Chemical mechanical polishing pad

Abstract

To provide a chemical mechanical polishing pad.SOLUTION: A chemical mechanical polishing pad comprises a photocured polymer. The photocured polymer is the photoinitiated reaction product of a photocurable material comprising molecules having two or more functional groups. The functional groups include a thiol group and an ethylenically unsaturated group. For at least a portion of the molecules having the ethylenically unsaturated group, the ethylenically unsaturated group is a (meth)acrylate group. The (meth)acrylate groups comprise less than 70 mol% of total (meth)acrylate, thiol, and ethylenically unsaturated functional groups. The photocure includes reaction of the thiol group with the ethylenically unsaturated group. At least some of the molecules comprise three or more functional groups. The chemical mechanical polishing pad can be made by additive manufacturing using stereolithography.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for 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 on and removed from the surface of a semiconductor wafer. The thin layers of conductive, semiconductive, and dielectric materials can be deposited using a number of deposition techniques. Common deposition techniques in current wafer processing include, among others, physical vapor deposition (PVD), also known as sputtering, chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), and electrochemical plating. Common removal techniques include, among others, wet and dry isotropic and anisotropic etching.

[0003] As the layers of material are successively deposited and removed, the top surface of the wafer becomes non-flat. Since subsequent semiconductor processing (e.g., metallization) requires the wafer to have a flat surface, it is necessary to planarize the wafer. Planarization is useful for removing undesirable surface shapes and surface defects such as rough surfaces, agglomerated materials, damage to the crystal lattice, scratches, and contaminated layers or materials.

[0004] Chemical mechanical planarization, or chemical mechanical polishing (CMP), is a common technique used to planarize or polish workpieces such as semiconductor wafers. In conventional CMP, a wafer carrier, or polishing head, is attached to a carrier assembly. The polishing head holds the wafer and positions the wafer to contact the polishing layer of a polishing pad attached to 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. When the polishing pad rotates beneath the wafer, the wafer typically sweeps an annular polishing track, or polishing region, during which the surface of the wafer directly opposes the polishing layer. The wafer surface is polished and planarized by the chemical and mechanical action of the polishing layer and polishing medium on the surface.

[0005] Additive manufacturing of a polishing layer having a porous or three-dimensional pattern on a polishing surface has been proposed. For example, one approach uses a droplet jet 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 use in such droplet jet 3D printing may include acrylates, methacrylates, or epoxides as reactive groups for photocuring. See, for example, (Patent Document 1), (Patent Document 2), (Patent Document 3), (Patent Document 4), and (Patent Document 5). These chemical substances generally undergo chain-growth photocuring. This can result in materials having limited toughness and elongation properties that may lead to an undesirably high wear rate.

[0006] Another approach uses vat polymerization, including digital light processes and stereolithography approaches to additive manufacturing. See, for example, (Patent Document 6). Examples of photocurable systems useful in this method include compositions of acrylate block isocyanate monomers and acrylate monomers that can be photopolymerized via acrylate or methacrylate groups. See, for example, (Patent Document 7). Polymers cured by free radical-initiated reactions of acrylate or methacrylate groups with each other may have insufficient toughness and elongation and are thus not very suitable for use as the polishing layer of a chemical mechanical polishing pad.

[0007] It is desirable to obtain a chemical mechanical polishing pad manufacturable by additive manufacturing that has excellent toughness, elongation, and wear rate (e.g., toughness, elongation, and wear rate comparable to or better than those of commonly used chemical mechanical polishing pads).

[0008] Also desirable is an additive manufacturing process for manufacturing a polishing layer for a chemical mechanical polishing pad that enables better toughness, better elongation, wear rate, and higher flexibility in adjusting the mechanical properties of the polishing layer. In particular, it is desirable to obtain an additive manufacturing method for a polishing layer for chemical mechanical polishing that provides mechanical properties similar to those of a typical non-photocurable polishing layer of a chemical polishing pad.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

[0010] Disclosed herein is a chemical mechanical polishing pad comprising a photocurable polymer, wherein the photocurable polymer is a photoinitiation reaction product of a photocurable material containing a molecule having two or more functional groups, the functional groups include a thiol group and an ethylenically unsaturated group, and for at least a part of the molecule having an ethylenically unsaturated group, the ethylenically unsaturated group is a (meth)acrylate group. The (meth)acrylate group accounts for less than 70 mole percent of the total of the (meth)acrylate group, the thiol group, and the ethylenically unsaturated functional group. Photocuring includes the reaction of the thiol group and the ethylenically unsaturated group. At least a part of the molecule contains three or more functional groups.

[0011] Also disclosed is the polishing pad of the above paragraph formed from a method including preparing a photocurable material in a container, selectively curing a part of the photocurable material by irradiation to form a cured structure, selectively curing an additional part of the photocurable material by irradiation to further construct a 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 may be a polishing layer or a sub-pad layer, or both. [Brief Description of the Drawings]

[0012]

Figure 1

Figure 2

Best Mode for Carrying Out the Invention

[0013] The chemical mechanical polishing pad disclosed herein includes a polymer in which the curing of the polymer does not result solely from a free radical-initiated reaction of two (meth)acrylate groups, but includes a reaction between a thiol group and a (meth)acrylate group. As used herein, "(meth)acrylate" is a term that refers to a genus that includes acrylate, methacrylate, or a mixture containing both acrylate and methacrylate.

[0014] The reaction mixture used to form the photocurable polymer may be particularly suitable for additive manufacturing, including stereolithography or vat polymerization.

[0015] The photocurable polymer can be formed by the reaction of a molecule having two or more functional groups, where the functional groups are ethylenically unsaturated groups and thiol groups. For example, the molecule having two or more functional groups can contain both at least one ethylenically unsaturated group and at least one thiol group. This molecule can be regarded as an AB-type molecule. As another example, as the molecule having two or more functional groups, there are mentioned 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), or in combination with molecule (B), or in combination with both molecule (A) and molecule (B). To crosslink, at least a part 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 crosslink density can be controlled by the relative amount of the bifunctional molecule (i.e., the molecule having two ethylenically unsaturated groups or the molecule having two thiol groups) with respect to the more highly functional molecule (e.g., the molecule having more than two ethylenically unsaturated groups or the molecule having more than two thiol groups). At least a part of the ethylenically unsaturated groups is a (meth)acrylate group.

[0016] Molecule (A) can include an oligomer (also called a prepolymer), a monomer, or a mixture thereof. Molecule (B) can include an oligomer (also called a prepolymer), a monomer, or a mixture thereof. By selecting the structures of the oligomer and the monomer and their relative amounts, the properties of the photocurable polymer can be adjusted. For example, the rigid polyfunctional alkene used as molecule (A) can improve the hardness or toughness. When the oligomer molecule (A) is used, it may be useful for controlling the viscosity while avoiding the use of a solvent that may need to be removed after curing when mixed with the monomer molecule (A).

[0017] The molecule (A) can contain, for example, a vinyl group, a vinyl ether group, an allyl group, an allyl ether, an allyl ester, maleimide, vinyl sulfone, norbornene, etc. However, the reaction mixture contains at least some (meth)acrylate groups in the molecule (A), (AB), or both (A) and (AB). Examples of the monomer molecule (A) include 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, N,N'-methylenebis(acrylamide). Examples of the monomer (A) having a (meth)acrylate group include aliphatic or aromatic compositions between (meth)acrylate groups, for example, aliphatic polyfunctional acrylates such as 1,3-propanediol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate; alkylene oxide polyfunctional acrylates such as ethylene glycol diacrylate, di(ethylene glycol) diacrylate, tri(ethylene glycol) diacrylate, tri(propylene glycol) diacrylate; cycloaliphatic acrylates such as 2-[5-[(acryloyloxy)methyl]-5-ethyl-1,3-dioxan-2-yl]-2-methylpropyl acrylate, tricyclodecane dimethanol diacrylate; and aromatic (meth)acrylates such as biphenyl-4,4'-diyl bis(2-methylacrylate). These monomer molecules (A) can be used as a mixture with oligomer molecules (A).The oligomeric molecule (A) may be, for example, poly(ethylene glycol) diacrylate, poly(propylene glycol) diacrylate, poly(tetramethylene oxide) diacrylate, poly(dimethylsiloxane) diacrylate, polycaprolactone diacrylate, or an oligomer containing urea, urethane, or thiourea.

[0018] Advantageously, the polyfunctional isocyanate can form a molecule A containing urea, urethane, or thiourea by reacting with a molecule (i.e., an end-capping agent) containing an ethylenically unsaturated group (e.g., a (meth)acrylate group) and at least one nucleophilic functional group (e.g., amine, hydroxy, thiol, etc.). Examples of capping agents include allylphenol (e.g., 2-allylphenol, 4-allylphenol, eugenol, isoeugenol), alkylene glycol allyl ether (e.g., ethylene glycol allyl ether), alkylene glycol monovinyl ether (e.g., ethylene glycol monovinyl ether, butanediol monovinyl ether), allyl alcohol (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, hydroxyalkyl (meth)acrylate (e.g., hydroxyethyl acrylate, hydroxyethyl methacrylate), hydroxynorbornene 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 groups, vinyl ether groups, allyl groups, allyl ethers, allyl esters, maleimides, norbornenes, (meth)acrylates, provided that at least a portion of the ethylenically unsaturated groups in the reaction mixture include (meth)acrylate groups. Allyl, allyl ether, and allyl ester can provide an excellent balance of storage stability and photoreactivity. As used herein, an allyl group is the group -CH2 -CH=CH 2 means. Monosubstituted alkenes react rapidly with thiol groups, while disubstituted alkenes such as crotyl alcohol and trans-3-hexen-1-ol react at a slow rate.

[0020] For example, the following reaction scheme can be used to prepare molecule (A):

Chemical formula

[0021] R 1 is a linking group. For example, R 1 may contain an aliphatic group or an aromatic group or both. For example, R 1 can include divalent alkyl, cycloalkyl, divalent aryl, divalent arylalkyl, or may contain carbon and heteroatoms such as nitrogen. For example, R 1 contains methylenediphenyl, isophorone, 2,4-toluene, 2,6-toluene, hexamethyl, or a uretdione skeleton formed from the dimerization of two isocyanate groups. Alternatively, R 1 may be an oligomeric group containing two or more repeating units, three or more, up to 150 repeating units. The repeating units may be, for example, alkylene oxides such as ethylene oxide, propylene oxide, or tetramethylene oxide; lactones such as caprolactone; hydrocarbons and saturated and unsaturated forms of diene units such as butadiene, isoprene, ethylidene norbornene, dicyclopentadiene, vinyl norbornene; siloxanes such as dimethylsiloxane; and fluorinated units such as vinylidene fluoride and tetrafluoroethylene. R 2 is a linking group. For example, R 2 may contain an aliphatic group or an aromatic group or both. For example, R 2 may be divalent alkyl; divalent aryl; divalent arylalkyl such as benzyl, phenyl, alkyl; or an alicyclic group such as cyclohexyl. R 2 is initially of the formula [Y] b -R2 -[C=C] c is provided by an end-capping agent. Usually, the end-capping agent may contain at least one nucleophilic group (e.g., OH, NH 2 , or SH) and an ethylenically unsaturated group. Examples of end-capping agents that provide (meth)acrylate include hydroxyalkyl (meth)acrylates (e.g., hydroxyethyl acrylate, hydroxyethyl methacrylate).

[0022] 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 (e.g., a (meth)acrylate group). 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; para-phenylene diisocyanate; xylylene diisocyanate; isophorone diisocyanate; hexamethylene diisocyanate; 4,4'-dicyclohexylmethane diisocyanate; cyclohexane diisocyanate; and mixtures thereof, etc.

[0023] As another example, the molecule (A) may include an oligomer of a urethane or urea prepolymer having two or more ethylenically unsaturated groups; a polysiloxane such as a polydimethylsiloxane having two or more ethylenically unsaturated groups (e.g., (meth)acrylate groups); or a polyalkylene glycol having two or more ethylenically unsaturated groups. When the chemistry of urethane or urea is desired, such a molecule (A) oligomer can be derived from an isocyanate prepolymer such as a polyalkylene glycol end-capped with an isocyanate group or a small molecule diisocyanate. Examples of diisocyanates used directly or as prepolymer end-caps include the following. The isocyanate-terminated urethane prepolymer can have 2 to 30% by weight of unreacted isocyanate (NCO) groups. The prepolymer polyol used to form the polyfunctional isocyanate-terminated urethane prepolymer can be selected from the group consisting of diols, polyols, polyol diols, their copolymers, and mixtures thereof. For example, the prepolymer polyol can be a polyether polyol (e.g., poly(oxytetramethylene) glycol, poly(oxypropylene) glycol, and mixtures thereof); a polycarbonate polyol; a polyester polyol; a polycaprolactone polyol; mixtures thereof; and mixtures thereof with one or more low molecular weight polyols selected from the group consisting of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 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; and can be selected from the group consisting of.For example, the prepolymer polyol can be selected from the group consisting of polytetramethylene ether glycol (PTMEG), ester polyols (such as ethylene adipate, butylene adipate, etc.), polypropylene ether glycol (PPG), polycaprolactone polyol, their copolymers, and mixtures thereof. For example, the prepolymer polyol can be selected from the group consisting of PTMEG and PPG. Examples of commercially available PTMEG-based isocyanate-terminated urethane prepolymers include Imuthane® prepolymers (available from COIM USA, Inc., such as PET-80A, PET-85A, PET-90A, PET-93A, PET-95A, PET-60D, PET-70D, PET-75D); Adiprene® prepolymers (available from Lanxess, such as LF800A, LF900A, LF910A, LF930A, LF931A, LF939A, LF950A, LF952A, LF600D, LF601D, LF650D, LF667, LF700D, LF750D, LF751D, LF752D, LF753D, and L325); Andur® prepolymers (available from Anderson Development Company, such as 70APLF, 80APLF, 85APLF, 90APLF, 95APLF, 60DPLF, 70APLF, 75APLF). Non-TDI-based isocyanate-terminated urethane prepolymers can also be used. For example, isocyanate-terminated urethane prepolymers include those formed by the reaction of 4,4'-diphenylmethane diisocyanate (MDI) with a polyol such as polytetramethylene glycol (PTMEG), or a diol such as 1,4-butanediol (BDO), and are acceptable.Modified MDI products such as polycarbodiimide-modified MDI (e.g., Isonate 143L), and pseudo prepolymers of MDI reacted with low molecular weight diols such as 1,2-propylene glycol, 1,3-propylene glycol, 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, tripropylene glycol, or combinations thereof (e.g., Isonate 181) may be used. Examples of commercially available MDI, polymeric MDI, and MDI prepolymers include ISONATE™ 143L, ISONATE™ 143LP, ISONATE™ 181, ISONATE™ 240, ISONATE™ M143, ISONATE™ M320, ISONATE™ M340, ISONATE™ 342, ISOBIND™ 1002, ISOBIND™ 1013, ISOBIND™ 1014, ISOBIND™ 1088, ISOBIND™ 1100, ISOBIND™ 1100S, ISOBIND™ 1200R, PAPI™ 135, PAPI™ 135C, PAPI™ 17, PAPI™ 20, PAPI™ 27, PAPI™ 580N, PAPI™ 6146, PAPI™ 901, PAPI™ 94, POLYMERIC MDI 199, POLYMERIC MDI 253, VORANATE™ M200, VORANATE™ M220, VORANATE™ 229, VORANATE™ 229N, VORANATE™ M230, VORANATE™ M2940, VORANATE™ M580, VORANATE™ M595, VORANATE™ M600, VORANATE™ M647, VORANATE™ SD100, VORANATE™ SD100 IF from The Dow Chemical Company. The prepolymer can contain at least two isocyanate groups.Some commercially available products may contain an undisclosed mixture of a molecule having two isocyanate groups and a molecule having more than two isocyanate groups. An example of a commercially available prepolymer that is thought to have more than two isocyanates per molecule is Desmodur N-3400 from Covestro AG.

[0024] 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-diyl dimethanethiol), mercaptopropionic acid esters (e.g., ethylene glycol bis(3-mercaptopropionate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), tris[2-(3-mercaptopropionyloxy)ethyl] isocyanurate), thioglycolate esters (e.g., 1,4-butanediol bis(thioglycolate)), mercaptoacetate esters (e.g., pentaerythritol tetrakis(mercaptoacetate)), aromatic dithiols, arylalkyls (e.g., aryls having alkylthiol pendant groups) (e.g., 1,3-benzenedimethanethiol, 1,4-benzenedimethanethiol, 4,4'-bis(mercaptomethyl)biphenyl) and thiol-terminated oligomers (e.g., poly(ethylene glycol) dithiol, poly(dimethylsiloxane) dithiol, or urethane or urea oligomers).

[0025] Examples of AB type molecules include allyl mercaptan, and oligomers or prepolymers capped with both an ethylenically unsaturated group and a thiol group. Oligomers capped with both an ethylenically unsaturated group and a thiol group can be prepared as described above, but provide one capping group containing ethylenic unsaturation and one capping group having a thiol functional group.

[0026] The photocurable polymer can be formed from a reaction mixture containing one or more molecules (A), one or more molecules (B), and a photoinitiator. The photoinitiator absorbs radiation of an activation wavelength (for example, ultraviolet light of 200 to 500, 340 to 390 (for example, 385 nanometers (nm))).

[0027] The reaction mixture further comprises a photoinitiator. According to a first embodiment, the photoinitiator is a free radical generator. In that case, the curing involves the reaction of a thiol group with a (meth)acrylate to form a thiol-ether bond. In this case, the curing may also involve the reaction of (meth)acrylate groups with other (meth)acrylate groups. Examples of 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. As another example, the photoinitiator can generate a base that, when irradiated, can deprotonate one of the thiol groups to react the thiol with a meth(acrylate) group. This approach can avoid side reactions between (meth)acrylate groups. 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 (e.g., Fujifilm WPBG-018). When the photo-base generator does not absorb at the applicable wavelength, for example, thioxanthone species or other photo-base generators that absorb at the desired wavelength can be used as photosensitizers. When the photo-base generator generates radicals in addition to the base, radical inhibitor species such as 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) can be used to selectively suppress radical side reactions while enabling base-catalyzed reactions.The amount of the photoinitiator in the reaction mixture may be, based on the total weight of the reaction mixture, for example, from 0.1% by weight, 0.2% by weight, 0.3% by weight, 0.4% by weight, or 0.5% by weight, up to 5% by weight, up to 4% by weight, up to 3% by weight, up to 2% by weight, or up to 1.5% by weight.

[0028] The molar ratio of the ethylenically unsaturated groups, at least a part of which is a (meth)acrylate group (for example, derived from molecule (A)), to the thiol groups (for example, of molecule (B)) may 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 may be about 1:1. The molar percentage of the meth(acrylate) group is based on the total of the (meth)acrylate group, the thiol group, and the ethylenically unsaturated functional group [(the number of moles of the (meth)acrylate group + the number of moles of other ethylenically unsaturated groups + the total number of moles of the thiol group)], and may be less than 70%, or less than 60%, or less than 55%, and preferably is at least 1%. In certain embodiments, such as when a photo-base generator is used, the molar ratio of the meth(acrylate) group based on the total number of moles of the (meth)acrylate group, other ethylenically unsaturated groups, and thiol groups is preferably at least 30%, more preferably at least 40%.

[0029] The reaction mixture may optionally contain a UV absorber in addition to the photoinitiator. The UV absorber can facilitate the adjustment of the light transmission (i.e., the curing depth) of the reaction mixture. The UV absorber can absorb light at a wavelength (for example, 385 nm) used in an additive manufacturing device. Examples of the UV absorber include 2,2'-dihydroxy-4,4'-dimethoxybenzophenone (DHDMBP) and avobenzone. The amount of the ultraviolet absorber is greater than 0, at least 0.1% by weight, at least 0.2% by weight, at least 0.3% by weight, at least 0.4% by weight, or at least 0.5% by weight, up to 10% by weight, up to 5% by weight, or up to 2% by weight, based on the total weight of the reaction mixture.

[0030] The reaction mixture may optionally contain a liquid reactive diluent containing a group (e.g., ethylenically unsaturated group or thiol) that reacts with other components of the reaction mixture. This liquid reactive diluent can lower 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 formation of the polishing layer. Such removal may cause shrinkage. One type of liquid reactive diluent includes molecules containing ethylenically unsaturated groups such as (meth)acrylates, allyls, allyl ethers, vinyls, and vinyl ether compounds. Examples of these include, but are not limited to, alkyl (meth)acrylates, hydroxyalkyl (meth)acrylates where the alkyl has 1 to 4 carbon atoms, vinyltoluene, isononyl (meth)acrylate, (meth)acrylic acid, diallyl isophthalate, diallyl terephthalate, butanediol divinyl ether, N-vinylpyrrolidone, butanediol monovinyl ether, ethylene glycol vinyl ether, vinyl acetate, 1-vinylimidazole, 2-vinylpyrazine, vinyl pivalate, vinyl propionate, vinyl stearate, vinyl decanoate, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, allyl ether, allyl hexanoate, allyl acetate, allyl butyl ether, allyl mercaptan, pentaerythritol allyl ether, allyl methyl carbonate, allyl phenyl ether, allyl heptanoate, allyl butyrate, allyl methyl sulfone, allyl sulfide, tetrahydrofurfuryl acrylate, N,N-dimethylacrylamide, N,N-dimethylacrylamide, isobornyl acrylate, 2-hydroxyethyl acrylate, and 2-hydroxyethyl methacrylate. Another type of liquid reactive diluent can include liquid thiol compounds such as 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, mercaptopropionic acid, and mercaptopropionic acid esters.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.

[0031] The reaction mixture may also contain a non-reactive diluent (e.g., solvents such as dimethyl sulfoxide (DMSO), dimethylformamide (DMF), N-methylpyrrolidone (NMP), acetone, etc.) to reduce viscosity. However, this may add a solvent removal step to the process of forming the polishing layer.

[0032] The reaction mixture may also contain non-reactive components that are desired to be included in the polishing layer. This component can impart functionality such as mechanical reinforcement, porosity, or additional abrasive for polishing. Examples of these include inorganic particles such as silica, ceria, titania; polymer beads or particles; expandable polymer microspheres, etc.

[0033] An example of a reaction scheme for forming a composition useful as an element of the polishing pad disclosed herein using a radical-generating photoinitiator is as follows.

Chemical formula

[0034] When a photo-base generator is used, a representative reaction scheme is as follows:

Chemical formula

[0035] The cured polymer described herein that can be used as the polishing layer of the polishing pad has a glass transition temperature (T g ) that can be selected from the maximum tanδ temperature from, for example, -20 °C or -10 °C to a maximum of 120 °C, a maximum of 100 °C, a maximum of 70 °C, a maximum of 60 °C, or a maximum of 50 °C, in accordance with ASTM D5279-21. The cured polymer described herein that can be used as the polishing layer of the polishing pad can have a tensile modulus of, for example, from 1 megapascal, from 5 megapascals, or from 10 megapascals to a maximum of 700 megapascals, a maximum of 500 megapascals, or a maximum of 400 megapascals (MPa), in accordance with ASTM D412-05. The cured polymer described herein that can be used as the polishing layer of the polishing pad can have an elongation in accordance with ASTM D412 of, for example, from 20%, 50%, 70%, or 100% to a maximum of 500%, a maximum of 450%, a maximum of 400%, or a maximum of 300%. The cured polymer described herein that can be used as the polishing layer of the polishing pad can have toughness in accordance with ASTM D412 of, for example, from 1 MPa, 2 MPa, or 5 MPa to a maximum of 30 MPa or a maximum of 20 MPa. The cured polymer described herein that can be used as the polishing layer of the polishing pad can have a cut rate of, for example, greater than 0 to a maximum of 2 millimeters per hour, a maximum of 1.5 millimeters per hour, or a maximum of 1 millimeter per hour (mm / h).

[0036] Also provided is a method of manufacturing a chemical mechanical polishing pad disclosed in this specification. This method includes preparing a photocurable material in a container, selectively curing a part of the photocurable material by irradiating it with radiation of an activation wavelength to form a cured structure, further constructing a cured structure by selectively curing an additional part of the photocurable material by irradiation, repeating selective curing by irradiation until the cured structure has the form of an element of the polishing pad, wherein the photocurable material includes molecules having two or more functional groups, the functional groups being ethylenically unsaturated groups (at least a part of which is a (meth)acrylate group) and thiol groups, and at least a part of the molecules includes three or more functional groups, and the ethylenically unsaturated groups and the thiol groups react upon irradiation. The photocurable material in the container can be in a liquid state. The photocurable material in the container can have fluidity under printing conditions. The photocurable material in the container can be spreadable.

[0037] Thus, in one example, as shown in FIG. 1, a 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 contains the reaction mixture 10 described herein (i.e., the reaction mixture contains a mixture of molecules having two or more functional groups, which functional groups are ethylenically unsaturated groups (at least some of which are (meth)acrylate groups) and thiol groups, and the reaction is a reaction between an ethylenically unsaturated group and a thiol group). This 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 activation wavelength. The activating radiation 7 passes through the portion 3 of the container 1 in an image-like manner and photocures a portion of the reaction mixture 10 that is at or just above the bottom of the container 1. Optionally, a layer 4 may be provided on the surface 3. The layer 4 can prevent the adhesion of the photocurable polymer to the layer 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. A first layer 11 of the photocurable polymer is formed under the build platform 2. The build platform 2 and the first layer 11 are raised so that the reaction mixture 10 can flow under the first layer 11. The radiation again passes through the surface 3 in an image-like manner to form a second layer 12 of the photocurable polymer. By repeating this until the desired elements (e.g., a polishing layer) of the polishing pad are completely formed, additional layers are formed.

[0038] In another example shown in FIG. 2, the top-down additive manufacturing apparatus includes a container 1. The container 1 contains the reaction mixture 10 described herein. A layer of the reaction mixture 10 is supplied onto the build platform 2 and is imagewise exposed to radiation 7 to form a first layer 11 of photocurable polymer on the build platform 2. The build platform 2 is then lowered, and an additional layer of the reaction mixture 10 can cover the first layer 11. A recoating blade 8 may 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 imagewise exposed to radiation 7 to form a second layer 12 of photocurable polymer on the first layer 11. This is repeated until the desired polished layer is completely formed, forming additional layers.

[0039] The viscosity of the reaction mixture under printing conditions can be from 0.01 Pascal seconds (Pa·s) up to a maximum of 20 Pa·s, or up to a maximum of 10 Pa·s. The printing conditions can be from room temperature up to a maximum of 200 °C, 150 °C, 100 °C, 80 °C, 50 °C, but need to be lower than the boiling point and thermal decomposition point of the components of the reaction mixture. For energy efficiency, printing conditions at room temperature may be advantageous. The reaction mixture can be in liquid form.

[0040] The methods disclosed herein can be used to provide a polishing 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 polishing surface. The grooves can have a depth, for example, from 0.1 mm, 0.2 mm, or 0.3 mm up to a maximum of 1.5 mm, 1.2 mm, or 1 mm. The grooves can have a width, for example, from 0.05 mm, 0.1 mm, 0.2 mm, or 0.3 mm up to a maximum of 1 mm, 0.8 mm, or 0.6 mm. The protrusions project above the base upper surface of the polishing pad. They can be non-hollow or hollow cylindrical, cubic, pyramidal, or of irregular cross-section (e.g., lobe-shaped). The protrusions can have a height from 0.05 mm or 0.1 mm up to a maximum of 2 mm or 1.5 mm. The protrusions can include openings in the side walls. The protrusions can include a polished surface raised above the upper part of the polishing layer on a support having a gap between the polished surface and the base upper surface of the polishing pad.

[0041] The chemical mechanical polishing pads disclosed herein can include a sub-pad located on the opposite side of the polishing surface of the polishing layer. The polishing layer can be adhered to the sub-pad after manufacturing the sub-pad using an adhesive material. Alternatively, the composition of the photosensitive reaction mixture used to form the sub-pad can be adjusted to obtain desired properties, and the entire pad can be formed by additional printing. 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 structures.

[0042] Examples of polymer materials for the sub-pad layer include polyurethane, polycarbonate, polysulfone, nylon, epoxy resin, polyether, polyester, polystyrene, acrylic polymer, polymethyl methacrylate, polyvinyl chloride, polyvinyl fluoride, polyethylene, polypropylene, polybutadiene, polyethyleneimine, polyethersulfone, polyamide, polyetherimide, polyketone, silicone, their copolymers (such as polyether-polyester copolymers), and combinations or blends thereof. The sub-pad can also be formed by additive manufacturing as described herein. The sub-pad can be formed using thiol-ene curing from a reaction mixture described herein that is selected to provide higher compliance than that found in the polishing layer. The sub-pad can be formed from a reaction mixture comprising a polymer precursor (monomer, oligomer, or mixture thereof) having ethylenically unsaturated groups and thiol groups as described herein. When the sub-pad is formed by additive manufacturing, the sub-pad and the polishing layer can be formed sequentially in reaction vessel 1 while changing the reaction mixture as it moves from one layer to another. For example, the polishing layer can be formed as described above. When the polishing layer is formed, reaction mixture 10 can be removed from vessel 1 and a new reaction mixture can be added. The same exposure process can be performed to form additional layers on the polishing layer. Alternatively, the sub-pad can be formed first, and then the polishing layer can be formed by additive manufacturing on the sub-pad as the substrate. For example, a process can be performed where the sub-pad is formed by additive manufacturing and then the polishing layer is formed on the sub-pad on the build platform. As another example, a pre-formed sub-pad on the build platform can be provided and the polishing layer can be formed on the sub-pad by additive manufacturing as described herein.

[0043] A chemical mechanical polishing pad can include a window in the polishing layer. The window is formed of a material that is transparent to the wavelength used for endpoint detection during use of the polishing pad. A chemical mechanical polishing pad including a window can also be formed using additive manufacturing. For example, the polishing layer from a reaction mixture can be formed around a window material disposed on a build platform. As another example, the polishing layer can be formed with an opening where the window will later be disposed. As yet another alternative, the window itself can be formed by additive manufacturing. For example, the window can first be formed by additive manufacturing within a container 1 of the apparatus, and then the polishing layer can be formed by additive manufacturing around the window. As another example, a polishing layer with a gap for the window can be formed by the additive manufacturing disclosed herein, and then the window can be formed by additive manufacturing in the gap. The window material can be, for example, polyurethane, acrylic polymer, cyclic olefin copolymer (such as TOPAS 8007, etc.). The use of a polyurethane material may be useful in pads where the polishing layer, sub-pad layer, or both are also polyurethane. A specific set of examples of aliphatic polyurethanes for windows can be found, for example, in (Patent Document 8).

Example

[0044] In the virtual example, the reaction mixture includes a small molecule (A) that is component 1 - diallyl isophthalate (DAIP) or 2 - hydroxyethyl acrylate (HEA); component 2 - oligomeric molecules (A2x is a prepolymer based on a low - molecular - weight diol terminated with MDI and then reacted with HEA, and A2y is derived from a prepolymer based on PTMEG terminated with TDI and then reacted with HEA); component 3 - a molecule (B) compound having more than two thiol functional groups that provides cross - linking (PTMP is pentaerythritol tetrakis(3 - mercaptopropionate)); component 4 - a molecule (B) dithiol - functional compound that provides chain extension (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 weight percent based on the total weight of the reaction mixture. The reaction mixture may include a reaction mixture containing these components. The amounts of components 1 - 4 and what they are are shown in Table 1. The weight percentages are based on the total weight of the reaction mixture. All examples were prepared at a molar ratio of 1:1 of ethylenically unsaturated groups to thiol groups.

[0045]

Table 1

[0046] The present disclosure further encompasses the following aspects.

[0047] Aspect 1: A chemical mechanical polishing pad comprising a photocurable polymer, wherein the photocurable polymer is a photo-initiated reaction product of a photocurable material containing a molecule having two or more functional groups, the functional groups including a thiol group and an ethylenically unsaturated group, and for at least a part of the molecules having an ethylenically unsaturated group, the ethylenically unsaturated group is a (meth)acrylate group, the (meth)acrylate group accounting for less than 70 mole percent of the total of the (meth)acrylate group, thiol group, and ethylenically unsaturated functional group, the photocuring including a reaction between the thiol group and the ethylenically unsaturated group, and at least a part of the molecules containing three or more functional groups. A chemical mechanical polishing pad.

[0048] Aspect 2: The chemical mechanical polishing pad according to Aspect 1, wherein the molecule having two or more functional groups includes 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 part of the first molecule contains at least three or more ethylenically unsaturated groups, or at least a part of the second molecule contains three or more thiol groups.

[0049] Aspect 3: The chemical mechanical polishing pad according to Aspect 1, wherein the molecule includes a heterotelechelic molecule having a (meth)acrylate group and a thiol group.

[0050] Aspect 4: The chemical mechanical polishing pad according to any one of Aspects 1 to 3, wherein the reaction mixture includes a photoinitiator that generates radicals when exposed to radiation of an activation wavelength.

[0051] Aspect 5: The chemical mechanical polishing pad according to any one of Aspects 1 to 4, wherein the reaction mixture includes a photoinitiator that generates a base upon exposure to radiation of an activation wavelength.

[0052] Aspect 6: The chemical mechanical polishing pad according to Aspect 2, wherein the first molecule includes a reaction product of a polyisocyanate containing an oligomer, a polyfunctional isocyanate monomer, or a mixture thereof, and a (meth)acrylate functional end-capping agent.

[0053] Aspect 7: The chemical mechanical polishing pad according to aspect 2, wherein the first molecule includes an oligomer containing a (meth)acrylate group, and the second molecule includes one or more of an alkyl polyfunctional thiol, an aromatic polyfunctional thiol, and a thiol-terminated oligomer having two or more thiol groups.

[0054] Aspect 8: The chemical mechanical polishing pad according to any one of aspects 1 to 7, comprising less than 0.05 weight percent of polishing particles based on the total weight of the polishing pad.

[0055] Aspect 9: The chemical mechanical polishing pad according to any one of aspects 1 to 8, wherein the (meth)acrylate group occupies less than 70 mole percent of the functional groups.

[0056] Aspect 10: The polishing pad according to any one of aspects 1 to 9, formed from a method comprising preparing a 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 construct a cured structure, and repeating the selective curing by irradiation until the cured structure has the form of an element of the polishing pad.

[0057] Aspect 11: The polishing pad according to aspect 10, wherein the molecule having two or more functional groups includes a first molecule having two or more (meth)acrylate groups and a second molecule having two or more thiol groups, the first molecule is a monomer, an oligomer, or a mixture of two or more thereof, and the second molecule is a monomer, an oligomer, or a mixture thereof.

[0058] All ranges disclosed in this specification include their endpoints, and the endpoints can be combined independently of each other (e.g., a range of "up to 25% by weight, more specifically 5% to 20% by weight" includes the endpoints and all intermediate values in the range of "5% to 25% by weight", etc.). Further, ranges can be formed by combining the recited upper and lower limits (e.g., combining "at least 1% by weight or at least 2% by weight" with "up to 10 or 5% by weight" can result in ranges of "1 to 10% by weight" or "1 to 5% by weight" or "2 to 10% by weight" or "2 to 5% by weight").

[0059] The present disclosure can be any of including, consisting of, or consisting essentially of any suitable components disclosed herein. The present disclosure can additionally or alternatively be formulated so as to not include, or substantially not include, any component, material, ingredient, adjuvant, or species that is used in prior art compositions or that is not necessary for achieving the functions and purposes of the present disclosure.

[0060] All patents, patent applications, and other references cited are hereby incorporated by reference in their entirety. However, in the event of a conflict or contradiction between the terms of the incorporated reference and the terms of the present application, the terms of the present application shall prevail over the conflicting terms of the incorporated reference.

[0061] Unless otherwise specified herein, all test standards are the latest standards in effect as of the filing date of the present application, or, if priority is claimed, the latest standards in effect as of the filing date of the earliest priority application in which the test standard appears.

Description of Reference Numerals

[0062] 1 Container 2 Build Platform 3 Transparent Portion 4 Layer 7 Activating Radiation 8 Recoating Blade 10 Reaction Mixture 11 First Layer 12 The second layer

Claims

1. 1. A chemical mechanical polishing pad comprising a photocured polymer, the photocured polymer being a photoinitiated reaction product of a photocurable material comprising molecules having two or more functional groups, the functional groups comprising thiol groups and ethylenically unsaturated groups, wherein for at least a portion of the molecules having ethylenically unsaturated groups, the ethylenically unsaturated groups are (meth)acrylate groups, the (meth)acrylate groups comprising less than 70 mole percent of the sum of the (meth)acrylate groups, thiol groups, and ethylenically unsaturated functional groups, and the photocuring comprises a reaction of the thiol groups with the ethylenically unsaturated groups, wherein at least a portion of the molecules comprise three or more functional groups.

2. 2. The chemical mechanical polishing pad of claim 1, wherein the molecules having two or more functional groups include first molecules having two or more of the ethylenically unsaturated groups and second molecules having two or more of the 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 of claim 1 , wherein the molecule comprises a heterotelechelic molecule having a (meth)acrylate group and a thiol group.

4. 10. The chemical mechanical polishing pad of claim 1, wherein the reaction mixture includes a photoinitiator that generates radicals upon exposure to radiation at an activating wavelength.

5. 10. The chemical mechanical polishing pad of claim 1, wherein the reaction mixture includes a photoinitiator that generates a base upon exposure to an activating wavelength of radiation.

6. 3. The chemical mechanical polishing pad of claim 2, wherein the first molecule comprises a reaction product of a polyisocyanate, including an oligomer, a multifunctional isocyanate monomer, or a mixture thereof, and a (meth)acrylate-functional endcapping agent.

7. 3. The chemical mechanical polishing pad of claim 2, wherein the first molecule comprises an oligomer containing a (meth)acrylate group and the second molecule comprises one or more of an alkyl polyfunctional thiol, an aromatic polyfunctional thiol, a polyfunctional mercaptopropionate ester, a polyfunctional thioglycolate ester, a polyfunctional mercaptoacetate ester, a thiol-terminated oligomer having two or more thiol groups.

8. 2. The chemical mechanical polishing pad of claim 1, wherein the (meth)acrylate groups account for less than 55 mole percent of the total of (meth)acrylate groups, thiol groups, and ethylenically unsaturated functional groups.

9. 10. The polishing pad of claim 1, formed from a method including providing a photocurable material in a container; selectively curing a portion of the photocurable material by irradiation to form a hardened structure; selectively curing additional portions of the photocurable material by irradiation to further build up the hardened structure; and repeating the selective curing by irradiation until the hardened structure has the form of an element of the polishing pad.

10. The photocurable material to be prepared is i) a monomer or oligomer or a mixture thereof having two or more ethylenically unsaturated groups, at least a portion of which is a (meth)acrylate group; and ii) Monomers or oligomers having two or more thiol groups, or mixtures thereof 10. The polishing pad of claim 9, comprising:

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