Formulation for a highly porous chemical mechanical polishing pad with high hardness and CMP pads made therewith

Abstract

To provide chemical mechanical polishing layers or pads that are improved in hardness, porosity and removal rate performance without an undesirable increase in defectivity.SOLUTION: The invention provides CMP polishing pads or layers having an unfilled Shore D (2 second) hardness of 57-77 or a filled Shore D (2 second) hardness of 18-50, made from a two-component reaction mixture of (i) a liquid aromatic isocyanate component comprising one or more aromatic diisocyanates or a linear aromatic isocyanate-terminated urethane prepolymer having an unreacted isocyanate (NCO) concentration of 18 to 47 wt.%, based on the total solids weight of the aromatic isocyanate component, and (ii) a liquid polyol component, including one or more curatives selected from the group of amines having specific formulas (I) and (II).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a two-component polyurethane composition for producing a chemical mechanical planarization polishing (CMP) pad having an unfilled Shore D hardness (2 seconds) of 57 to 77 or a filled Shore D hardness (2 seconds) of 18 to 50, a CMP polishing pad produced therefrom, and a method for producing the same. More particularly, the present invention relates to a CMP polishing pad comprising a polyurethane foam reaction product of a two-component reaction mixture of a liquid aromatic diisocyanate component and a liquid polyol component, with a selective curing agent that is a hydroxyl-substituted aliphatic tertiary amine. [Background technology]

[0002] In the CMP process, a polishing pad is combined with a polishing solution, such as an abrasive-containing polishing slurry and / or abrasive-free reactive liquid, to remove excess material in a manner that planarizes or maintains the planarity of semiconductor, optical, or magnetic substrates. There is a continuing demand for CMP polishing pads with improved layer uniformity or planarization performance combined with high removal rates. Increasing the CMP removal rate reduces polishing time and polishing solution consumption. Therefore, CMP pads with higher removal rates are desirable because they reduce costs in device manufacturing. The removal rate, particularly for Cu CMP, is affected by the hardness and porosity of the pad material.

[0003] US Patent Application Publication No. 2019 / 0232460 discloses a polishing pad comprising a thermoplastic polyurethane. The thermoplastic polyurethane having a tertiary amine is a reaction product of a polyurethane reaction including at least a chain extender having a tertiary amine, and has a density of 1.0 g / cm. 3 It has a density of more than 10 ...

[0004] U.S. Patent No. 9,484,212 discloses a polishing layer having a composition that is the reaction product of components including a polyfunctional isocyanate and an amine-initiated polyol curing agent. The amine-initiated polyol curing agent contains at least one nitrogen atom per molecule and at least three hydroxyl groups per molecule. Because the polyol contains amine functionality that can perform the curing function, a separate curing agent or polyol is not used.

[0005] U.S. Patent No. 10,208,154 discloses a two-component composition for producing chemical mechanical polishing pads. The composition contains a liquid aromatic isocyanate component, a liquid polyol component having a polyether backbone and 5 to 7 hydroxyl groups per molecule, and a curing agent. The curing agent is one or more aromatic polyamines or aromatic diamines.

[0006] US Patent No. 9,156,127 discloses a polishing pad having a polishing layer comprising a thermosetting polyurethane foam having approximately spherical, interconnected cells with an average cell diameter of 35 to 200 μm.

[0007] There is a need for chemical mechanical polishing layers or pads with improved hardness, porosity, and removal rate performance without undesirable increased defectivity. The present disclosure meets this need by providing a composition for forming a polyurethane polishing layer by using a hydroxyl-substituted aliphatic tertiary amine as a curing agent to achieve a highly porous polishing pad with improved hardness and removal rate performance. Summary of the Invention

[0008] 1. According to the present invention, a reaction mixture for forming a chemical mechanical polishing (CMP polishing) layer, which is free of organic solvents, comprises: (i) a liquid aromatic isocyanate component, the liquid aromatic isocyanate component comprising one or more aromatic diisocyanates or a linear aromatic isocyanate-terminated urethane prepolymer having an unreacted isocyanate (NCO) concentration of 18 to 47 weight percent based on the total solids weight of the aromatic isocyanate component; (ii) a liquid polyol component; and (iii) one or more curing agents selected from the group of amines having formulas (I) and (II): [ka] wherein each R1 and R2 is independently C1-C6 alkyl, C1-C4 alkyl substituted with one or more C1-C4 alkyls or C1-C4 alkyl substituted with one or more halogens, -(CR5R6) p -S-(CR5R6) q -,or -(CR5R6) p -O-(CR5R6) q -; R3 is C1-C6 alkyl or C1-C4 alkyl substituted with one or more C1-C4 alkyl; each R4 is independently H or -R1-OH; each R5 and R6 is independently H or C1-C6 alkyl; each p and q is independently an integer from 1 to 5; n is in the range of 1 to 4, the reaction mixture comprises 55 to 75 wt% of hard segment material based on the total weight of the reaction mixture, and the curing agent (I) and / or (II) is in the range of 9 to 26.8 wt% based on the total weight of the reaction mixture, and the CMP polishing layer has an unfilled Shore D (2 sec) hardness of 57 to 77 or a filled Shore D (2 sec) hardness of 18 to 50, and a density of 0.43 to 0.78 g / mL. The polishing layer comprises a thermoset polyurethane foam having approximately spherical hollow cells that are separated or partially connected to form small, separated clusters. The binary reaction mixture does not contain trace elements other than those formed by water or the CO2-amine adduct.

[0009] 2. According to the present invention, the organic solvent-free reaction mixture for forming a chemical mechanical polishing (CMP polishing) layer described in item 1 above has a gelation time of 15 seconds to 3 minutes, or preferably 15 seconds to 2 minutes, at ambient temperature.

[0010] 3. According to another aspect of the present invention, there is provided a chemical mechanical polishing (CMP) pad for polishing a substrate selected from at least one of a magnetic substrate, an optical substrate, and a semiconductor substrate, the polishing pad comprising a polishing layer adapted for polishing the substrate, the polishing layer comprising a polyurethane reaction product of an organic solvent-free two-component reaction mixture comprising: (i) a liquid aromatic isocyanate component comprising one or more aromatic diisocyanates or a linear aromatic isocyanate-terminated urethane prepolymer, preferably a linear methylene diphenyl diisocyanate (MDI) prepolymer, having an unreacted isocyanate (NCO) concentration of 18 to 47 wt %, or preferably 18 to 34 wt %, based on the total solids weight of the aromatic isocyanate component; (ii) a liquid polyol component comprising one or more polymer polyols, such as polytetramethylene glycol (PTMEG), polypropylene glycol (PPG), a hexafunctional polyol, or a mixture thereof; and iii) one or more curing agents selected from the group of amines having formulas (I) and (II), [ka] In the formula, R 1、R2, R3, R4, and n are as defined above; the reaction mixture contains 55 to 75 wt. %, or preferably 55 to 68 wt. %, of the hard segment material, based on the total weight of the reaction mixture; the total amount of curing agents (I) and (II) is in the range of 9 to 41 wt. %, or preferably 20 to 30 wt. %, based on the total weight of the reaction mixture; the CMP polishing layer has an unfilled Shore D (2 sec) hardness of 35 to 77, preferably 55 to 77, or a filled Shore D (2 sec) hardness of 10 to 50, preferably 18 to 50, and a density of 0.43 to 0.78 g / mL, preferably greater than 0.50 to 0.78 g / mL; and the CMP polishing layer does not contain trace elements other than those formed by water or CO2-amine adducts.

[0011] 4. According to the CMP polishing pad or reaction mixture of the present invention described in any one of items 1, 2, or 3 above, the stoichiometric ratio of the sum of the total moles of amine (NH2) groups and the total moles of hydroxyl (OH) groups to the total moles of unreacted isocyanate (NCO) groups in the reaction mixture that forms the CMP polishing layer is in the range of 0.85:1.0 to 1.15:1.0, or preferably 0.9:1.0 to 1.1:1.0.

[0012] 5. According to the CMP polishing pad of the present invention described in any one of items 3 and 4 above, (i) the liquid aromatic isocyanate component is one or more diisocyanates, or an isocyanate-terminated linear urethane prepolymer compound selected from methylene diphenyl diisocyanate (MDI); toluene diisocyanate (TDI); naphthalene diisocyanate (NDI); paraphenylene diisocyanate (PPDI); or o-toluidine diisocyanate (TODI); a mixture thereof; a linear isocyanate-terminated urethane prepolymer having a hard segment material content of 84 to 100% by weight, or preferably 90 to 100% by weight, of any of MDI, TDI, NDI, PPDA, TODI, or a mixture thereof. 0% by weight 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, tripropylene glycol, and mixtures thereof, and preferably a linear isocyanate-terminated urethane prepolymer of MDI or MDI dimer extended with one or more extender compounds.

[0013] 6. According to the CMP polishing pad of the present invention described in any one of items 3, 4, or 5 above, the one or more curing agents are selected from the group of amines having formula (II) defined above, wherein n is preferably 2 or 3, and more preferably n is 2.

[0014] 7. According to the chemical mechanical polishing pad of the present invention described in any one of items 1, 2, 3, 4, 5 or 6 above, the polishing pad comprises a CMP polishing layer and further comprises a subpad or backing layer, such as a polymer-impregnated nonwoven fabric or a polymer sheet, below the polishing layer, such that the polishing layer forms the top of the polishing pad.

[0015] 8. In yet another aspect, the present invention provides a method for producing a chemical mechanical polishing (CMP) pad having a polishing layer adapted for polishing a substrate, the method comprising the steps of: preparing a two-component reaction mixture described in any one of items 1, 2, 3, 4, 5, or 6 above; mixing (i) a liquid aromatic isocyanate component and (ii) a liquid polyol component, for example, in a static mixer or an impingement mixer; and applying the reaction mixture as one component to an open mold surface, preferably having a male topography that forms a female groove pattern on the top surface of the CMP polishing pad; curing the reaction mixture at ambient temperature to 130°C to form a molded polyurethane reaction product, for example, by first curing at ambient temperature to 130°C for 1 to 30 minutes, or preferably 30 seconds to 5 minutes, removing the polyurethane reaction product from the mold, and then finally curing at a temperature of 60 to 130°C for 1 to 16 hours, or preferably 30 minutes to 6 hours.

[0016] 9. According to the method of the present invention described in item 8 above, forming the polishing pad further includes laminating a subpad layer, such as a polymer-impregnated nonwoven fabric or a porous or non-porous polymer sheet, underneath the polishing layer so that the polishing layer forms the top surface of the polishing pad.

[0017] 10. According to the method of the present invention described in either item 8 or 9 above, the method forms the surface of the CMP polishing pad directly in a mold.

[0018] 11. According to the method of the present invention described in any one of items 8, 9, or 10 above, the step of applying the reaction mixture as one component includes the steps of overspraying the mold and subsequently curing to form a polyurethane reaction product, removing the polyurethane reaction product from the mold, and then punching or cutting the periphery of the polyurethane reaction product to the desired diameter of the CMP polishing pad.

[0019] 12. In yet another aspect, the present invention provides a method for polishing a substrate, comprising: preparing a substrate selected from at least one of a magnetic substrate, an optical substrate, and a semiconductor substrate; preparing a chemical mechanical (CMP) polishing pad according to any one of items 1 to 7 above; polishing the surface of the substrate by generating dynamic contact between the polishing surface of the polishing layer of the CMP polishing pad and the substrate; and conditioning the polishing surface of the polishing pad with an abrasive conditioner.

[0020] Unless otherwise indicated, temperature and pressure conditions are ambient temperature and standard pressure. All ranges listed are inclusive and combinable.

[0021] Unless otherwise indicated, any term containing parentheses refers alternatively to the entire term and the term without them, as if the parentheses were not present, and combinations of each alternative. Thus, the term "(poly)isocyanate" refers to an isocyanate, a polyisocyanate, or a mixture thereof.

[0022] All ranges are inclusive and combinable. For example, the term "in the range of 50 to 3000 cPs, or 100 cPs or greater" would include each of 50 to 100 cPs, 50 to 3000 cPs, and 100 to 3000 cPs.

[0023] For this purpose, in the present invention, reaction mixtures are expressed in weight percent unless otherwise stated.

[0024] As used herein, the term "ASTM" refers to publications of ASTM International, West Conshohocken, PA.

[0025] As used herein, the term "average number of isocyanate groups" refers to the weighted average of the number of isocyanate groups in a mixture of aromatic isocyanate compounds. For example, a 50:50 weight percent mixture of MDI (2 NCO groups) and an isocyanurate of MDI (considered to have 3 NCO groups) has an average of 2.5 isocyanate groups.

[0026] As used herein, the term "gelation time" refers to the results obtained by mixing a given reaction mixture at approximately 65°C, for example, in a VM-2500 vortex lab mixer (StateMix Ltd., Winnipeg, Canada) set at 1000 rpm for 30 seconds, setting the timer to 0, turning the timer on, pouring the mixture into an aluminum cup, placing the cup in the hot pot of a gel timer (Gardco Hot Pot™ Gel Timer, Paul N. Gardner Company, Inc., Pompano Beach, FL) set at 65°C, stirring the reaction mixture with a wire stirrer at 20 RPM, and recording the gelation time when the wire stirrer stops moving through the sample.

[0027] As used herein, the term "hard segments" of a polyurethane reaction product or raw material from either a liquid polyol component and a liquid aromatic isocyanate component refers to the portion of the indicated reaction mixture that includes any diol, glycol, diglycol, triglycol having 6 or fewer carbon atoms, tetraglycol having 15 or fewer carbon atoms, any diamine, triamine, or polyamine, diisocyanate, triisocyanate, or reaction products thereof. Thus, "hard segments" exclude polyethers or polyglycols, such as polyethylene glycol or polypropylene glycol, or polyoxyethylenes having three or more ether groups.

[0028] As used herein, the term "trace elements other than those formed by water or CO2-amine adducts" means trace elements selected from hollow core polymeric materials such as polymer microspheres, liquid-filled hollow core polymeric materials such as fluid-filled polymeric microspheres, and fillers such as boron nitride. Pores formed in the CMP polishing layer by gas or gas-only forming blowing agents, such as CO2-amine adducts, are not considered trace elements.

[0029] As used herein, the term "polyisocyanate" means any isocyanate group-containing molecule that contains two or more isocyanate groups.

[0030] As used herein, the term "polyisocyanate prepolymer" means any isocyanate group-containing molecule that is the reaction product of an excess of a diisocyanate or polyisocyanate with an active hydrogen-containing compound that contains two or more active hydrogen groups, such as diamines, diols, triols, and polyols.

[0031] As used herein, the term "polyurethane" refers to polymerization products from di- or polyfunctional isocyanates, such as polyetherureas, polyisocyanurates, polyurethanes, polyureas, polyurethaneureas, copolymers thereof, and mixtures thereof.

[0032] As used herein, the term "curing agent" refers to low molecular weight (number average MW less than 500 g / mol) diols, diamines, and polyhydroxyl- or polyamino-functional compounds capable of terminating polyurethane prepolymers and / or forming crosslinked network structures.

[0033] As used herein, the term "reaction mixture" includes any non-reactive additives, such as trace elements, and any additives for reducing the hardness of the polyurethane reaction product in a CMP polishing pad according to ASTM D2240-15(2015).

[0034] As used herein, the term "stoichiometry" of a reaction mixture refers to the ratio of molar equivalents of (free OH groups + free NH2 groups) to free NCO groups in the reaction mixture.

[0035] As used herein, the term "SG" or "specific gravity" refers to the weight / volume ratio of a rectangle cut from a polishing pad or layer according to the present invention.

[0036] As used herein, the term "Shore D hardness" refers to the 2-second hardness of a given CMP polish, measured according to ASTM D2240-15(2015), "Standard Test Method for Rubber Property—Durometer Hardness." Hardness was measured using a Hoto Instruments P2 Auto Durometer hardness tester equipped with an Asker D Probe (Hoto Instruments, 3100 Dundee Rd, Northbrook, IL). Six samples were stacked and shuffled for each hardness measurement. Each tested pad was conditioned prior to testing by placing it at 23°C and 50% relative humidity for 5 days, using the methodology outlined in ASTM D2240-15(2015), to improve the reproducibility of the hardness test. In the present invention, the Shore D hardness of the polyurethane reaction product of the polishing layer or pad includes the Shore D hardness of that reaction product, including any additives to enhance hardness. "Filled Shore D" is obtained with a material filled with a gas, e.g., air, while "Unfilled Shore D" is obtained with a material without pores formed from a gas.

[0037] As used herein, the term "solids" refers to any materials remaining in the polyurethane reaction product of the present invention. Thus, solids include reactive, non-volatile liquids and additives that do not volatilize upon curing. Solids excludes water and volatile solvents.

[0038] As used herein, unless otherwise indicated, the term "viscosity" refers to the viscosity of a given material in neat form (100%) at a given temperature, measured using a rheometer in a 50 mm parallel plate geometry with a 100 μm gap and set to an oscillatory shear rate sweep from 0.1 to 100 rad / sec.

[0039] As used herein, unless otherwise indicated, the term "wt % NCO" refers to the amount of unreacted or free isocyanate groups in a given isocyanate or isocyanate-terminated urethane prepolymer composition.

[0040] As used herein, the term "wt.%" stands for weight percent.

[0041] In accordance with the present invention, the inventors have discovered that a CMP polishing pad having a highly porous CMP polishing layer with an unfilled Shore D (2 sec) hardness of 57-77 or a filled Shore D (2 sec) hardness of 18-50 and a density of 0.43-0.78 g / mL is a useful hard pad with attractive removal rates.

[0042] The CMP polishing pad of the present invention is formed from a two-component reaction mixture having a liquid aromatic diisocyanate component and a liquid polyol component further containing a liquid aromatic diisocyanate component. The liquid aromatic diisocyanate component includes one or more liquid aromatic diisocyanates or linear aromatic isocyanate-terminated urethane prepolymers. A suitable linear urethane prepolymer may be a methylene diphenyl isocyanate (MDI) diisocyanate prepolymer having an NCO content greater than 18% by weight. An example of such a linear aromatic isocyanate-terminated urethane prepolymer includes a prepolymer formed from MDI and (di)ethylene glycol having an NCO content of 23.0% by weight and an equivalent weight of 182 g / mol. A suitable reaction mixture further includes 5 to 30% by weight, based on the total weight of the reaction mixture, of a hydroxyl-substituted aliphatic tertiary amine as a curing agent. The amine curing agent helps to impart fast reaction times and good mechanical properties, such as high tensile strength and high tensile stress.

[0043] The hard segment of the reaction mixture ensures good mechanical properties. The hard segment may comprise 55 to 75% by weight of the reaction mixture and may include portions of both the curing agent component and the aromatic isocyanate component.

[0044] As part of the hard segment of the reaction mixture, the diisocyanate is preferably methylene diphenyl diisocyanate (MDI), which has lower toxicity compared to toluene diisocyanate (TDI). The liquid aromatic isocyanate component can include extenders or linear isocyanate-terminated urethane prepolymers formed from glycols and diglycols, or preferably short chain diols such as monoethylene glycol (MEG), dipropylene glycol (DPG), and / or tripropylene glycol (TPG).

[0045] Preferably, the liquid aromatic diisocyanate component contains only impurity levels of aliphatic isocyanates.

[0046] The soft segment of the reaction mixture can comprise a polymer polyol, such as a difunctional polyether in the (ii) polyol component. Suitable soft polyols are PTMEG and PPG. Available examples of PTMEG-containing polyols include Terathane™ 2900, 2000, 1800, 1400, 1000, 650, and 250 from Invista (Wichita, KS); Polymeg™ 2900, 2000, 1000, and 650 from Lyondell Chemicals (Limerick, PA); and PolyTHF™ 650, 1000, and 2000 from BASF Corporation (Florham Park, NJ). Available examples of PPG-containing polyols include Terathane™ 2900, 2000, 1800, 1400, 1000, 650, and 250 from Invista (Wichita, KS); Polymeg™ 2900, 2000, 1000, and 650 from Lyondell Chemicals (Limerick, PA); and PolyTHF™ 650, 1000, and 2000 from BASF Corporation (Florham Park, NJ). Arcol™ PPG-425, 725, 1000, 1025, 2000, 2025, 3025, and 4000 manufactured by Covestro (Pittsburgh, PA); Voranol™, Voralux™, and Specflex™ product lines manufactured by Dow (Midland, MI); and Multranol™, Ultracel™, Desmophen™, or Acclaim™ polyols 12200, 8200, 6300, 4200, and 2200, respectively, manufactured by Covestro (Leverkusen, DE).

[0047] The soft segment of the reaction mixture may also include one or more polyols having a polyether backbone and 5 to 7 hydroxyl groups per molecule.

[0048] Suitable polyols having a polyether backbone and 5 to 7 hydroxyl groups per molecule are available as VORANOL™ 202 polyol (Dow), which has 5 hydroxyl groups, a number average molecular weight of 590, and a hydroxyl number of 475 mg KOH / g; MULTRANOL™ 9185 polyol (Dow), which has 6 hydroxyl groups, a number average molecular weight of 3,366, and a hydroxyl number of 100 mg KOH / g; or VORANOL™ 4053 polyol (Dow), which has an average of 6.9 hydroxyl groups, a number average molecular weight of 12,420, and a hydroxyl number of 31 mg KOH / g.

[0049] The hydroxyl-substituted tertiary amine curing agent of the present invention may comprise 5 to 30 weight percent, or preferably 9 to 26.8 weight percent, based on the total solids weight of the reaction mixture.

[0050] Suitable curing agents are those selected from the group of amines having formula (I) and (II), [ka] In the formula, each R1 and R2 is independently C1-C6 alkyl, C1-C4 alkyl substituted with one or more C1-C4 alkyls or C1-C4 alkyl substituted with one or more halogens, -(CR4R5) p -S-(CR4R5) q -or -(CR4R5) p -O-(CR4R5) q-; each R3 is independently C1-C6 alkyl or C1-C4 alkyl substituted with one or more C1-C4 alkyl; each R4 and R5 is independently H or C1-C6 alkyl; each p and q is independently an integer from 1 to 5; and n is in the range of 1 to 4. However, the curing agent must be slow enough to allow mixing of the two-component reactive mixture. The curing agent, when combined with the aromatic isocyanate component and the polyol component, must cause gelation (so that the combined reactive mixture no longer flows) in at least 15 seconds, or preferably at least 20 seconds.

[0051] A catalyst may be used to enhance the reactivity of the polyol component with the diisocyanate or polyisocyanate. Suitable catalysts include any catalyst known to those skilled in the art, such as oleic acid, azelaic acid, dibutyltin dilaurate, stannous octanoate, bismuth octanoate, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), tertiary amine catalysts such as Dabco™ TMR catalyst, triethylenediamine such as DABCO™ 33LV, and mixtures thereof. Amine catalysts can accelerate the foaming reaction.

[0052] The reaction mixture of the present invention is substantially free of added organic solvents.

[0053] The specific gravity of the resulting CMP polishing pad is in the range of 0.43 to 0.78, preferably greater than 0.50 to 0.78. As the porosity increases, the bulk properties of the CMP polishing pad decrease and the removal rate (RR) increases.

[0054] The CMP polishing pad or layer of the present invention has an average pore size (X) in the range of 10 to 200 microns, or preferably 20 to 50 microns, as measured by scanning electron microscopy (SEM). 50 The stoichiometry of the reaction mixture of the present invention (NH+OH):NCO is in the range of 0.85:1.0 to 1.15:1.0.

[0055] The chemical mechanical polishing layer or pad of the present invention comprises a polishing layer that is a uniform dispersion of porous polyurethane. Uniformity is important for achieving consistent polishing pad performance. Therefore, the reaction mixture of the present invention is selected so that the resulting pad morphology is stable and easily reproducible. For example, for consistent production, it is often important to control additives such as antioxidants and impurities such as water.

[0056] According to the present invention, CMP polishing layers can be prepared by spraying a reaction mixture into an open mold and allowing it to cure. Because the two-component reaction mixture of the present invention can be sprayed or deposited as a fluid to prepare a CMP polishing layer, the reaction mixture of the present invention can react much faster than if such a layer were formed in a closed mold. The preferred gel time of the reaction mixture is 10 seconds or more at 65°C, or preferably in the range of 15 seconds to 2 minutes.

[0057] The liquid reaction mixture of the present invention can include very fast-setting compositions, where (i) the liquid aromatic isocyanate component and (ii) the liquid polyol component can gel in gel times as short as 15 seconds. The reaction must be slow enough so that the reaction mixture can be mixed in a static or impingement mixer after combining the two components. One limitation on the gel time is that the reaction mixture must react slowly enough so as not to clog the mixhead in which it is mixed and to sufficiently fill the mold when applied to the mold surface.

[0058] Preferably, the target or substrate in the method of the present invention is an open mold into which the fabricated pad will directly incorporate the groove pattern.

[0059] The CMP polishing layer of the present invention can be produced by impingement or static mixing of a reactive mixture in combination with a foaming agent, such as water or CO₂ amines (carbamates), e.g., CO₂-alkanolamine foaming agents. After impingement or static mixing, the reactive mixture is atomized through a spray nozzle toward the target with an air-induced or airless spray. In this way, a polyurethane or polyurethane-urea CMP polishing layer with a variable density ranging from 0.43 g / mL to 0.78 g / mL and with nearly spherical pores that are well-uniform throughout the pad can be obtained in a controlled process.

[0060] The rapid gel time of the reaction mixture of the present invention means that the pores formed during spraying or deposition remain in the cured CMP polishing layer. Therefore, surfactants, such as nonionic surfactants such as polyethoxylated siloxanes, are not required with the reaction mixture of the present invention to produce stable foam products.

[0061] The thermoset polyurethane foam thus formed has generally spherical hollow cells that are separate or partially interconnected to form small, discrete clusters. In one embodiment, the thermoset polyurethane has generally spherical hollow cells that are separate. In another embodiment, the thermoset polyurethane foam has generally spherical hollow cells that are partially interconnected to form small, discrete clusters. The size of the small clusters varies from 2 to 10 cells per cluster, preferably 4 to 6 cells.

[0062] Additionally, because the CMP polishing pad of the present invention is formed by spraying or foaming in the presence of a foaming agent to create bubbles, trace elements such as hollow microspheres are unnecessary and preferably absent.

[0063] Porosity is introduced into the pad or polishing layer by spraying, and the resulting pad's tensile stress is a function of both the inherent polymer tensile stress and the porosity, with increased porosity acting to decrease the specific gravity density. Thus, for a two-component spray-manufactured pad or polishing layer to provide an acceptable tensile stress, the polymer matrix tensile stress must be acceptably high, preferably greater than 100 MPa, more preferably greater than 240 MPa.

[0064] The density of the polishing layer or pad is measured according to ASTM D1622-08(2008). Density is the same as specific gravity.

[0065] For purposes of the present invention, removal rate refers to the removal rate expressed in Å / min.

[0066] The chemical mechanical polishing pad of the present invention can include a polishing layer of the polyurethane reaction product alone, or a polishing layer laminated onto a subpad or sublayer. In the case of the polishing pad of the present invention, or laminated pad, the polishing layer of the polishing pad is useful in both porous and non-porous or unfilled configurations.

[0067] Preferably, the polishing layer used in the chemical mechanical polishing pad of the present invention has an average thickness of 500 to 3750 microns (20 to 150 mils), or more preferably 750 to 3150 microns (30 to 125 mils), or even more preferably 1000 to 3000 microns (40 to 120 mils), or most preferably 1250 to 2500 microns (50 to 100 mils).

[0068] The chemical mechanical polishing pad of the present invention optionally further comprises at least one additional layer coupled to the polishing layer. Preferably, the chemical mechanical polishing pad further comprises a compressible subpad or base layer optionally attached to the polishing layer. The compressible base layer preferably improves the conformability of the polishing layer to the surface of the substrate being polished.

[0069] The polishing layer of the chemical mechanical polishing pad of the present invention has a polishing surface suitable for polishing a substrate. Preferably, the polishing surface has a macrotexture selected from at least one of perforations and grooves. The perforations can extend from the middle of the polishing surface or through the entire thickness of the polishing layer.

[0070] Preferably, the grooves are arranged in the polishing surface such that as the chemical mechanical polishing pad rotates during polishing, at least one groove sweeps over the surface of the substrate being polished.

[0071] Preferably, the polishing layer of the chemical mechanical polishing pad of the present invention has a polishing surface adapted for polishing a substrate, the polishing surface having a macrotexture formed therein, including a groove pattern selected from curved grooves, linear grooves, perforations, and combinations thereof. Preferably, the groove pattern includes a plurality of grooves. More preferably, the groove pattern is selected from groove designs such as concentric grooves (which may be circular or spiral), curved grooves, crosshatch grooves (e.g., arranged as an XY grid across the entire pad surface), other regular designs (e.g., hexagonal, triangular), tire tread patterns, irregular designs (e.g., fractal patterns), and combinations thereof. More preferably, the groove design is selected from the group consisting of random grooves, concentric grooves, spiral grooves, crosshatch grooves, XY grid grooves, hexagonal grooves, triangular grooves, fractal grooves, and combinations thereof. Most preferably, the polishing surface has a spiral groove pattern. The groove profile is preferably selected from a rectangular shape with straight sidewalls, or the groove cross section may be "V" shaped, "U" shaped, sawtooth, and combinations thereof.

[0072] According to the method of manufacturing a polishing pad according to the present invention, a chemical mechanical polishing pad can be molded with a macrotexture or groove pattern on its polishing surface to promote slurry flow and removal of polishing debris from the pad-wafer interface. Such grooves can be formed in the polishing surface of the polishing pad from the shape of a mold surface, i.e., the mold has a negative topographical version of the macrotexture.

[0073] The chemical mechanical polishing pad of the present invention can be used to polish a substrate selected from at least one of a magnetic substrate, an optical substrate, and a semiconductor substrate.

[0074] Preferably, the method for polishing a substrate of the present invention includes the steps of: providing a substrate selected from at least one of a magnetic substrate, an optical substrate, and a semiconductor substrate (preferably a semiconductor substrate such as a semiconductor wafer); providing a chemical mechanical polishing pad according to the present invention; creating dynamic contact between the polishing surface of the polishing layer and the substrate to polish the surface of the substrate; and conditioning the polishing surface with an abrasive conditioner.

[0075] Conditioning a polishing pad involves contacting a conditioning disk with the polishing surface either during intermittent breaks during polishing pauses ("ex situ") or while the CMP process is in progress ("in situ"). The conditioning disk typically has a rough conditioning surface composed of embedded diamond points that cut fine grooves into the pad surface, abrading and plowing the pad material and renewing the polishing texture. Typically, the conditioning disk rotates in a fixed position relative to the rotational axis of the polishing pad, sweeping out an annular conditioning area as the polishing pad rotates.

[0076] EXAMPLES: The invention is further described in the following non-limiting examples. Unless otherwise stated, all temperatures are at room temperature (21-23°C) and all pressures are atmospheric (approximately 760 mmHg or 101 kPa).

[0077] Notwithstanding other ingredients disclosed below, the following ingredients were used in the examples: Curing agent: N-methyldiethanolamine (MDEA) (The Dow Chemical Company, Midland, MI), and number average molecular weight, M NVoranol™ 800 (The Dow Chemical Company, Midland, MI), a tetrafunctional curing agent (OH equivalent weight 70.1) having 281 hydroxybenzoates.

[0078] MDI Prepolymer: A linear isocyanate-terminated urethane prepolymer from MDI and small molecules dipropylene glycol (DPG) and tripropylene glycol (TPG) with an NCO content of approximately 23% by weight and an equivalent weight of 182. 100% by weight of this MDI prepolymer is treated as the hard segment.

[0079] Niax™ L5345 surfactant: a nonionic organosilicon surfactant (Momentive, Columbus, OH).

[0080] Bismuth neodecanoate (BiNDE): organometallic urethane catalyst (Sigma-Aldrich, St. Louis, MO).

[0081] PTMEG####: Poly(THF) or polytetramethylene glycol is produced by the ring-opening polymerization of tetrahydrofuran (THF) and is sold as PolyTHF™ polyol (BASF, Leverkusen, DE). The number following PTMEG is the average molecular weight reported by the manufacturer. This polyol is commercially available from BASF, which sells it as PolyTHF™, and is available in three different grades with molecular weights of 650, 1000, or 2000 (PolyTHF650, PolyTHF1000, PolyTHF2000).

[0082] The characteristics of the CMP polishing pad were evaluated according to the following methods. All tensile properties were measured in accordance with ASTM D412-06a, "Standard Test Methods for Vulcanized Rubber and Thermoplastic Elastomers—Tension." Samples were cut to dog-bone C-shape dimensions. Unless otherwise indicated, five specimens were measured and the average of all specimens was reported for each analysis sample.

[0083] Hardness was measured with a Hoto Instruments P2 Auto Durometer hardness tester (Hoto Instruments, 3100 Dundee Rd, Northbrook, IL) equipped with an Asker D Probe. Pad samples were stacked and shuffled for each hardness measurement, and all samples were probed once until at least six data points were collected.

[0084] In all of the following examples, the indicated two-component reaction mixtures were mixed using impingement mixing and an air spray system with two tanks (an iso-tank and a poly-tank) and sprayed into an open mold and fed into the mixing system. The two tanks were set to given material flow rates, from which the relative amounts of each of the two components could be easily determined. The flows from the two tanks were started and stopped simultaneously.

[0085] Example 1: A two-component impingement mixing and air atomization system was used to spray the reaction mixture into an open mold. The iso-tank was charged with 100 parts MDI prepolymer, and the poly-tank was charged with 73.66 parts PolyTHF 1000, 25.34 parts Voranol™ 800, 0.99 parts Niax™ L5345 nonionic surfactant, and 0.01 parts BiNDE catalyst. The flow rates during spraying were 9.90 g / sec on the polyol side and 9.60 g / sec on the iso-side. The air injected into the nozzle was set at a nominal rate of 90 L / min. The sprayed polyurethane formulation was introduced into a mold with a grooved feature. The sprayed pad was cured in an oven set at 100°C for 10 minutes, then removed from the mold and further cured in an oven set at 100°C for 16 hours. The sprayed pad was cured in an oven at 100° C. for 10 minutes and then removed from the mold where it had been cured for 16 hours in an oven at 100° C. The resulting abrasive layer had a 62.5 wt % hard segment weight fraction at 95% stoichiometry without added water, resulting in a single-layer pad with a bulk density of 0.78 g / mL, a bulk tensile stress of 255 MPa, a tensile strength of 15.9 MPa, and a 2-second Shore D hardness of 50.

[0086] Example 2: A two-component impingement mixing and air atomization system was used to spray the reaction mixture into an open mold. The iso-tank was charged with 100 parts MDI prepolymer, and the poly-tank was charged with 74.02 parts PolyTHF 1000, 24.87 parts Voranol™ 800, 0.99 parts Niax™ L5345 nonionic surfactant, 0.01 parts BiNDE catalyst, and 0.10 parts DI water. The flow rates during spraying were 9.85 g / sec on the polyol side and 9.65 g / sec on the iso-side. The air injected into the nozzle was set at a nominal rate of 90 L / min. The sprayed polyurethane formulation was introduced into a mold with a grooved feature. The sprayed pad was cured in a 100°C oven for 10 minutes and then removed from the mold where it had been cured in the 100°C oven for 16 hours. The resulting polishing layer had a 62.5 wt. % hard segment weight fraction at 95% stoichiometry, resulting in a single-layer pad with a bulk density of 0.68 g / mL, a bulk tensile stress of 179 MPa, a tensile strength of 11.7 MPa, and a 2-second Shore D hardness of 42.

[0087] Example 3: A two-component impingement mixing and air atomization system was used to spray the reaction mixture into an open mold. The iso-tank was charged with 100 parts MDI prepolymer, and the poly-tank was charged with 74.58 parts PolyTHF 1000, 24.16 parts Voranol™ 800, 1.00 parts Niax™ L5345 nonionic surfactant, 0.01 parts BiNDE catalyst, and 0.25 parts DI water. The flow rates during spraying were 9.78 g / sec on the polyol side and 9.72 g / sec on the iso-side. The air injected into the nozzle was set at a nominal rate of 90 L / min. The sprayed polyurethane formulation was introduced into a mold with a grooved feature. The sprayed pad was cured in a 100°C oven for 10 minutes and then removed from the mold where it had been cured in the 100°C oven for 16 hours. The resulting polishing layer had a 62.5 wt. % hard segment weight fraction at 95% stoichiometry, resulting in a single-layer pad with a bulk density of 0.58 g / mL, a bulk tensile stress of 131 MPa, a tensile strength of 9.7 MPa, and a 2-second Shore D hardness of 34.

[0088] Example 4: A two-component impingement mixing and air atomization system was used to spray the reaction mixture into an open mold. The iso-tank was charged with 100 parts MDI prepolymer, and the poly-tank was charged with 74.95 parts PolyTHF1000, 23.69 parts Voranol™ 800, 1.00 parts Niax™ L5345 nonionic surfactant, 0.01 parts BiNDE catalyst, and 0.35 parts DI water. The flow rates during spraying were 9.77 g / sec on the polyol side and 9.73 g / sec on the iso-side. The air injected into the nozzle was set at a nominal rate of 90 L / min. The sprayed polyurethane formulation was introduced into a mold with a grooved feature. The sprayed pad was cured in a 100°C oven for 10 minutes and then removed from the mold where it had been cured in a 100°C oven for 16 hours. The resulting polishing layer had a 62.5 wt. % hard segment weight fraction at 95% stoichiometry, resulting in a single-layer pad with a bulk density of 0.54 g / mL, a bulk tensile stress of 124 MPa, a tensile strength of 8.2 MPa, and a 2-second Shore D hardness of 35.

[0089] Example 5: A two-component impingement mixing and air atomization system was used to spray the reaction mixture into an open mold. The iso-tank was charged with 100 parts MDI prepolymer, and the poly tank was charged with 73.33 parts PolyTHF1000, 16.23 parts Voranol™ 800, 9.19 parts MDEA, 1.00 parts Niax™ L5345 nonionic surfactant, and 0.25 parts DI water. The flow rates during spraying were 9.92 g / sec on the polyol side and 9.58 g / sec on the iso-side. The air injected into the nozzle was set at a nominal rate of 90 L / min. The sprayed polyurethane formulation was introduced into a mold with a grooved feature. The sprayed pad was cured in a 100°C oven for 10 minutes and then removed from the mold where it had been cured in a 100°C oven for 16 hours. The resulting polishing layer had a 62.5 wt % hard segment weight fraction at 105% stoichiometry, resulting in a single-layer pad with a bulk density of 0.43 g / mL, a bulk tensile stress of 20.0 MPa, a tensile strength of 4.8 MPa, and a 2-second Shore D hardness of 18.

[0090] Example 6: A two-component impingement mixing and air atomization system was used to spray the reaction mixture into an open mold. The iso-tank was charged with 100 parts MDI prepolymer, and the poly-tank was charged with 70.14 parts PolyTHF650, 18.26 parts Voranol™ 800, 10.35 parts MDEA, 1.00 parts Niax™ L5345 nonionic surfactant, and 0.25 parts DI water. The flow rates during spraying were 18.45 g / sec on the polyol side and 21.55 g / sec on the iso-side. The air injected into the nozzle was set at a nominal rate of 110 L / min. The sprayed polyurethane formulation was introduced into a mold with a grooved feature. The sprayed pad was cured in a 100°C oven for 10 minutes and then removed from the mold where it had been cured in a 100°C oven for 16 hours. The resulting polishing layer had a 67.5 wt. % hard segment weight fraction at 105% stoichiometry, resulting in a single-layer pad with a bulk density of 0.52 g / mL, a bulk tensile stress of 159 MPa, a tensile strength of 7.6 MPa, and a 2-second Shore D hardness of 40.

[0091] Example 7: A two-component impingement mixing and air atomization system was used to spray the reaction mixture into an open mold. The iso-tank was charged with 100 parts MDI prepolymer, and the poly-tank was charged with 78.04 parts PolyTHF650, 20.60 parts Voranol™ 800, 0.01 parts BiNDE catalyst, 1.00 parts Niax™ L5345 nonionic surfactant, and 0.35 parts DI water. The flow rates during spraying were 9.32 g / sec on the polyol side and 10.18 g / sec on the iso-side. The air injected into the nozzle was set at a nominal rate of 90 L / min. The sprayed polyurethane formulation was introduced into a mold with a grooved feature. The sprayed pad was cured in a 100°C oven for 10 minutes and then removed from the mold where it had been cured in the 100°C oven for 16 hours. The resulting polishing layer had a 62.5 wt. % hard segment weight fraction at 95% stoichiometry, resulting in a single-layer pad with a bulk density of 0.56 g / mL, a bulk tensile stress of 172 MPa, a tensile strength of 9.65 MPa, and a 2-second Shore D hardness of 46.

[0092] Example 8: A two-component impingement mixing and air atomization system was used to spray the reaction mixture into an open mold. The iso-tank was charged with 100 parts MDI prepolymer, and the poly-tank was charged with 71.89 parts PolyTHF650, 26.75 parts Voranol™ 800, 0.01 parts BiNDE catalyst, 1.00 parts Niax™ L5345 nonionic surfactant, and 0.35 parts DI water. The flow rates during spraying were 8.78 g / sec on the polyol side and 10.72 g / sec on the iso-side. The air injected into the nozzle was set at a nominal rate of 90 L / min. The sprayed polyurethane formulation was introduced into a mold with a grooved feature. The sprayed pad was cured in a 100°C oven for 10 minutes and then removed from the mold where it had been cured in the 100°C oven for 16 hours. The resulting polishing layer had a 67.5 wt. % hard segment weight fraction at 95% stoichiometry, resulting in a single-layer pad with a bulk density of 0.52 g / mL, a bulk tensile stress of 248 MPa, a tensile strength of 12.4 MPa, and a 2-second Shore D hardness of 45.

[0093] Example 9: A two-component impingement mixing and air atomization system was used to spray the reaction mixture into an open mold. The iso-tank was charged with 100 parts MDI prepolymer, and the poly-tank was charged with 30.31 parts PolyTHF 650, 44.10 parts Voranol™ 220-260, 24.23 parts Voranol™ 800, 0.01 parts BiNDE catalyst, 1.00 parts Niax™ L5345 nonionic surfactant, and 0.35 parts DI water. The flow rates during spraying were 17.39 g / sec on the polyol side and 22.61 g / sec on the iso-side. The air injected into the nozzle was set at a nominal rate of 110 L / min. The sprayed polyurethane formulation was introduced into a mold with a grooved feature. The sprayed pad was cured in a 100°C oven for 10 minutes and then removed from the mold where it had been cured in the 100°C oven for 16 hours. The resulting polishing layer had a 67.5 wt. % hard segment weight fraction at 95% stoichiometry, resulting in a single-layer pad with a bulk density of 0.47 g / mL, a bulk tensile stress of 248 MPa, a tensile strength of 15.9 MPa, and a 2-second Shore D hardness of 45.

[0094] Comparative Example 1: Using a two-component impingement mixing and air atomization system, the reaction mixture was sprayed into an open mold. The iso-tank was charged with 100 parts MDI prepolymer, and the poly-tank was charged with 69.83 parts PolyTHF1000, 4.07 parts Voranol™ 800, 24.85 parts Ethacure® 300, 1.00 parts Niax™ L5345 nonionic surfactant, and 0.25 parts DI water. The flow rates during spraying were 10.42 g / sec on the polyol side and 9.08 g / sec on the iso-side. The air injected into the nozzle was set at a nominal rate of 90 L / min. The sprayed polyurethane formulation was introduced into a mold with a grooved feature. The sprayed pad was cured in an oven at 100°C for 10 minutes and then removed from the mold where it had been cured in the oven at 100°C for 16 hours. The resulting polishing layer had a 62.5 wt % hard segment weight fraction at 95% stoichiometry, resulting in a single-layer pad with a bulk density of 0.53 g / mL, a bulk tensile stress of 82.7 MPa, a tensile strength of 9.4 MPa, and a 2-second Shore D hardness of 36.

[0095] Comparative Example 2: Using a two-component impingement mixing and air atomization system, the reaction mixture was sprayed into an open mold. The iso-tank was charged with 100 parts MDI prepolymer, and the poly-tank was charged with 67.7 parts PolyTHF1000, 31.3 parts Ethacure® 300, and 1.00 parts Niax™ L5345 nonionic surfactant. The flow rates during spraying were 10.74 g / sec on the polyol side and 8.76 g / sec on the iso-side. The air injected into the nozzle was set at a nominal rate of 90 L / min. The sprayed polyurethane formulation was introduced into a mold with a grooved feature. The sprayed pad was cured in an oven at 100°C for 10 minutes and then removed from the mold where it had been cured in the oven at 100°C for 16 hours. The resulting polishing layer had a 62.5 wt % hard segment weight fraction at 95% stoichiometry, resulting in a single-layer pad with a bulk density of 0.84 g / mL, a bulk tensile stress of 296 MPa, a tensile strength of 24.6 MPa, and a 2-second Shore D hardness of 57.

[0096] Polishing experiments were performed on 300 mm wafers in an Applied Reflexion polisher (Applied Materials, Santa Clara, CA) or 200 mm wafers in a Mirra polisher (Applied Materials, Santa Clara, CA) using carrier downforces of 0.0102, 0.014, 0.017, 0.021, and 0.024 MPa (1.5, 2.0, 2.5, 3.0, and / or 3.5 psi), a slurry flow rate of 300 mL / min (200 mL / min for the Mirra polisher), and CSL9044C slurry (Fujifilm), a table rotation speed of 93 rpm, and a carrier rotation speed of 87 rpm. Saesol AF38 (Saesol) conditioner was used to condition and texture the polishing pads. Each polishing pad was conditioned in the conditioner and DI water for 30 minutes using only a downforce of 31.2 N. The polishing pads were further conditioned 100% in situ during polishing at 19 sweeps / min from 51 to 373 mm (2.0 to 14.7 in) from the center of the polishing pad with a downforce of 31.2 N. Copper wafers (Novellus) were polished for each test downforce. For performance comparison, an IC1000™ and a VisionPad™ 6000 (DuPont, CMPT) were used as controls.

[0097] The removal rate was determined by measuring the film thickness before and after polishing using a KLA-Tencor RS-200 Thin Film Metrology System (KLA Tencor, Milpitas, CA) using a 65-point diameter scan. The removal rate, in Å / min, was calculated by the change in thickness at each point for a specified polishing time.

[0098] The polishing results are summarized in Tables 1-5 below.

[0099] Table 1 shows that Examples 1-4 of the present invention had comparable and superior copper removal rates compared to the commercial VisionPad™ 6000 (300 mm wafer) using 300 mm wafers in an Applied Reflexion polisher.

[0100] [Table 1]

[0101] Table 2 shows that inventive Example 5 had a superior copper removal rate compared to the commercial VisionPad™ 6000 (300 mm wafer) using a 300 mm wafer in an Applied Reflexion polisher.

[0102] [Table 2]

[0103] Table 3 shows that Examples 6-9 of the present invention had relatively superior copper removal rates compared to the commercial IC1000™ (300 mm wafer) using 300 mm wafers in an Applied Reflexion polisher.

[0104] [Table 3]

[0105] Table 4 shows that inventive Example 3 had a comparable superior copper removal rate compared to the commercial product IC1000™, while comparative Example 1 was inferior when compared to either Example 3 or IC1000™ (300 mm wafers) using 300 mm wafers in an Applied Reflexion polisher.

[0106] [Table 4]

[0107] Table 5 shows that inventive Example 1 had a comparable superior copper removal rate compared to the commercial product IC1000™, while comparative Example 2 was inferior when compared to either Example 1 or IC1000™ using 200 mm wafers in a Mirra polisher.

[0108] [Table 5]

Claims

1. 1. A chemical mechanical polishing (CMP) pad for polishing a substrate selected from at least one of a magnetic substrate, an optical substrate, and a semiconductor substrate, the pad comprising: a polishing layer adapted to polish the substrate, the polishing layer comprising a thermosetting polyurethane foam having generally spherical hollow cells that are separated or partially connected to form small, separated clusters, the thermosetting polyurethane foam being a polyurethane reaction product of a two-component reaction mixture free of organic solvents, the two-component reaction mixture comprising: (i) a liquid aromatic isocyanate component comprising one or more aromatic diisocyanates or a linear aromatic isocyanate-terminated urethane prepolymer having an unreacted isocyanate (NCO) concentration of 18 to 47 weight percent based on the total solids weight of the liquid aromatic isocyanate component; (ii) a liquid polyol component; and (iii) one or more curing agents selected from the group of amines having formulas (I) and (II): 【Chemistry 4】 In the formula, each R １ and R ２ is independent, C １ ~C ６ Alkyl, one or more C １ ~C ４ C substituted with alkyl or one or more halogens １ ~C ４ Alkyl, -(CR ５ R ６ ) ｐ -S-(CR ５ R ６ ) ｑ - or - (CR ５ R ６ ) ｐ -O-(CR ５ R ６ ) ｑ - and R ３ is C １ ~C ６ alkyl, or one or more C １ ~C ４ Alkyl-substituted C １ ~C ４ alkyl; each R ４ are independently H or -R １ -OH; each R ５ and R ６ are independently H or C １ ~C ６ each p and q is independently an integer from 1 to 5; n is in the range of 1 to 4, the two-component reaction mixture comprises 55 to 75 wt % of a hard segment material based on the total weight of the two-component reaction mixture, the total amount of the one or more curing agents is in the range of 9 to 26.8 wt % based on the total weight of the two-component reaction mixture, and the polishing layer has an unfilled Shore D (2 sec) hardness of 57 to 77 or a filled Shore D (2 sec) hardness of 18 to 50, and a density of 0.43 to 0.78 g / mL.

2. The CMP polishing pad of claim 1 , wherein the liquid aromatic isocyanate component comprises a linear aromatic isocyanate-terminated urethane prepolymer.

3. 3. The CMP polishing pad of claim 2, wherein the one or more curing agents are selected from the group of amines having the formula (II):

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