Methods for manufacturing low specific gravity polishing pads

Abstract

A polishing pad for chemical mechanical polishing is disclosed, comprising: a polishing layer comprising a polymer matrix, the polymer matrix being a reaction product of an isocyanate-terminated oligomer or polymer and a curing agent blend comprising two or more polyamine curing agents, wherein pores are present in the polymer matrix, such pores being formed by the expansion of pre-expanded fluid-filled polymer microspheres, such expansion occurring during the reaction of the isocyanate-terminated oligomer or polymer with the two or more curing agents, wherein the polishing layer is characterized by one or more of the following: a viscous modulus (G”) at 104°C to a shear loss modulus (G”) at 150°C having a ratio of at least 5:1; and a specific gravity of the polishing layer being less than or equal to 95% of the calculated specific gravity of the isocyanate-terminated oligomer or polymer, the curing agent blend, and the pre-expanded fluid-filled polymer microspheres.

Description

Technical Field

[0001] This application relates to polishing pads that can be used to polish and planarize substrates such as semiconductor substrates or disks. Background Technology

[0002] Chemical mechanical planarization (CMP) is a polishing process used to planarize or flatten the building layers of integrated circuits to precisely construct multilayer three-dimensional circuits. The layers to be polished are typically thin films (e.g., less than 10,000 angstroms) already deposited on the underlying substrate. The purpose of CMP is to remove excess material from the wafer surface to produce an extremely flat layer of uniform thickness, with this uniformity extending throughout the entire wafer area. Controlling the removal rate and removal uniformity is crucial.

[0003] CMP uses polishing pads and polishing fluids (e.g., slurries) to polish substrates (e.g., wafers). The fluid or slurry typically contains nanoscale particles. The polishing pad can be mounted on a rotating plate. The substrate (e.g., a wafer) can be mounted in a separate jig or holder, which may have a separate rotation mechanism. The polishing pad and substrate are pressed against each other at a high relative velocity (i.e., a high shear rate) under a controlled load. The slurry is provided between the polishing pad and the substrate. This shearing, along with any slurry particles trapped at the pad / wafer junction, abrades the substrate surface, causing material to be removed from the substrate.

[0004] The polishing pad may comprise multiple layers: (a) an upper layer (i.e., the polishing layer) that contacts the wafer to provide polishing action; (b) one or more sub-layers with greater compressibility that are combined to adjust the pad-wafer compliance; and optionally (c) an adhesive layer for connecting (a) and (b) and for attaching the entire pad to a rotating pressure plate. This upper polishing layer is crucial for the success of the CMP process.

[0005] Many CMP pads contain a polishing layer comprising closed-cell polyurethane, which is formed by reacting a polyol with an isocyanate to form an isocyanate-terminated prepolymer, followed by mixing with a curing agent and polymer micro-components, the mixing of which results in a reaction to form the polishing layer. See, for example, U.S. Patent Nos. 5,578,362 and 10,391,606. U.S. Patent No. 9,586,304 discloses a mixture of pre-expanded and unexpanded fluid-filled polymer microspheres that improves the uniformity of polymer microsphere distribution and can provide a pad with a relatively low specific gravity and density. However, the use of pre-expanded and unexpanded fluid-filled polymer microspheres can result in a bimodal distribution of pores in the final pad (e.g., where the unexpanded fluid-filled polymer microspheres expand to a different size than the pre-expanded fluid-filled polymer microspheres).

[0006] The goal is to continuously and efficiently produce polishing layers with low variability in properties (including one or more of pore size distribution and specific gravity). It is also desirable to obtain polishing pads with polishing layers exhibiting low specific gravity and a unimodal pore size distribution. Summary of the Invention

[0007] This document discloses a method for forming multiple polishing layers for a chemical mechanical polishing pad. The method includes: filling a mold with a mixture comprising an isocyanate-functionalized prepolymer, pre-expanded fluid-filled polymer microspheres, and a curing agent blend, wherein the curing agent blend comprises a monoaromatic polyamine curing agent and a polyamine curing agent having two or more aromatic rings, wherein the mixture is characterized by heat released from the reaction between the isocyanate-functionalized prepolymer and the curing agent; curing the mixture in the filled mold at a curing temperature to form a polymer block comprising a cured polymer matrix and pores formed by further expansion of the pre-expanded fluid-filled polymer microspheres, the further expansion being caused by heat from the curing and heat released from the reaction, wherein the mixture remains soft for a period of time in the central portion of the block to allow for the further expansion; and cutting the polymer block to form multiple polishing layers. The multiple polishing layers may be characterized in that the portion of the multiple polishing layers cut from the central portion of the block has a specific gravity more than 5% lower than that of the polishing layers cut from the edges of the block. Alternatively, the plurality of polished layers may be characterized in that at least 10 of the plurality of polished layers have a variation of less than 0.02 g / cm³ among the at least 10 polished layers. 3 Or less than 3% of the total weight. Attached Figure Description

[0008] Figure 1a and Figure 1b This is a graph showing the specific gravity of polished layers in a series of polished layers cut from a cured cast block of various formulations.

[0009] Figure 2a and Figure 2b These are scanning electron microscope (SEM) images of a polished layer from the prior art and an exemplary polished layer as disclosed herein. Detailed Implementation

[0010] The inventors of this invention have discovered a method that enables the efficient manufacture of polishing pads comprising polishing layers having consistent properties, such as specific gravity and pore size distribution. Furthermore, this method enables the formation of polishing layers with relatively low specific gravity and / or unimodal pore size distribution. The method involves reacting a specific curing agent blend with a prepolymer in the presence of pre-expanded polymer microspheres. The prepolymer and curing agent react to form a polymer matrix. The curing agent blend facilitates further overexpansion of the polymer microspheres to achieve an unexpectedly low specific gravity. The method includes casting a mixture of the prepolymer, pre-expanded polymer microspheres, and curing agent blend into a mold, curing the composition in the mold to form a porous polymer block, and cutting the porous polymer block into a series of polishing layers. The series of polishing layers is characterized in that portions of the series of polishing layers cut from the center of the block have a specific gravity more than 5% lower than polishing layers cut from the edges of the block. Alternatively or alternatively, the polished layers in this series may be characterized in that a portion of the series has a specific gravity variation of less than 0.03, less than 0.02, or less than 0.01 g / cm³. Alternatively or additionally, the polished layers in this series may be characterized in that a portion of the series has a specific gravity variation of less than 3%.

[0011] As used in this article, specific gravity is the ratio of the weight to the volume of a sample.

[0012] The polishing pad disclosed herein has a polishing layer formed by reacting an isocyanate-terminated prepolymer with a curing agent blend in the presence of pre-expanded polymer microspheres. The curing agent blend comprises one or more monoaromatic polyamines and one or more polyamines having two or more aromatic rings. The polishing pad can be characterized by one or more of the following: a unimodal size distribution and a specific gravity of less than 0.70 g / cm³; a ratio of shear loss modulus (G”) at 104 °C to shear loss modulus (G”) at 150 °C of at least 5; and a specific gravity of the polishing layer less than or equal to 95% of the calculated specific gravity of the isocyanate-terminated oligomer or polymer, the curing agent blend, and the pre-expanded fluid-filled polymer microspheres.

[0013] Without being bound by theory, it is believed that the exothermic reaction between the curing agent system and the isocyanate-terminated prepolymer can facilitate further expansion of the polymer microspheres. As indicated by the greater decrease in shear loss modulus at higher temperatures, the presence of the curing agent blend can delay polymer solidification. This solidification, while still substantially hardening, effectively prevents further expansion of the polymer microspheres, thus avoiding pore collapse or destruction caused by further expansion. In this method, desired low specific gravity, unimodal pore size distribution, or both, can be obtained in formulations without containing unexpanded polymer microspheres.

[0014] The inventors of this invention have discovered that polished layers with a shear loss modulus (G”) (measured by dynamic mechanical analysis (e.g., according to ASTM D5279-08(2008)) at or slightly above the curing temperature to the shear loss modulus G” at 150°C, having a ratio greater than 5:1, greater than 5.5:1, greater than 7:1, greater than 9:1, greater than 10:1, greater than 12:1, or greater than 15:1, can have super-expanded polymer microspheres as indicated by a lower specific gravity in the final pad. The ratio of the shear loss modulus (G”) (measured by dynamic mechanical analysis (e.g., according to ASTM D5279-08(2008)) at or slightly above the curing temperature to the shear loss modulus G” at 150°C can also be, for example, less than 30:1 or less than 25:1. In addition to their elastic properties, these polishing layers also have viscous properties that allow the microspheres to expand more during casting and wet the polishing pad during polishing.

[0015] The pads disclosed herein can have an actual specific gravity of the polishing layer that is 97%, 96%, 95%, 94%, 93%, 92%, 91%, or 90% smaller than the calculated average specific gravity of the polishing layer. Simultaneously, the actual specific gravity of the polishing layer can also be, for example, at least 50%, at least 60%, at least 70%, or at least 75% of the calculated specific gravity of the polishing layer. The actual specific gravity can be determined by weighing and determining the volume of the sample and dividing the sample weight by the volume. The calculated specific gravity is (total weight of the prepolymer plus one or more curing agents plus pre-expanded polymer microspheres) divided by (prepolymer weight ÷ prepolymer specific gravity) plus (weight of polymer microspheres ÷ specific gravity of pre-expanded polymer microspheres) plus the sum of (weight of the curing agent ÷ specific gravity of the curing agent) for each curing agent. Although some further expansion occurs for most systems, the curing agent blends disclosed herein exhibit more expansion relative to single curing agent systems, resulting in over-expanded polymer microspheres.

[0016] The prepolymer contains at least two isocyanate groups for reaction with the curing agent. In other words, each prepolymer has at least two isocyanate end groups. The isocyanate groups can be terminal groups on the prepolymer. For example, if the prepolymer is a straight-chain prepolymer without branching or isocyanate side groups, two terminal isocyanate end groups may be present.

[0017] The prepolymer system may contain one prepolymer or a mixture of two or more prepolymers. The weight percentage range of unreacted isocyanate groups (NCO) can be adjusted by blending the prepolymer with its prepolymer polyol. The prepolymer system may optionally contain substances with lower molecular weights, such as monomers, dimers, etc.

[0018] Prepolymers can be formed from polyfunctional aromatic isocyanates (e.g., aromatic polyisocyanates) and prepolymer polyols.

[0019] For the purposes of this specification, the term prepolymer polyol includes diol, polyol, polyol-diol, copolymers thereof, and mixtures thereof. Examples of prepolymer polyols include polyether polyols such as poly(oxytetramethylene) glycol, poly(oxypropylene) glycol, and mixtures thereof, polycarbonate polyols, polyester polyols, polycaprolactone polyols, and mixtures thereof. The aforementioned polyols may be mixed with low molecular weight polyols such as 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, tripropylene glycol, and mixtures thereof. Prepolymer polyols may be selected, for example, from the group consisting of: polytetramethylene ether glycol [PTMEG], polyethylene glycol [PEG] (also known as polyethylene oxide [PEO]), polypropylene ether glycol [PPG] (also known as polypropylene oxide [PPO]), ester polyols (such as ethylene glycol adipate or butylene adipate), copolymers thereof, and mixtures thereof.

[0020] Examples of polyfunctional aromatic isocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4′-diphenylmethane diisocyanate, dicyclohexylmethane 4,4′-diisocyanate, naphthalene-1,5-diisocyanate, benzyltoluidine diisocyanate, p-phenylene diisocyanate, diphenylmethylene diisocyanate, mixtures thereof, and their isomers. Polyfunctional aromatic isocyanates may contain less than 20% by weight of aliphatic isocyanates, such as dicyclohexylmethane 4,4′-diisocyanate, isophorone diisocyanate, and cyclohexane diisocyanate. Polyfunctional aromatic isocyanates may contain less than 15% or less than 12% by weight of aliphatic isocyanates.

[0021] If the prepolymer polyol includes PTMEG, its copolymers, or mixtures thereof (e.g., a mixture of PTMEG with PPG or PEG), the isocyanate-terminated reaction product may have unreacted NCO in the following weight percentage ranges based on the total weight of the prepolymer polyol: 4.0 to 30.0, or 6.0 to 10.0 weight percentage. Specific examples of PTMEG family polyols are as follows: from LyondellBasell... 2900, 2000, 1000, 650; PTMEG polyols 220, 650, 1000, 1400, 1800, 2000, and 3000 available from Gantrade; and from BASF. 650, 1000, 2000, and low molecular weight substances such as 1,2-butanediol, 1,3-butanediol, and 1,4-butanediol. If the prepolymer polyol is PPG / PO, its copolymer, or a mixture thereof, the isocyanate-terminated reaction product can have unreacted NCO in the following weight percentage ranges: 4.0 to 30.0, or 6.0 to 10.0 weight percentages. Specific examples of PPG polyols are as follows: from Covestro... PPG-425, 725, 1000, 1025, 2000, 2025, 3025, and 4000; from Dow Chemical Company. 1010L, 2000L and P400; 1110BD Polyols 12200, 8200, 6300, 4200, and 2200 are both product lines from Covestro. If the prepolymer polyol is an ester, its copolymer, or a mixture thereof, the isocyanate-terminated reaction product can have an unreacted NCO content ranging from 6.5 to 13.0% by weight. Specific examples of ester polyols include: Millester 1, 11, 2, 23, 132, 231, 272, 4, 5, 510, 51, 7, 8, 9, 10, 16, and 253 from Polyurethane Specialties Company, Inc.; and from Covestro. 1700, 1800, 2000, 2001KS, 2001K2, 2500, 2501, 2505, 2601, PE65B; Rucoflex S-1021-70, S-1043-46, S-1043-55 from Covestro.

[0022] Preferably, the prepolymer reaction product has 2.0 to 15.0 wt%, 5 to 13 wt%, 7 to 11 wt%, or 8 to 10 wt% unreacted NCO. Examples of suitable prepolymers within this range of unreacted NCO include those manufactured by COIM USA, Inc. Prepolymers PST-80A, PST-85A, PST-90A, PST-95A, PET-85A, PET-90A, PET-91A, PET-93A, PET-95A, PET-60D, PET-70D, PET-75D, PHP-80A, PHP-85A, PHP-60D, PHP-75D, PHP-80D, PPT-80A, PPT-90A, PPT-95A, PPT-65D, PPT-75D, PCM-95A, PCM-75D, APC-504, APC-722, and API-470, as well as those manufactured by Lanxess. Prepolymers LFG740D, LF700D, LF750D, LF751D, LF753D, L325, LF600D, LFG963A, and LF950A. Additionally, blends of other prepolymers besides those listed above can be used to achieve an appropriate percentage of unreacted NCO levels as the result of blending. Many of the prepolymers listed above include LFG740D, LF700D, LF750D, LF751D, LF753D, LF600D, LFG963A, LF950A, PST-80A, PST-85A, PST-90A, PST-95A, PET-85A, PET-90A, PET-91A, PET-93A, PET-95A, PET-60D, PET-70D, PET-75D, and PHP-80A. PHP-85A, PHP-60D, PHP-75D, PHP-80D, PPT-80A, PPT-90A, PPT-95A, PPT-65D, PPT-75D, PCM-95A, and PCM-75D are low-free isocyanate prepolymers with less than 0.1% by weight of free toluene diisocyanate (TDI) monomer and a more consistent prepolymer molecular weight distribution than conventional prepolymers, thus contributing to the formation of polishing pads with excellent polishing characteristics. This improved prepolymer molecular weight consistency and low-free isocyanate monomer result in a more regular polymer structure and contribute to improved polishing pad consistency. For most prepolymers, the low-free isocyanate monomer is preferably less than 0.5% by weight. Furthermore, “conventional” prepolymers, typically with higher levels of reactivity (i.e., more than one polyol is end-capped with diisocyanate at each end) and higher levels of free toluene diisocyanate, should produce similar results. In addition, low molecular weight polyol additives such as diethylene glycol, butanediol and tripropylene glycol help control the weight percentage of unreacted NCO in the prepolymer reaction products.

[0023] As an example, the prepolymer can be the reaction product of 4,4′-diphenylmethane diisocyanate (MDI) and polytetramethylene glycol with a diol. Most preferably, the diol is 1,4-butanediol (BDO). Preferably, the prepolymer reaction product has 6 to 13 wt.% unreacted NCO. Examples of suitable polymers having this range of unreacted NCO include: Imuthane 27-85A, 27-90A, 27-95A, 27-52D, 27-58D from Coeur Inc. and from Anderson Development Company. IE-75AP, IE80AP, IE90AP, IE98AP, IE110AP prepolymers.

[0024] The curing agent blend comprises one or more monoaromatic amine curing agents and one or more polyamine curing agents having two or more aromatic rings. The polyamine may be a diamine. The monoaromatic polyamine curing agent may include, for example, one or more alkylthiotoluene diamines (such as dimethylthiotoluene diamine [DMTDA], diethylthiotoluene diamine [DETDA], monomethylthiotoluene diamine, monoethylthiotoluene diamine, or combinations of two or more thereof); alkylchlorotoluene diamines (such as dimethylchlorotoluene diamine, diethylchlorotoluene diamine, 4-chloro-3,5-diethyltoluene-2,6-diamine); and trimethylene glycol di- p-Aminobenzoate; polytetramethylene oxide di-p-aminobenzoate; polytetramethylene oxide mono-p-aminobenzoate; polypropylene oxide di-p-aminobenzoate; polypropylene oxide mono-p-aminobenzoate; isobutyl 4-chloro-3,5-diaminobenzoate; 5-tert-butyl-2,4- and 3-tert-butyl-2,6-toluenediamine; 5-tert-pentyl-2,4- and 3-tert-pentyl-2,6-toluenediamine; and chlorotoluenediamine. The polyamine curing agent having two or more aromatic rings may include one or more of the following, for example: 4,4′-methylene-bis-o-chloroaniline [MOCA], 4,4′-methylene-bis-(3-chloro-2,6-diethylaniline) [MCDEA]; 1,2-bis(2-aminophenylthio)ethane; 4,4′-methylene-bis-aniline; methylene-bis-methylo-o-aminobenzoate [MBNA].

[0025] Polyamine curing agents with two or more aromatic rings (e.g., MOCA) and monoaromatic polyamine curing agents (e.g., Ethacure) TM The molar ratio of 300 can be, for example, 20:80 to 80:20, 25:75 to 75:25, 30:70 to 70:30, 35:65 to 65:35, 40:60 to 60:40, 45:55 to 55:45, or about 50:50.

[0026] The ratio of prepolymer to curing agent can be determined based on stoichiometry. As used herein, the “stoichiometry” of the reaction mixture refers to the molar equivalent of (free OH + free NH2 groups) in the curing agent relative to the free NCO groups in the prepolymer (e.g., 100 × (total moles of amine and OH groups in the curing agent blend / total moles of NCO groups in the prepolymer or prepolymer blend)). Stoichiometry can be, for example, in the range of 80% to 120%, preferably 87% to 105%.

[0027] Following the polymerization reaction of the curing agent and the isocyanate-functionalized prepolymer, the resulting polymer comprises a hard phase and a soft phase (or hard segments and soft segments). The hard phase can be arranged and stacked in an ordered and / or random manner to form hard segment domains.

[0028] Pre-expanded polymer microspheres are filled with a fluid, which can be a gas, a liquid, or a combination of gas and liquid. If the fluid is a liquid, water is preferred, such as distilled water containing only incidental impurities. For the purposes of this application, the term microsphere refers to a shell having a less-than-perfect spherical shape; for example, when cut open and observed with SEM, these shells have a shape that appears hemispherical. If the fluid is a gas, air, nitrogen, argon, carbon dioxide, or a combination thereof are preferred. For some microspheres, the gas can be an organic gas, such as isobutane. Preferably, the fluid is isobutane, isopentane, or a combination of isobutane and isopentane. Isobutane trapped in polymer microspheres is gaseous at room temperature (25°C) and above, depending on the internal pressure within the polymer shell. Isopentane trapped in polymer microspheres is a combination of liquid and gas at room temperature. At temperatures of about 30°C and higher, isopentane becomes gaseous—depending on the internal pressure within the polymer shell. The polymer shell contains the liquid; and typically, the polymer shell contains the gas under pressure. Specific examples of polymer shells include polyacrylonitrile / methacrylonitrile shells and poly(vinylidene chloride) / polyacrylonitrile shells, such as poly(acrylonitrile-co-vinylidene chloride-co-methyl methacrylate) shells. Furthermore, these shells can incorporate inorganic particles, such as silicates, calcium-containing, or magnesium-containing particles. These particles facilitate the separation of polymer microspheres. The pre-expanded polymer microspheres are expanded to their nominal diameter before being combined with the prepolymer. Typical nominal diameters range from 10 to 60, 15 to 50, or 17 to 45 micrometers. For example, the nominal diameter could be 20 micrometers or 40 micrometers. Pre-expanded polymer microspheres can grow to a final average diameter of 20 to 150 micrometers by 10 to 60 percent. However, the inventors have found that actual expansion within the polymer matrix formed by the reaction of the prepolymer with the curing agent can be limited by the solidification of the polymer matrix. For example, using a single curing agent (a monoaromatic amine curing agent or a polyaromatic amine curing agent), further expansion is limited or partial pore shrinkage may occur. However, the inventors discovered that by using a blend of phenyl diamine curing agent and polyaromatic diamine curing agent, the matrix restricts the expansion less while avoiding pore collapse or rupture, thereby enabling a lower specific gravity.

[0029] Pre-expanded polymer microspheres can be added to the mixture in amounts ranging from 0.5, 0.75, 1, 1.25, 1.5, 1.75, or 2% by weight of the prepolymer, curing agent, and pre-expanded polymer microspheres. The amount of pre-expanded polymer microspheres can also be up to 7, 5, 4.5, 4, 3.5, or 3.0% by weight of the prepolymer, curing agent, and pre-expanded polymer microspheres. For convenience, the pre-expanded polymer microspheres can be pre-blended with the prepolymer before adding the curing agent.

[0030] Pre-expanded polymer microspheres can have a specific gravity of 0.01 to 0.2, 0.02 to 0.15, 0.05 to 0.1, or 0.070 to 0.096 g / cm³. Examples of suitable pre-expanded polymer microspheres include those manufactured by Nouryon. 551DE40d42, 551DE20d60, 461DE20d70, 461DE40d60, 461DET80d25, 092DET100d25, 920DE40d30, 920DET40d25 and 920DE80d30, and manufactured by Matsumoto Yushi Seiyaku Co., Ltd. FN-80SDE, F-65DE, F-80DE, FN-100SSDE, and F-190DE.

[0031] The polished layer disclosed herein may optionally have a molecular weight less than 1.0, or less than or equal to 0.99, or less than or equal to 0.98, or less than or equal to 0.97, or less than or equal to 0.96, or less than or equal to 0.95, or less than or equal to 0.94, or less than or equal to 0.93, or less than or equal to 0.92, or less than or equal to 0.91, or less than or equal to 0.90, or less than or equal to 0.89, or less than or equal to 0.88, or less than or equal to 0. 0.87, or less than or equal to 0.86, or less than or equal to 0.85, or less than or equal to 0.84, or less than or equal to 0.83, or less than or equal to 0.82, or less than or equal to 0.81, or less than or equal to 0.80, or less than or equal to 0.79, or less than or equal to 0.78, or less than or equal to 0.77, or less than or equal to 0.76, or less than or equal to 0.75, or less than or equal to 0.74, or less than or equal to 0.73 g / cm³ 3The proportion of. Advantageously, the polished layer disclosed herein may optionally have a specific gravity of less than or equal to 0.72, or less than or equal to 0.71, or less than or equal to 0.70, or less than or equal to 0.69, or less than or equal to 0.68, or less than or equal to 0.67, or less than or equal to 0.66, or less than or equal to 0.65, or less than or equal to 0.64, or less than or equal to 0.63, or less than or equal to 0.62, or less than or equal to 0.61, or less than or equal to 0.60, or less than or equal to 0.59, or less than or equal to 0.58, or less than or equal to 0.57, or less than or equal to 0.56, or less than or equal to 0.55, or less than or equal to 0.54, or less than or equal to 0.53, or less than or equal to 0.52, or less than or equal to 0.51, or less than or equal to 0.50, or less than or equal to 0.49, or less than or equal to 0.48 g / cm3. Specific gravity can typically be at least 0.3, at least 0.4, or at least 0.45 g / cm³. Specific gravity, as used herein, is the weight / volume of the sample and can be determined, for example, as described in ASTM D1622-08 (2008). Such polished layers can also have a unimodal pore size distribution.

[0032] The pore size in the cured polished layer can range from about 5 micrometers to about 80 micrometers, with an average pore size of at least 23 micrometers, as measured, when starting with pre-expanded porous microspheres having a nominal size of 20 micrometers. When the pre-expanded polymer microspheres have a nominal size of 40 micrometers, the average pore size of the cured polished layer can be at least 45 micrometers. The average pore size can be at least 15%, at least 16%, at least 17%, at least 18%, at least 19%, or at least 20% larger than the nominal size of the pre-expanded polymer microspheres.

[0033] The prepolymer, curing agent blend, and pre-expanded polymer microspheres can be combined, mixed, and then poured into a mold. Once the mixing reaction begins, it is important to pour the mixture into the mold quickly. After the mold is filled to the appropriate height, the mixture in the mold is heated (e.g., cured in an oven). The height of the mixture in the mold can be at least 2.5 cm, at least 3.5 cm, at least 5 cm, at least 6.5 cm, at least 7.5 cm, at least 9.0 cm, at least 10.0 cm, at least 11.5 cm, at least 12.5 cm, at least 13.0 cm, at least 13.5 cm, at least 14.0 cm, at least 14.5 cm, or at least 15.0 cm and up to a desired height, such as 30, 25, or 20 cm. The curing temperature is set to at least the minimum curing temperature required for the prepolymer and curing agent. The curing temperature can be, for example, about 100°C to 120°C, or 102°C to 110°C, or 104°C. The curing time can be from 5 to 20 hours, or 10-15 hours. The mold can have dimensions (width and length, or diameter) to provide a polished layer of the desired size to produce cured preparation blocks or biscuits. The width, length, and diameter of the mold can be large enough to allow multiple blocks or biscuits to be cut from the cured preparation.

[0034] The cured formulation is removed from the mold, and the block or cake is sheeted from its original thickness (e.g., 5 cm) to the desired polished layer thickness (e.g., 0.10 to 0.35, or 0.125 to 0.20 cm). The inventors have found that this method enables the production of multiple polished layers with uniform porosity from top to bottom and a lower overall specific gravity compared to when a single polished layer is formed directly from the mixture. Polished layers cut from the top and bottom of the block or cake may not meet the desired properties. Therefore, if the sheet is made from a block or cake of original thickness, the first 3-5 sheets and the last 3-5 sheets may not exhibit the desired uniformity and low specific gravity. However, it is possible to form ten or more, twelve or more, or fifteen or more polished layers with specific gravities varying by less than ±0.1, less than ±0.05, less than ±0.03, less than ±0.02, or less than ±0.01 g / cm³ from a single block or cake. The ten (or 12 or 15) or more polished layers have a specific gravity at least 0.04 g / cm³ lower than that of polished layers cut from the top or bottom edge of the same block. A series of polished layers cut from the center of the block can have a specific gravity at least 5%, 6%, 7%, 8%, 9%, 10%, 11%, or 12% lower than that of polished layers cut from the edge of the block (or at least 10%, 12%, 15%, 17%, or 20% lower than that of the center of the block). Furthermore, this method enables the attainment of a lower specific gravity than that achievable by casting the same formulation directly as individual polished layers. For example, the specific gravity of the polished layer may be at least 0.02, at least 0.03, at least 0.04, at least 0.05, at least 0.06, at least 0.07, at least 0.08, at least 0.09, at least 0.10, at least 0.11, or at least 0.12 g / cm3 less than that of a polished layer cast as a single polished layer (rather than cast as a block and cut from the block).

[0035] Polishing with the same slurry, the same prepolymer, the same pre-expanded polymer microspheres, the same weight percentage of pre-expanded polymer microspheres, the same stoichiometry, the same processing conditions, the same grooves, the same construction, the same pad thickness, the same specific gravity, the same polishing machine, the same dressing disc, and the same polishing scheme, as disclosed herein, shows an improvement in metal and oxide removal rates of at least 10% compared to similar pads made with a single aromatic polyamine curing agent. Polishing with the same slurry, as disclosed herein, shows an improvement in tungsten removal rates of at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, and at least 40% compared to similar pads having a polishing layer formed with a single aromatic polyamine curing agent. Polishing with the same slurry, as disclosed herein, shows an improvement in copper removal rates of at least 10%, at least 15%, at least 20%, and at least 25% compared to similar pads having a polishing layer formed with a single aromatic polyamine curing agent. Polishing with the same slurry, such as the pads disclosed herein, showed an improvement in oxide removal rate of at least 10% and at least 15% compared to similar pads having a polishing layer made with a single aromatic polyamine curing agent.

[0036] Example

[0037] Materials used:

[0038] L325 is an Adiprene from Lanxess. TM Prepolymer L325.

[0039] The LFG740D is an Adiprene from Lanxess. TM Prepolymer LFG740D.

[0040] The LF750D is an Adiprene from Lanxess. TM Prepolymer LF750D.

[0041] MOCA is 4,4′-methylene-bis-(2-chloroaniline).

[0042] Ethacure TM 300 is a mixture of dimethylthiotoluene diamine / monomethylthiotoluene diamine from Albemarle Co.

[0043] The pre-expanded polymer microspheres are pre-expanded poly(acrylonitrile-co-vinylidene chloride-co-methyl methacrylate) microspheres with an average diameter of about 20 μm.

[0044] Example 1

[0045] A polyisocyanate prepolymer was blended with pre-expanded polymer microspheres having a nominal particle size of 20 micrometers to form a premix. The premix was heated to 52°C to ensure sufficient flowability. A preheat curing agent (MOCA) was used at 115°C and Ethacure... TM (300 is 46°C). The curing agent is then mixed with the premix in a high-shear mixer and poured directly from the mixer head into a flat-bottomed, 86.36 cm (34") diameter polytetrafluoroethylene (PTFE-coated) circular mold to give a total pour thickness of about 6 to 15 cm over a period of about 2 to 5 minutes. The mold is preheated to about 107°C. About 15 minutes after pouring is complete, the mold is placed in a curing oven. The composition is then heated in the oven using the following cycle: from ambient temperature to a set point of 104°C for 30 minutes, then held at 104°C for 15.5 hours, and then cooled from 104°C to 21°C for 2 hours.

[0046] The cured polymer block is then removed from the mold and cut using a fixed blade at a temperature of 70°C to 90°C into approximately thirty-five individual sheets of 2.032 mm (80 mils) thickness, or forty-five individual sheets of 1.651 mm (65 mils) thickness, or fifty-five individual sheets of 1.27 mm (50 mils) thickness, wherein the cured polymer block is approximately 7.62 cm thick (3"). Horizontal cutting is performed on the block such that 35, 45, or 55 sheets are gradually cut from the top of each block according to its thickness.

[0047] The specific gravity of each cut sheet, as determined by ASTM D1622-08 (2008), is measured on the entire sheet, by dividing the total weight of the cut sheet by its total volume. The sheet volume is determined by measuring its diameter and thickness. Specific gravity data is reported on... Figure 1a The table shows the specific gravity data for the prepolymer L325 blend along with various curing agents in the following order: sheet from the top edge of each block, sheet from the middle of the block, and sheet from the bottom edge of each block. (Each point represents the specific gravity of a sheet, and these sheets are arranged from top edge to bottom edge, corresponding to points from left to right). Figure 1b The table shows the specific gravity data for sheets of prepolymer blends of LFG740D and LF750D at a 4:1 w / w ratio, along with various curing agents, from the top edge to the bottom edge of each block. It can be seen that the sheets obtained from the top and bottom edges have a higher specific gravity than those from the middle, and the middle sheets made with the blended curing agents have a higher specific gravity than those made with only a single curing agent (such as MOCA or Ethacure). TM Sheets made with 300 curing agent have a lower specific gravity.

[0048] In contrast, when MOCA was the only curing agent, the specific gravity curve of the cut sheet did not show significant peaks of higher specific gravity at the top and bottom edges.

[0049] For further comparison, when the prepolymer is combined with polymer microspheres and Ethacure TM When the formulation of the blend of 300 and MOCA curing agent is directly cast as a single polished layer with a thickness of 2.032 mm (80 mils), the polished layer has a content of 0.76 g / cm³. 3 The specific gravity was 0.70 g / cm³ when using the same formulation, but when cast as a block and then cut, the specific gravity was 0.70 g / cm³. 3 The proportion of.

[0050] Example 2

[0051] The polished layer is made using the formulations described in Table 1, essentially as in Example 1. The actual specific gravities reported in Table 1 do not include those shown in Table 1. Figure 1a and Figure 1b The sheet material in the peak region shown refers to the thin polymer layer or sheet material cut from the region near the top and bottom edges. The shear loss modulus (measured as G”) was measured by shear dynamic mechanical analysis (DMA), ASTM D5279-08 (2008). All shear loss modulus values ​​(G”) were obtained on an Ares G2 instrument (supplied by TA Instruments) using a sample with dimensions of 36 mm × 6.5 mm and a 20 mm gap between the clamps. The instrument setup was as follows:

[0052] Nitrogen atmosphere

[0053] Starting temperature -100℃, inherent setpoint: Off

[0054] Soaking time: 20.0s, waiting temperature: open

[0055] Heating / cooling rate: 3.0℃ / min

[0056] Soaking time after temperature rise and fall: 0.0s

[0057] Estimated completion time: 1 hour 23 minutes 0 seconds

[0058] Sampling interval 10s / pt

[0059] Strain % 0.2%

[0060] single point

[0061] Angular frequency 10 rad / s

[0062] Data collection mode: Relevance is selected.

[0063] Delay loop 0.5

[0064] Delay time: 3.0s

[0065] Sampling loop 2 half-cycles

[0066] Correlation-based frequency: Off; Save waveform (dot display): Off; Save image: Off; Iterative strain: Off

[0067] Adjustment: Off. Use additional harmonics: Off.

[0068] Superimposed stable shear rate: Maintain axial force during acquisition: On

[0069] Enable: Disable Enable: Disable Enable: Disable

[0070] The ratio of G” at 104°C to G” at 150°C is reported in Table 1. The specific gravity was calculated as described above. The results are shown in Table 1.

[0071]

[0072] Example 3

[0073] The polished layer uses a blend of LFG740D and LF750D in a weight ratio of 4:1 as a prepolymer, along with MOCA and Ethacure. TM A blend of 300% as a curing agent (at 2:3 and 1:1 molar ratios) and stoichiometric 87%, together with pre-expanded polymer microspheres of varying loadings having a nominal size of 20 micrometers, was prepared substantially as described in Example 1. Specific gravity was calculated and measured.

[0074] The results are shown in Table 2.

[0075] Table 2

[0076]

[0077] Example 4

[0078] The pore size and pore size distribution of certain samples using L325 as a prepolymer were examined. MOCA / Ethacure was used. TM A 50 / 50 molar ratio blend of 300 provides an average pore size of 24.5 micrometers (approximately 22.5% higher than the nominal pore size of pre-expanded polymer microspheres), compared to using Ethacure alone. TMThis yielded an average pore size of 22.7 micrometers (an increase of approximately 13.5% over the nominal pore size of the pre-expanded polymer microspheres).

[0079] Example 5

[0080] A scanning electron microscope (SEM) image of a polished layer made from a combination of pre-expanded and unexpanded microspheres, as disclosed in patent number 9,586,304, is shown in Figure 2a (Prior Art). An SEM image of an exemplary polished layer disclosed herein is also shown. Figure 2b middle.

[0081] Example 6

[0082] Use a polishing layer on Suba TM Polishing pads were prepared on IV or SP2310 sub-pads. The polishing layer of all pad examples was finished with overlapping annular (1010) and radial (R32) grooves (1010+R32), and annular (K7D) grooves. The annular 1010 grooves have a width of 0.46 mm (18 mils), a depth of 0.76 mm (30 mils), and a pitch of 3.05 mm (120 mils). The R-32 radial grooves are 32 evenly spaced radial grooves with a width of 0.76 mm (30 mils) and a depth of 0.81 mm (32 mils). The annular (K7D) grooves have a width of 0.36 mm (14 mils), a depth of 1.02 mm (40 mils), and a pitch of 1.78 mm (70 mils). The annular (K7) groove has a width of 0.46 mm (18 mils), a depth of 0.76 mm (30 mils), and a pitch of 1.78 mm (70 mils).

[0083] As described above, it is made by blending with pre-expanded polymer microspheres and Ethacure. TM A contrast pad made from a polishing layer formed from the L325 prepolymer of the 300 reaction as described herein showed a polishing speed of 2285 Å / min when polishing tungsten with a low-selectivity slurry. The tungsten removal rate. Ethacure, which is composed of pre-expanded polymer microspheres blended in a 1:1 molar ratio, [is used in this context]. TM The polishing layer pad made of L325 prepolymer reacted with 300 / MOCA curing agent showed, under the same slurry and conditions, The tungsten removal rate was increased by 12%. For the blended curing agent, the same type of pad showed a 6% increase in copper removal rate.

[0084] As described above, a contrast pad made from a polishing layer formed as described herein from an L325 prepolymer blended with pre-expanded polymer microspheres and reacted with MOCA showed performance in polishing tungsten with a highly selective slurry. The tungsten removal rate. Ethacure, which is composed of pre-expanded polymer microspheres blended in a 1:1 molar ratio, [is used in this context]. TM The polishing layer pad made of L325 prepolymer reacted with 300 / MOCA curing agent showed, under the same slurry and conditions, The tungsten removal rate was increased by 12%.

[0085] This disclosure further covers the following aspects.

[0086] Aspect 1: A method for forming a plurality of polishing layers for a chemical mechanical polishing pad, the method comprising:

[0087] A mold is filled with a mixture comprising an isocyanate-functionalized prepolymer, pre-expanded fluid-filled polymer microspheres, and a curing agent blend, wherein the curing agent blend comprises a monoaromatic polyamine curing agent and a polyamine curing agent having two or more aromatic rings, wherein the mixture is characterized by heat released from the reaction between the isocyanate-functionalized prepolymer and the curing agent.

[0088] The mixture is cured at a curing temperature in a filled mold to form a polymer block comprising a cured polymer matrix and pores formed by further expansion of pre-expanded fluid-filled polymer microspheres, the further expansion being caused by heat from the curing and heat released from the reaction, wherein the mixture remains soft in the central portion of the block for a period of time to allow for the further expansion; and

[0089] The polymer block is cut to form a plurality of polished layers, wherein the portion of the plurality of polished layers cut from the center of the block has a specific gravity that is more than 5%, preferably more than 7%, smaller than that of the polished layers cut from the edge of the block.

[0090] Aspect 2: The method as described in aspect 1, wherein the portions of the plurality of polished layers cut from a series of central portions have a specific gravity variation of less than 0.03, preferably less than 0.02, more preferably less than 0.01 g / cm3.

[0091] Aspect 3: A method for forming a plurality of polishing layers for a chemical mechanical polishing pad, the method comprising:

[0092] A mold is filled with a mixture comprising an isocyanate-functionalized prepolymer, pre-expanded fluid-filled polymer microspheres, and a curing agent blend, wherein the curing agent blend comprises a monoaromatic polyamine curing agent and a polyamine curing agent having two or more aromatic rings, wherein the mixture is characterized by heat released from the reaction between the isocyanate-functionalized prepolymer and the curing agent.

[0093] The mixture is cured at a curing temperature in a filled mold to form a polymer block comprising a cured polymer matrix and pores formed by further expansion of polymer microspheres filled by the pre-expanded fluid, the further expansion being caused by heat from the curing and heat released from the reaction, wherein the mixture remains soft in the central portion of the block for a period of time to allow the further expansion to take place;

[0094] The polymer block is cut to form a plurality of polished layers, wherein at least 10 of the plurality of polished layers have a variation of less than 0.03, preferably less than 0.02, and more preferably less than 0.01 g / cm³ among the at least 10 polished layers. 3 or less than 3% of the total weight.

[0095] Aspect 4: The method as described in any of the preceding aspects, wherein the cured mixture comprises polyurethane soft segments and polyurea-polyurethane hard segments.

[0096] Aspect 5: The method as described in any of the preceding aspects, wherein the molar ratio of the monoaromatic polyamine curing agent to the polyamine curing agent having two or more aromatic rings is 20:80 to 80:20; preferably 25:75 to 75:25; more preferably 30:70 to 70:30; even more preferably 35:65 to 65:35; or even more preferably 40:60 to 60:40.

[0097] Aspect 6: The method of any one of the preceding aspects, wherein the monoaromatic polyamine curing agent comprises dimethylthiotoluene diamine, monomethylthiotoluene diamine, or both.

[0098] Aspect 7: The method of any of the preceding aspects, wherein the polyamine curing agent having two or more aromatic rings comprises 4,4′-methylene-bis-o-chloroaniline; 4,4′-methylene-bis-(3-chloro-2,6-diethylaniline); or both.

[0099] Aspect 8: The method of any one of the preceding aspects, wherein the isocyanate-functionalized prepolymer comprises polyether, polyester, polyethylene glycol, polypropylene glycol, polycaprolactone, polycarbonate, or a combination thereof.

[0100] Aspect 9: The method as described in any of the preceding aspects, wherein the plurality of polished layers have a viscosity of less than 0.75, preferably less than 0.72, more preferably less than 0.70, and even more preferably less than 0.68 g / cm³. 3 The proportion of.

[0101] Aspect 10: The method of any of the preceding aspects, wherein the plurality of polished layers are characterized by a ratio of viscous modulus (G”) at 104°C to viscous modulus (G”) at 150°C being at least greater than 5.

[0102] Aspect 11: The method as described in any of the preceding aspects, wherein the proportion of the portion of the plurality of polished layers cut from the central portion of the block is less than or equal to 95% of the calculated proportion of the components of the mixture.

[0103] Aspect 12: The method as described in any of the preceding aspects, wherein the block has a thickness of at least 5 cm and a minimum dimension perpendicular to the thickness of at least 10 cm.

[0104] Aspect 13: The method as described in any of the preceding aspects, wherein the amount of the pre-expanded polymer microspheres in the mixture is 0.5 to 7.0, preferably 2 to 5, by weight based on the total weight of the prepolymer, curing agent and pre-expanded polymer microspheres.

[0105] All ranges disclosed herein include endpoints, and endpoints can be combined independently of each other (e.g., the range “up to 25 wt.%, or more specifically 5 wt.% to 20 wt.%” includes the endpoints and all intermediate values ​​within the range “5 wt.% to 25 wt.%”, etc.). Furthermore, the upper and lower limits can be combined to form ranges (e.g., “at least 1 or at least 2 weight percent” and “up to 10 or 5 weight percent” can be combined to form ranges “1 to 10 weight percent”, or “1 to 5 weight percent”, or “2 to 10 weight percent”, or “2 to 5 weight percent”).

[0106] This disclosure may alternatively include any suitable components disclosed herein, or consist of or substantially consist of any suitable components disclosed herein. This disclosure may additionally or alternatively be formulated to be free of, or substantially free of, any components, materials, ingredients, additives, or substances used in prior art compositions or otherwise not essential for achieving the function and / or objectives of this disclosure.

[0107] All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if any terminology in this application contradicts or conflicts with a terminology in an incorporated reference, the terminology derived from this application shall take precedence over the conflicting terminology derived from the incorporated reference.

[0108] Unless otherwise stated herein, all test standards are valid up to the filing date of this application or, if priority is claimed, the most recent standard valid up to the filing date of the earliest priority application in which the test standard appears.

Claims

1. A method for forming a plurality of polishing layers for a chemical mechanical polishing pad, the method comprising: A mold is filled with a mixture comprising an isocyanate-functionalized prepolymer, pre-expanded fluid-filled polymer microspheres, and a curing agent blend, wherein the curing agent blend comprises a monoaromatic polyamine curing agent and a polyamine curing agent having two or more aromatic rings, wherein the mixture is characterized by the heat released from the reaction between the isocyanate-functionalized prepolymer and the curing agent blend. The mixture is cured at a curing temperature in a filled mold to form a polymer block having a top edge, a bottom edge, and a center. The polymer block comprises a cured polymer matrix and super-expanded polymer microspheres formed by the expansion of the pre-expanded fluid-filled polymer microspheres, the expansion being caused by heat from the curing and heat released from the reaction between the isocyanate-functionalized prepolymer and the curing agent blend. The mixture remains soft in the central portion of the polymer block for a period of time to allow the pre-expanded fluid-filled polymer microspheres to expand. The mixture containing super-expanded microspheres solidifies to prevent further expansion and avoid the rupture or collapse of the super-expanded microspheres; and The polymer block is cut to form a plurality of polished layers comprising super-expanded microspheres, wherein the portion of the plurality of polished layers cut from the center portion of the polymer block has a specific gravity more than 5% smaller than that of the polished layers cut from the top and bottom edges of the polymer block, and the plurality of polished layers comprises at least ten polished layers.

2. The method as described in claim 1, wherein, The specific gravity of the portion of each of the plurality of polished layers cut from the center of the polymer block is no greater than 0.72 g / cm³. 3 .

3. The method as described in claim 1, wherein, The plurality of polishing layers are formed from portions cut from the center of the polymer block, exhibiting a variation of less than 0.02 g / cm. 3 A series of polished layers with a specific gravity.

4. The method of claim 1, wherein, The monoaromatic polyamine curing agent includes dimethylthiotoluenediamine, monomethylthiotoluenediamine, or both, and the polyamine curing agent having two or more aromatic rings includes 4,4′-methylene-bis-o-chloroaniline, 4,4′-methylene-bis-(3-chloro-2,6-diethylaniline), or both.

5. The method of claim 1, wherein, The molar ratio of the monoaromatic polyamine curing agent to the polyamine curing agent having two or more aromatic rings is from 25:75 to 75:

25.

6. The method of claim 1, wherein, The plurality of polished layers are characterized by the following: the ratio of the viscous modulus (G) at 104°C to the viscous modulus (G) at 150°C is at least greater than 5.

7. The method of claim 1, wherein, The proportion of the portion of the plurality of polished layers cut from the center of the polymer block is less than or equal to 95% of the calculated proportion of the mixture filled in the mold.

8. The method of claim 1, wherein, The polymer block has a thickness of at least 5 cm and a minimum dimension perpendicular to the thickness of at least 10 cm.

9. The method of claim 1, wherein, The amount of the pre-expanded polymer microspheres in the mixture is 0.5 to 7.0% by weight based on the total weight of the prepolymer, curing agent, and pre-expanded polymer microspheres.

10. A method for forming a plurality of polishing layers for a chemical mechanical polishing pad, the method comprising: A mold is filled with a mixture comprising an isocyanate-functionalized prepolymer, pre-expanded fluid-filled polymer microspheres, and a curing agent blend, wherein the curing agent blend comprises a monoaromatic polyamine curing agent and a polyamine curing agent having two or more aromatic rings, wherein the mixture is characterized by the heat released from the reaction between the isocyanate-functionalized prepolymer and the curing agent blend. The mixture is cured at a curing temperature in a filled mold to form a polymer block having a top edge, a bottom edge, and a center. The polymer block comprises a cured polymer matrix and super-expanded polymer microspheres formed by the expansion of the pre-expanded fluid-filled polymer microspheres, the expansion being caused by heat from the curing and heat released from the reaction between the isocyanate-functionalized prepolymer and the curing agent blend. The mixture remains soft in the central portion of the polymer block for a period of time to allow the pre-expanded fluid-filled polymer microspheres to expand. The mixture containing super-expanded microspheres solidifies to prevent further expansion and avoid the rupture or collapse of the super-expanded microspheres; and The polymer block is cut to form multiple polished layers comprising super-expanded microspheres, wherein at least 10 of the multiple polished layers, cut from the center between the top and bottom edges, have a variation of less than 0.02 g / cm² among the at least 10 polished layers. 3 Or less than 3% of the total weight.

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