols can be selected from the group consisting of: polyether polyols (e.g., poly(tetramethylene oxide) glycol, poly(propylene oxide) glycol, and mixtures thereof); polycarbonate polyols; polyester polyols; polycaprolactone polyols; mixtures thereof; and mixtures thereof with one or more low molecular weight polyols selected from the group consisting of: ethylene glycol; 1,2-propanediol; 1,3-propanediol; 1,2-butanediol; 1,3-butanediol; 2-methyl-1,3-propanediol; 1,4-butanediol; neopentyl glycol; 1,5-pentanediol; 3-methyl-1,5-pentanediol; 1,6-hexanediol; diethylene glycol; dipropylene glycol; and tripropylene glycol. For example, the prepolymer polyols can be selected from the group consisting of: polytetramethylene ether glycol (PTMEG); ester-based polyols (such as ethylene adipate, butylene adipate); polypropylene ether glycol (PPG); polycaprolactone polyols; their copolymers; and mixtures thereof. For example, the prepolymer polyols can be selected from the group consisting of: PTMEG and PPG. Examples of commercially available PTMEG-based isocyanate-capped urethane prepolymers include prepolymers (available from COIM USA, Inc., such as PET-80A, PET-85A, PET-90A, PET-93A, PET-95A, PET-60D, PET-70D, PET-75D); prepolymers (available from Lanxess, such as LF 800A, LF900A, LF 910A, LF 930A, LF 931A, LF 939A, LF 950A, LF 952A, LF 600D, LF 601D, LF 650D, LF 667, LF 700D, LF750D, LF751D, LF752D, LF753D and L325); Prepolymers (available from Anderson Development Company, such as 70APLF, 80APLF, 85APLF, 90APLF, 95APLF, 60DPLF, 70APLF, 75APLF). Isocyanate-capped urethane prepolymers based on non-TDI can also be used. For example, it is acceptable that the isocyanate-capped urethane prepolymers include those formed by the reaction of 4,4'-diphenylmethane diisocyanate (MDI) with polyols such as polytetramethylene glycol (PTMEG) or diols such as 1,4-butanediol (BDO). Modified MDI products such as polycarbodiimide-modified MDI (e.g., Isonate 143L) and quasi-prepolymers of MDI reacted with low molecular weight diols (e.g., Isonate 181) can be used, and these low molecular weight diols such as 1,2-propanediol; 1,3-propanediol; 1,2-butanediol; 1,3-butanediol; 2-methyl-1,3-propanediol; 1,4-butanediol; neopentyl glycol; 1,5-pentanediol; 3-methyl-1,5-pentanediol; 1,6-hexanediol; diethylene glycol; dipropylene glycol; and tripropylene glycol or combinations thereof. Commercial examples of MDI, polymeric MDI, and MDI prepolymers include ISONATE from Dow Chemical Company TM 143L, ISONATE TM 143LP, ISONATE TM 181, ISONATE TM 240, ISONATE TM M 143, ISONATE TM M320, ISONATE TM M340, ISONATE TM 342, ISOBIND TM 1002, ISOBIND TM 1013, ISOBIND TM 1014, ISOBIND TM 1088, ISOBIND TM 1100, ISOBIND TM 1100S, ISOBIND TM 1200R, PAPI TM 135, PAPI TM 135C, PAPI TM 17, PAPI TM 20, PAPI TM 27, PAPI TM 580N, PAPI TM 6146, PAPITM 901, PAPI TM 94, POLYMERIC MDI 199, POLYMERIC MDI 253, VORANATE TM M 200, VORANATE TM M 220, VORANATE TM 229, VORANATE TM 229N, VORANATE TM M 230, VORANATE TM M 2940, VORANATE TM M 580, VORANATE TM M 595, VORANATE TM M 600, VORANATE TM M 647, VORANATE TM SD 100, VORANATE TM SD 100IF. The prepolymer may contain at least two isocyanate groups. Some commercially available products may include an undisclosed mixture of molecules having two isocyanate groups and molecules having more than two isocyanate groups. An example of a commercial prepolymer believed to have more than two isocyanates per molecule is Desmodur N-3400 from Covestro AG.

[0023] Examples of molecule (B) include but are not limited to alkyl polyfunctional thiols (e.g., 1,2-ethanedithiol, 1,3-propanedithiol, propane-1,2,3-trithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, cyclohexane-1,4-diyldimethanethiol), mercaptopropionates (e.g., ethylene glycol bis(3-mercaptopropionate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), tris[2-(3-mercaptopropionyloxy)ethyl] isocyanurate), thioacetates (e.g., 1,4-butanediol bis(thioacetate)), mercaptoacetates (e.g., pentaerythritol tetrakis(mercaptoacetate)), aromatic dithiols, aralkyls (e.g., aryls having alkylthiol side groups) (e.g., 1,3-benzenedimethanethiol, 1,4-benzenedimethanethiol, 4,4'-bis(mercaptomethyl)biphenyl) and thiol-terminated oligomers (e.g., poly(ethanedithiol) dithiol, poly(dimethylsiloxane) dithiol or urethane or urea oligomers).

[0024] Examples of AB type molecules include allyl mercaptan and oligomers or prepolymers capped with both an ethylenically unsaturated group and a mercaptan group. The oligomers capped with both an ethylenically unsaturated group and a mercaptan group can be prepared as discussed above, but provide a capping group containing ethylenic unsaturation and a capping group having mercaptan functionality.

[0025] The photocured polymer can be formed from a reaction mixture comprising (i) one or more molecules (A) and one or more molecules (B) or (ii) AB type molecules (optionally also having molecule (A), molecule (B) or both). The reaction mixture does not contain molecules containing (meth)acrylate groups.

[0026] The reaction mixture preferably contains a photoinitiator. Exposure to actinic radiation causes the reaction of thiol groups with ethylenically unsaturated groups. For example, the photoinitiator absorbs radiation of an activation wavelength (e.g., ultraviolet radiation having a wavelength of, for example, 200 - 500, 340 - 390 (e.g., 385 nanometers (nm))). For example, the photoinitiator can generate free radicals upon irradiation, and the free radicals initiate the reaction of ethylenically unsaturated groups with thiol groups to form a photocured polymer. Examples of free radical - generating photoinitiators include phenylbis(2,4,6 - trimethylbenzoyl) - phosphine oxide (PPO), diphenyl(2,4,6 - trimethylbenzoyl)phosphine oxide (TPO), 2,2 - dimethoxy - 2 - phenylacetophenone (DMPA), 2 - isopropylthioxanthone (ITX), and benzoyl peroxide. If the ethylenically unsaturated groups are highly reactive, the free radicals can also initiate a side reaction of one ethylenically unsaturated group with another. As another example, the photoinitiator can generate a base upon irradiation, and the base can deprotonate the thiol groups, thereby causing the reaction of thiols with ethylenically unsaturated groups. This method can avoid side reactions between ethylenically unsaturated groups, but due to the adjacent chemical structures on the molecule having ethylenically unsaturated groups, it requires the ethylenically unsaturated groups to be electron - deficient. Examples of electron - deficient alkenes capable of base - catalyzed coupling reactions with thiol groups include, but are not limited to, vinyl silanes, maleimides, and acrylamides. Examples of photo - base generators include 1,2 - dicyclohexyl - 4,4,5,5 - tetramethylbiguanidinium n - butyltriphenylborate (e.g., Fujifilm WPBG - 300), (Z) - {[bis(dimethylamino)methylene]amino} - N - cyclohexyl(cyclohexylamino)methaniminium tetrakis(3 - fluorophenyl)borate (e.g., Fujifilm WPBG - 345) (e.g., 1,2 - diisopropyl - 3 - [bis(dimethylamino)methylene]guanidinium 2 - (3 - benzoylphenyl)propionate (e.g., Fujifilm WPBG - 266), 9 - anthrylmethyl N,N - diethylcarbamate (Fujifilm WPBG - 018). In cases where the photo - base generator does not absorb at the applied wavelength, a photosensitizer such as a thioxanthone substance, or other photo - base generators that absorb at the target wavelength can be used. In cases where the photo - base generator generates free radicals in addition to a base, a free radical inhibitor substance such as 2,2,6,6 - tetramethylpiperidine 1 - oxyl radical (TEMPO) can be used to selectively inhibit free radical side reactions while allowing the base - catalyzed reaction. The amount of the photoinitiator in the reaction mixture can be 0.1, 0.2, 0.3, 0.4, or 0.5 to 5, to 4, to 3, to 2, or to 1.5 wt% based on the total weight of the reaction mixture.

[0027] (For example, the) molar ratio of the ethylenically unsaturated group of molecule (A) to the thiol group of molecule (B) (for example) can be 0.5:1 to 1:0.5, 0.6:1 to 1:0.6, 0.7:1 to 1:0.7, 0.8:1 to 1:0.8, 0.9:1 to 1:0.9, 0.95:1 to 1:0.95, or can be about 1:1.

[0028] In addition to the photoinitiator, the reaction mixture can optionally contain a UV absorber. The UV absorber can be beneficial for adjusting the light penetration of the reaction mixture (i.e., the curing depth). The UV absorber can absorb light at wavelengths (for example, 385 nm) used in additive manufacturing devices. Examples of the UV absorber include 2,2'-dihydroxy-4,4'-dimethoxybenzophenone (DHDMBP) and avobenzone. The amount of the UV absorber can be greater than 0, at least 0.1, at least 0.2, at least 0.3, at least 0.4, or at least 0.5 to 10, to 5, or to 2 wt% based on the total weight of the reaction mixture.

[0029] The reaction mixture can optionally contain a liquid reactive diluent that contains groups (such as ethylenically unsaturated groups or thiols) that react with other components of the reaction mixture. Such a liquid reactive diluent can reduce the viscosity of the reaction mixture to control the viscosity of the reaction mixture. Since the liquid reactive diluent reacts with other components of the reaction mixture, it does not need to be removed after the polishing layer is formed. Such removal may cause shrinkage. Examples of the liquid reactive diluent include liquid allyls, allyl ethers, vinyls, and vinyl ether compounds such as butanediol mono vinyl ether, ethylene glycol vinyl ether, N-vinylpyrrolidone, vinyl acetate, 1-vinylimidazole, 2-vinylpyrazine, vinyl neopentanoate, vinyl propionate, vinyl stearate, vinyl caprate, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, allyl ether, allyl hexanoate, allyl acetate, allyl butyl ether, pentaerythritol allyl ether, allyl methyl carbonate, allyl phenyl ether, allyl heptanoate, allyl butyrate, allyl methyl sulfone, allyl sulfide. Examples can also include liquid thiol compounds such as mercaptopropionic acid, monofunctional mercaptopropionate. The liquid reactive diluent can be present in an amount of 0% to 50%, or 1% to 40%, or 2% to 30%, or 3% to 20%, or 4% to 15%, or 5% to 10% based on the total weight of the reaction mixture.

[0030] The reaction mixture can also contain a non-reactive diluent (such as a solvent, such as dimethyl sulfoxide (DMSO), dimethylformamide (DMF), N-methylpyrrolidone (NMP), acetone, etc.) to reduce the viscosity. However, this may increase the step of solvent removal during the formation of the polishing layer.

[0031] The reaction mixture may also contain non-reactive components that are desired to be included in the polishing layer. These components can increase functionality, such as mechanical reinforcement or porosity. Examples of these components include polymer beads or particles (including expandable polymer microspheres, etc.).

[0032] An example of a reaction scheme for forming a composition that can be used in a polishing pad (e.g., as a polishing layer) is as follows. This reaction scheme shows the main reactions when an ethylenically unsaturated group that is not strongly electron-deficient (e.g., allyl, vinyl, vinyl ether) reacts with a radical-generating photoinitiator where a and b are integers of 2, 3, 4, 5, or 6, provided that at least some of a and b must be 3, 4, 5, or 6 in order to obtain crosslinking, R1 is a polyvalent linking group consistent with the description of molecule (A), and R2 is a polyvalent linking group consistent with the description of molecule (B).

[0033] However, in the case where the ethylenically unsaturated group is electron-deficient (e.g., maleimide or acrylamide), the reaction may include the competitive homopolymerization of the ethylenically unsaturated monomer as follows: where a and b are integers of 2, 3, 4, 5, or 6, provided that at least some of a and b must be 3, 4, 5, or 6 in order to obtain crosslinking, R1 is a polyvalent linking group consistent with the description of molecule (A), and R2 is a polyvalent linking group consistent with the description of molecule (B).

[0034] In the case of using a photo-base generator, the following is a representative reaction scheme:

[0035] where a and b are integers of 2, 3, 4, 5, or 6, provided that at least some of a and b must be 3, 4, 5, or 6 in order to obtain crosslinking, R1 is a polyvalent linking group consistent with the description of molecule (A), and R2 is a polyvalent linking group consistent with the description of molecule (B).

[0036] Examples of specific reaction schemes are:

[0037] The cured polymer that can be used as a polishing layer in a polishing pad as described herein may have a glass transition temperature (T) according to ASTM D5279-21 and selected at the temperature when the maximum tanδ is obtained, such as -20 °C, or -10 °C to 120 °C, to 100 °C, to 70 °C, to 60 °C, or to 50 °C g)。The cured polymers that can be used as the polishing layer in a polishing pad as described herein can have a tensile modulus of, for example, 1, 5, or 10 to 700, to 500, or to 400 megapascals (MPa) according to ASTM D412-05. The cured polymers that can be used as the polishing layer in a polishing pad as described herein can have an elongation at break of, for example, 20%, 50%, 70%, or 100% to 500%, to 450%, to 400%, or to 300% according to ASTM D412. The cured polymers that can be used as the polishing layer in a polishing pad as described herein can have a toughness of, for example, 1, 2, or 5 to 30, or to 20 MPa according to ASTM D412. The cured polymers that can be used as the polishing layer in a polishing pad as described herein can have a cutting rate of, for example, greater than 0 to 2, to 1.5, to 1 millimeter per hour (mm / h) as described herein.

[0038] A method of manufacturing a chemical mechanical polishing pad as disclosed herein is also provided. The method includes providing a photocurable material in a container, selectively curing a portion of the photocurable material by irradiation with radiation of an activation wavelength to form a cured structure, selectively curing an additional portion of the photocurable material by irradiation to further build the cured structure, repeating the selective curing by irradiation until the cured structure has the form of an element of the polishing pad, wherein the photocurable material comprises molecules having two or more functional groups, wherein the functional groups are ethylenically unsaturated groups and thiol groups, provided that the photocurable material does not comprise (meth)acrylate groups and at least some of the molecules comprise three or more functional groups, and wherein the irradiation causes a reaction of the ethylenically unsaturated groups with the thiol groups. The photocurable material in the container can be a liquid. The photocurable material in the container can be flowable under printing conditions. The photocurable material in the container can be spreadable.

[0039] Thus, in one example, as Figure 1As shown, the bottom-up additive manufacturing apparatus includes a container 1. The container 1 has a portion 3 that is transparent to the activating radiation 7. The portion 3 can be located at the bottom of the container 1. The container 1 houses a reaction mixture 10 as described herein (i.e., the reaction mixture comprises a mixture of molecules having two or more functional groups, where the functional groups are ethylenically unsaturated groups and thiol groups, and the reaction is between the ethylenically unsaturated groups and the thiol groups). Such a reaction mixture can be initiated by exposure to radiation. The reaction mixture can include a photoinitiator that generates free radicals upon exposure to radiation of an activating wavelength. The activating radiation 7 passes upwardly through the portion 3 of the container 1 in an imaging manner to cause photocuring of a portion of the reaction mixture 10 at or immediately above the bottom of the container 1. Optionally, a layer 4 can be provided above the surface 3. The layer 4 can prevent the photocured polymer from adhering to the portion 3. The layer 4 can be, for example, a liquid immiscible with the reaction mixture or a low surface energy coating. The layer 4 is also transparent to the activating radiation 7. The first layer 11 of the photocured polymer is formed below the build platform 2. The build platform 2 and the first layer 11 are raised, allowing the reaction mixture 10 to flow beneath the first layer 11. The radiation again passes through the surface 3 in an imaging manner to form a second layer 12 of the photocured polymer. This process is repeated to form additional layers until the desired element (e.g., the polishing layer) of the polishing pad is fully formed.

[0040] In another example as Figure 2 shown, the top-down additive manufacturing apparatus includes a container 1. The container 1 houses a reaction mixture 10 as described herein. A layer of the reaction mixture 10 is disposed above the build platform 2 and exposed to radiation 7 in an imaging manner to form a first layer 11 of the photocured polymer on the build platform 2. The build platform 2 is then lowered, allowing an additional layer of the reaction mixture 10 to cover the first layer 11. A recoating blade 8 can be used to ensure that the reaction mixture 10 completely covers the first layer 11. This is particularly useful for viscous reaction mixtures. The reaction mixture is then again exposed to radiation 7 in an imaging manner to form a second layer 12 of the photocured polymer on the first layer 11. This process is repeated to form additional layers until the desired element (e.g., the polishing layer) of the polishing pad is fully formed.

[0041] The viscosity of the reaction mixture under printing conditions can be from 0.01 Pascal-seconds (Pa-s) to 20 Pa-s, or to 10 Pa-s. The printing conditions can be from room temperature to 200 °C, to 150 °C, to 100 °C, to 80 °C, to 50 °C, but should be below the boiling points and thermal degradation points of the components of the reaction mixture. Room temperature printing conditions can be advantageous for energy efficiency. The reaction mixture can be in liquid form.

[0042] The methods disclosed herein can be used to provide a polished surface having macrotexture (e.g., grooves, ridges, protrusions, depressions), microtexture (e.g., pores, lattice structures, network structures), or both. For example, the grooves can be formed as long or continuous radially concentric depressions from the polished surface. The grooves can have a depth of, for example, 0.1, 0.2, or 0.3 mm to 1.5, to 1.2, or to 1 mm. The grooves can have a width of, for example, 0.05, 0.1, 0.2, or 0.3 to 1, to 0.8, or to 0.6 mm. The protrusions project above the top surface of the base of the polishing pad. The protrusions can be solid or open cylindrical, cubic, pyramidal, or have an irregular cross-section (e.g., leaf-shaped). The protrusions can have a height of 0.05 or 0.1 to 2, or to 1.5 mm. The protrusions can include an opening in the sidewall. The protrusions can include a polished surface that bulges above the top portion of the polishing layer on the support, wherein there is a gap between the polished surface and the top of the base of the polishing pad.

[0043] The chemical mechanical polishing pads disclosed herein can include a sub-pad located on the opposite side of the polished surface of the polishing layer. The polishing layer can be adhered to the sub-pad using an adhesive material after the sub-pad is manufactured. Alternatively, the entire pad can be formed by additive printing, which adjusts the composition of the photosensitive reaction mixture used to form the sub-pad to provide desired properties. The sub-pad material can be more compliant than the polishing layer. The sub-pad can include a porous layer. Alternatively, the sub-pad is an open network of interconnected polymer structures.

[0044] Sub-instances of polymeric materials for one or more sub-layers include: polyurethanes, polycarbonates, polysulfones, nylons, epoxies, polyethers, polyesters, polystyrenes, acrylic polymers, polymethyl methacrylates, polyvinyl chlorides, polyvinyl fluorides, polyethylenes, polypropylenes, polybutadienes, polyethyleneimines, polyethersulfones, polyamides, polyetherimides, polyketones, silicones, their copolymers (such as polyether-polyester copolymers), and combinations or blends thereof. The sub-pad can be formed from a reaction mixture as described herein using thiol-ene curing, which reaction mixture is selected to provide better compliance than that found in the polishing layer. The sub-pad can be formed from a reaction mixture having polymeric precursors (monomers, oligomers, or mixtures thereof) having ethylenically unsaturated groups and thiol groups as described herein. However, the polymeric precursors for the sub-pad are selected to provide better compliance than that found in the polishing layer. If the sub-pad is formed by additive manufacturing, the sub-pad and the polishing layer can be formed sequentially in reaction vessel 1, where the reaction mixture is changed as one moves from one layer to another. For example, the polishing layer can be formed as described above. When forming the polishing layer, reaction mixture 10 can be removed from vessel 1 and a new reaction mixture added. The same exposure process can be carried out to form additional layers on the polishing layer. Alternatively, the sub-pad can be formed first and then the polishing layer can be formed on the sub-pad as a substrate by additive manufacturing. For example, the sub-pad can be formed by additive manufacturing and then the process of forming the polishing layer can be carried out on the sub-pad on the build platform. As another example, a preformed sub-pad can be provided on the build platform and the polishing layer can be formed on the sub-pad by additive manufacturing as described herein.

[0045] A chemical mechanical polishing pad can include a window in the polishing layer. The window is formed from a material that is transparent to the wavelengths used in endpoint detection during the use of the polishing pad. Additive manufacturing can also be used to form a chemical mechanical polishing pad including a window. For example, the polishing layer from the reaction mixture can be formed around window material placed on the build platform. As another example, the polishing layer can be formed with an opening in which the window is later placed. As yet another alternative, the window itself can be formed by additive manufacturing. For example, the window can first be formed by additive manufacturing in vessel 1 of the apparatus and then the polishing layer can be formed around the window by additive manufacturing. As another example, the polishing layer can be formed by additive manufacturing as disclosed herein with a gap for the window and then the window can be formed by additive manufacturing in the gap. The window material can be, for example, polyurethane, acrylic polymer, cycloolefin copolymer (e.g., TOPAS 8007, etc.). In pads where the polishing layer, the sub-layer, or both are also polyurethane, it may be helpful to use polyurethane material. A specific group of examples of aliphatic polyurethanes for the window can be found, for example, in U.S. Patent 10,293,456. Examples

[0046] Prepare a reaction mixture that contains Component 1 - a small molecule (A), which is diallyl phthalate (DAP) or diallyl isophthalate (DAIP); Component 2 - an oligomer molecule. A2a is a PTMEG-based prepolymer capped with TDI and then reacted with allylphenol. A2b is a low molecular weight diol-based prepolymer capped with MDI and then reacted with allylphenol. A2c is a low molecular weight diol-based prepolymer capped with MDI and then reacted with eugenol; Component 3 - a molecule (B) compound having more than 2 thiol functional groups to provide crosslinking, where TMPMP is trimethylolpropane tris(3-mercaptopropionate), and PTMP is pentaerythritol tetra(3-mercaptopropionate); Component 4 - a molecule (B) dithiol functional compound to provide chain extension, where GDMP is ethylene glycol bis(3-mercaptopropionate), and HDT is 1,6-hexanedithiol; and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) as a photoinitiator at 1 wt% based on the total weight of the reaction mixture. The amounts and identities of Components 1-4 are shown in Table 1. The weight percentages are based on the total weight of the reaction mixture. All examples were prepared with a molar ratio of ethylenically unsaturated groups to thiol groups of 1:1. Table 1 Examples 1-7 and the photocurable acrylate composition were cast into films and irradiated under a mercury lamp at 50 mW / cm 2Cure for 5 min on each side. All samples are non-porous and they do not contain any composite fillers such as polymer microspheres or polymer particles. The glass transition temperature (Tg) is according to ASTM D5279-21 and the temperature at the maximum tanδ is selected. The tensile modulus is according to ASTM D412, the elongation at break is according to ASTM D412-05, and the toughness is according to ASTM D412. The cutting rates of the cured acrylates and Examples 1-3 are also tested by the following method: The samples for the wear test are rings with an outer diameter of 7 / 8 inch (2.2 cm) and an inner hole cut diameter of 3 / 8 inch (0.95 cm), thus providing a rim width of 1 / 2 inch (1.3 cm). The samples are punched from pad / plate samples or cured in a PTFE mold of the same size with the above-mentioned Dymax 2000-EC light-curing floodlight system. The samples are loaded on a VEXTA gear head of Vue-More Manufacturing for a sample disk rotating small polishing machine (SSP) and dressed against a Saesol AK45 disk with a diameter of 4.25 inches (10.8 cm) (170 μm diamond, spacing of 315 μm). The dressing disk rotates at 3 rpm (clockwise), and the sample rotates at 300 rpm (counterclockwise) under a down pressure of 1.78 psi (12.3 kPa), which is measured against the rotating diamond dressing disk. These samples are pressed against the dressing disk at the midpoint between the center and the periphery of the dressing disk. These tests are carried out in room temperature DI water without replacement or recycling. Wear data are obtained by removing the samples at time increments of five to thirty minutes and measuring the thickness and a Keyence CL-3000 confocal displacement sensor. Thickness measurements are made at three points, each point spaced 120° around the sample ring and averaged for each time point. These wear results are shown in Table 2. Table 2 Polishing Pad Preparation

[0047] Pour the reaction mixtures of Examples 4-6 separately into a 12-inch (30.5 cm) round mold and cure for 5 minutes on each side with a mercury lamp at an incident intensity of 50 milliwatts per square centimeter (mW / cm 2 ). Then grind the samples to a thickness of 0.080 inch (0.2 cm) and slot them in a circular groove pattern (0.03 inch wide × 0.08 inch pitch - 0.076 × 0.2 cm) using a computer numerical control (CNC) milling machine. Then laminate the samples onto a Suba IV sub-pad from DuPont and punch them into a final diameter of 9 inches (22.9 cm).

[0048] The cast polyurethane samples for polishing evaluation that are not photocured are doctor bladed and cured at 104 °C for 16 h. Then, the cured samples are surface treated, grooved, laminated, and punched in the same manner as the photocured samples. Comparative polyurethane A is characterized by a modulus of 348 MPa and an elongation at break of 298%. Comparative polyurethane B is characterized by a modulus of 183 MPa and an elongation at break of 430%. Polishing Process:

[0049] The polishing tests are completed using a Bruker TriboLab benchtop CMP tool. Before polishing, each pad is run-in (10 minutes) and dressed (10 s, off-tool) with a Saesol AF38 diamond dressing disk under DI water. The TEOS wafers are each polished for 60 seconds at a downforce of 3, 5, and 7 psi (20.7, 34.5, and 48.3 kPa) and a carrier:head speed ratio of 150:151, 225:226, and 300:301 (18 runs per pad in total). For all polishing tests, Klebosol 1730 slurry is used at a flow rate of 100 mL / min. The results are shown in Table 3. Table 3

[0050] The present disclosure further encompasses the following aspects.

[0051] Aspect 1: A chemical mechanical polishing pad comprising a photocured polymer, wherein the photocured polymer is a photoinitiated reaction product of a photocurable material that does not contain molecules comprising (meth)acrylate groups, and the photocurable material comprises molecules having two or more functional groups, wherein the functional groups include thiol groups and ethylenically unsaturated groups other than (meth)acrylate groups, and the photocuring comprises the reaction of the thiol groups with the ethylenically unsaturated groups, provided that at least some of these molecules comprise three or more functional groups.

[0052] Aspect 2: The chemical mechanical polishing pad according to aspect 1, wherein the molecules having two or more functional groups comprise a first molecule having two or more ethylenically unsaturated groups and a second molecule having two or more thiol groups, provided that at least a portion of these first molecules comprises at least three or more ethylenically unsaturated groups or at least a portion of these second molecules comprises three or more thiol groups.

[0053] Aspect 3. The chemical mechanical polishing pad according to aspect 1, wherein these molecules having two or more functional groups include heterotelechelic molecules having ethylenically unsaturated groups and thiol groups.

[0054] Aspect 4. The chemical mechanical polishing pad according to any one of the foregoing aspects, wherein the reaction mixture comprises a photoinitiator that generates free radicals upon exposure to radiation of an activation wavelength.

[0055] Aspect 5. The chemical mechanical polishing pad according to any one of the foregoing aspects, wherein these ethylenically unsaturated groups include allyl groups.

[0056] Aspect 6. The chemical mechanical polishing pad according to aspect 5, wherein the reaction mixture comprises a photoinitiator that generates a base upon exposure to radiation of an activation wavelength.

[0057] Aspect 7. The chemical mechanical polishing pad according to aspect 2, wherein the first molecule comprises a reaction product of a polyisocyanate and an ethylenically unsaturated capping agent, and the polyisocyanate comprises an oligomer, a polyfunctional isocyanate monomer, or a mixture thereof.

[0058] Aspect 8. The chemical mechanical polishing pad according to aspect 2, wherein the first molecule includes an oligomer comprising two or more ethylenically unsaturated groups and a monomer comprising two or more ethylenically unsaturated groups, and the second molecule includes one or more of an alkyl polyfunctional thiol, an aromatic polyfunctional thiol, a polyfunctional mercaptopropionate, a polyfunctional thioethanolate, a polyfunctional mercaptoacetate, and a thiol-capped oligomer having two or more thiol groups.

[0059] Aspect 9. The chemical mechanical polishing pad according to any one of the foregoing aspects, which comprises abrasive particles in an amount less than 0.05 weight percent based on the total weight of the polishing pad.

[0060] Aspect 10. The polishing pad according to any one of the foregoing aspects, the polishing pad being formed by a method comprising: providing the photocurable material in a container, selectively curing a portion of the photocurable material by irradiation to form a cured structure, selectively curing an additional portion of the photocurable material by irradiation to further build the cured structure, repeating the selective curing by irradiation until the cured structure has the form of the polishing layer of the polishing pad.

[0061] Aspect 11. The polishing pad according to aspect 10, wherein the photocurable material provided comprises: i) a monomer or oligomer or a mixture thereof having two or more ethylenically unsaturated groups, and ii) a monomer or oligomer having two or more thiol groups or a mixture thereof.

[0062] All ranges disclosed herein include the endpoints, and the endpoints can be combined independently of each other (e.g., a range of "up to 25 wt.%, or more specifically 5 wt.% to 20 wt.%" includes the endpoints and all intermediate values within the range of "5 wt.% to 25 wt.%", etc.). In addition, the upper and lower limits can be combined to form a range (e.g., "at least 1 or at least 2 weight percentages" and "up to 10 or 5 weight percentages" can be combined into a range of "1 to 10 weight percentages", or "1 to 5 weight percentages", or "2 to 10 weight percentages", or "2 to 5 weight percentages").

[0063] The present disclosure may alternatively include any suitable components disclosed herein, consist of any suitable components disclosed herein, or consist essentially of any suitable components disclosed herein. The present disclosure may additionally or alternatively be formulated so as to be free of, or substantially free of, any components, materials, ingredients, adjuvants or substances used in prior art compositions or otherwise not necessary to achieve the functions and / or objectives of the present disclosure.

[0064] All cited patents, patent applications and other references are incorporated herein by reference in their entirety. However, if the terms in the present application conflict or contradict the terms in the incorporated references, then the terms from the present application shall prevail over the conflicting terms from the incorporated references.

[0065] Unless stated to the contrary herein, all test standards are the latest standards effective as of the filing date of the present application or, if priority is claimed, as of the filing date of the earliest priority application in which the test standard appears.

Claims

1. A chemical mechanical polishing pad comprising a photocured polymer, wherein the photocured polymer is a photoinitiated reaction product of a photocurable material that does not contain molecules containing (meth)acrylate groups, and the photocurable material contains molecules having two or more functional groups, wherein the functional groups include thiol groups and ethylenically unsaturated groups other than (meth)acrylate groups, and the photocuring includes a reaction of the thiol groups with the ethylenically unsaturated groups, provided that at least some of the molecules contain three or more functional groups.

2. The chemical mechanical polishing pad according to claim 1, wherein The molecules having two or more functional groups include first molecules having two or more ethylenically unsaturated groups and second molecules having two or more thiol groups, provided that at least a portion of the first molecules include at least three or more ethylenically unsaturated groups or at least a portion of the second molecules include three or more thiol groups.

3. The chemical mechanical polishing pad according to claim 1, wherein: The molecules having two or more functional groups include isotelechelic molecules having an ethylenically unsaturated group and a thiol group.

4. The chemical mechanical polishing pad according to claim 1, wherein: The reaction mixture includes a photoinitiator that generates free radicals when exposed to radiation of an activating wavelength.

5. The chemical mechanical polishing pad according to claim 4, wherein: The ethylenically unsaturated group includes an allyl group.

6. The chemical mechanical polishing pad according to claim 1, wherein: The reaction mixture comprises a photoinitiator that generates a base when exposed to radiation of an activating wavelength.

7. The chemical mechanical polishing pad according to claim 2, wherein: The first molecule comprises the reaction product of a polyisocyanate comprising an oligomer, a polyfunctional isocyanate monomer, or a mixture thereof and an ethylenically unsaturated capping agent.

8. The chemical mechanical polishing pad according to claim 2, wherein: The first molecule includes an oligomer including two or more ethylenically unsaturated groups and a monomer including two or more ethylenically unsaturated groups, and the second molecule includes one or more of an alkyl multifunctional thiol, an aromatic multifunctional thiol, a multifunctional mercaptopropionate, a multifunctional thioglycolate, a multifunctional thioglycolate, a thiol-terminated oligomer having two or more thiol groups.

9. The polishing pad of claim 1, wherein the polishing pad is formed by a method comprising: The photocurable material is provided in a container, a portion of the photocurable material is selectively cured by irradiation to form a cured structure, another portion of the photocurable material is selectively cured by irradiation to further build up the cured structure, and the selective curing by irradiation is repeated until the cured structure has the form of the polishing layer of the polishing pad.

10. The polishing pad according to claim 9, wherein: The photocurable material provided includes the following items: i) a monomer or oligomer having two or more ethylenically unsaturated groups or a mixture thereof, and ii) a monomer or oligomer having two or more thiol groups or a mixture thereof.

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