Chemical mechanical planarization pad with polished layer featuring multi-fractal embedding characteristics

Abstract

A polishing pad for chemical mechanical polishing comprises a polishing layer containing a polymer matrix, which is a reaction product of an isocyanate-terminated prepolymer and a curing agent, wherein the polymer matrix has hard and soft segments, and wherein a multi-segmented polymer component formed by pre-expanded polymer microspheres is present in the polymer matrix. The polishing pad can be manufactured by: preparing a premix of isocyanate-terminated prepolymer and pre-expanded fluid-filled polymer microspheres in a stirred tank; pumping a portion of the premix from the bottom of the stirred tank through a conduit and recirculating it to the top region of the stirred tank; mixing the portion of the premix with a curing agent to form a mixture; casting the mixture into a mold; and curing the mixture in the mold.

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 a closed-cell polyurethane, which is formed by reacting a polyol with an isocyanate to form an isocyanate-terminated prepolymer, which is then mixed with a curing agent and polymer micro-components, the mixing of which leads to a reaction to form the polishing layer. See, for example, U.S. 5,578,362 and U.S. 10,391,606. Summary of the Invention

[0006] This document discloses a polishing pad for chemical mechanical polishing, comprising: a polishing layer containing a polymer matrix, said polymer matrix being a reaction product of an isocyanate-terminated prepolymer and a curing agent, wherein said polymer matrix has hard segments and soft segments, wherein a multi-lobed polymeric element formed by pre-expanded polymer microspheres is present in said polymer matrix.

[0007] This article also discloses a method for manufacturing such polishing pads containing a multi-segmented polymer component, wherein the method comprises: preparing a premix of an isocyanate-terminated prepolymer and pre-expanded fluid-filled polymer microspheres in a stirred tank; pumping a portion of the premix from the bottom of the stirred tank through a conduit and recirculating it to the top region of the stirred tank; mixing the portion of the premix with a curing agent to form a mixture; casting the mixture into a mold; and curing the mixture in the mold.

[0008] This document further discloses a method comprising providing a substrate comprising a metal, a metal oxide, or both, and polishing the substrate using a polishing pad as disclosed herein. Attached Figure Description

[0009] Figure 1 The example polished layer is shown in a scanning electron microscope (SEM) image.

[0010] Figure 2 These are scanning electron microscope (SEM) images of the polished layers for comparison.

[0011] Figure 3 The example polished layer is shown in a scanning electron microscope (SEM) image.

[0012] Figure 4 This is a diagram of an example of polymer microspheres used to form a polishing layer.

[0013] Figure 5 This is a diagram of an example of collapsed polymer microspheres in a multi-flake form.

[0014] Figure 6 yes Figure 5 The cross-section of the collapsed polymer microspheres.

[0015] Figure 7 This is a cross-section showing an example of a collapsed polymer microsphere exhibiting a curved, slit shape. Detailed Implementation

[0016] The inventors of this invention have discovered a polishing pad with excellent polishing performance. The pad comprises a polishing layer containing a polymer matrix, which is a reaction product of an isocyanate-terminated prepolymer and a curing agent. The polymer matrix has both hard and soft segments, and a multi-segmented polymer component formed from pre-expanded polymer microspheres is present within the polymer matrix. Compared to similar pads without the multi-segmented polymer component, this polishing pad exhibits improved polishing performance.

[0017] matrix polymer

[0018] The polymer matrix is ​​preferably a polyurethane matrix. For the purposes of this specification, polyurethane includes polyurethane, polyurea, and polyurethane-urea copolymers. These polyurethane polymers are formed by blending hard and soft segments. While it is possible to maintain an amorphous shape for these hard and soft segments, it is advantageous for them to be organized into hard and soft segment domains.

[0019] 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.

[0020] The prepolymer system may contain one prepolymer or a mixture of two or more prepolymers. The wt% 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—e.g., monomers, dimers, etc.

[0021] Prepolymers can be formed from polyfunctional aromatic isocyanates (e.g., aromatic polyisocyanates) and prepolymer polyols.

[0022] 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. The prepolymer polyol 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. Preferably, the prepolymer polyol is selected from the group consisting of: polytetramethylene ether glycol, polyester polyols, polypropylene ether glycol, polycaprolactone polyols, copolymers thereof, and mixtures thereof.

[0023] 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, benzylamine diisocyanate, p-phenylene diisocyanate, diphenylmethylene diisocyanate, mixtures thereof, and their isomers. Polyfunctional aromatic isocyanates may contain less than 20 wt% 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 wt% aliphatic isocyanates.

[0024] 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 wt% range based on the total weight of the prepolymer polyol: 2.0 to 30.0, or 6.0 to 10.0 wt%. 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 may have unreacted NCO in the following ranges by wt%: 4.0 to 30.0, or 6.0 to 10.0 wt%. 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 wt%. 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.

[0025] Preferably, the prepolymer reaction product has 2.0 to 30.0 wt%, 4 to 13 wt%, 5 to 11 wt%, or 6 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-80. A, 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 wt% 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 content result in a more regular polymer structure and contribute to improved polishing pad consistency. For most prepolymers, the low free isocyanate monomer content is preferably less than 0.5 wt%. Furthermore, “conventional” prepolymers, typically with higher reaction levels (i.e., more than one polyol is end-capped with diisocyanate at each end) and higher levels of free toluene diisocyanate prepolymer, should produce similar results. In addition, low molecular weight polyol additives such as diethylene glycol, butanediol, and tripropylene glycol help control the wt% of unreacted NCO in the prepolymer reaction products.

[0026] 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 10 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 Industries, Inc., and from Anderson Development Company. IE-75AP, IE80AP, IE90AP, IE98AP, IE110AP prepolymers.

[0027] The curing agent may include any multifunctional (e.g., difunctional) curing agent suitable for reacting with isocyanate-terminated prepolymers (or oligomers). For example, a multifunctional amine (e.g., diamine) curing agent may be used. Examples of polyamine curing agents include: 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); 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; 4-chloro-3,5-diaminobenzoate isobutyl ester; 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; 4,4′-methylene-bis-o-chloroaniline [MbOCA], 4,4′-methylene-bis-(3-chloro-2,6-diethylaniline) [MCDEA]; 1,2-bis(2-aminophenylthio)ethane; 4,4′-methylene-bis-aniline; methylene-bis-methylo-aminobenzoate [MBNA].

[0028] Other multifunctional curing agents such as glycols, triols, tetraols, or hydroxyl-terminated isocyanates can also be used, with or without multifunctional amine curing agents. Suitable glycol, triol, and tetraol groups include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, lower molecular weight polytetramethylene ether glycol, 1,3-bis(2-hydroxyethoxy)benzene, 1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene, 1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}benzene, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, resorcinol-di-(β-hydroxyethyl) ether, hydroquinone-di-(β-hydroxyethyl) ether, and mixtures thereof. Preferred hydroxyl-terminated isocyanates include 1,3-bis(2-hydroxyethoxy)benzene, 1,3-bis-[2-(2-hydroxyethoxy)ethoxy]benzene, 1,3-bis-{2-[2-(2-hydroxyethoxy)ethoxy]ethoxy}benzene, 1,4-butanediol, and mixtures thereof.

[0029] 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 × (moles of amine and hydroxyl groups in the curing agent blend / moles of NCO groups in the prepolymer)). Stoichiometry can be, for example, in the range of 80% to 120%, preferably 87% to 105%.

[0030] 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 or random manner to form hard segment domains.

[0031] polymer microspheres

[0032] Pre-expanded polymer microspheres are filled with a fluid. This fluid can be a liquid. It can also be a gas or a combination of gas and liquid. If the fluid contains 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 and observed with SEM, these shells have a shape that appears hemispherical. If the fluid contains 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 the polymer microspheres is gaseous at room temperature (25°C) and above, depending on the internal pressure within the polymer shell. Isopentane trapped in the 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.

[0033] The polymer shell contains the liquid; and typically, the polymer shell contains gas under pressure. The polymer shell may be chlorine-free or substantially chlorine-free. Substantially chlorine-free means that the shell contains less than 0.1, 0.05, or 0.01 wt% chlorine based on the total weight of the polymer shell. Specific examples of polymer shells include polyacrylonitrile / methacrylonitrile shells. Furthermore, these shells may incorporate inorganic particles, such as silicates, calcium-containing, or magnesium-containing particles. These particles facilitate the separation of the polymer microspheres. Before being combined with the prepolymer, the pre-expanded polymer microspheres have been expanded to a volume-average diameter range or distribution. For this purpose, the volume-average diameter can be calculated using the following formula: Where D i It is the diameter of a particle of a given size, and v iThis refers to the frequency of occurrence of particles of that size. Typical volume average diameters range from 5 to 200, 10 to 100, 15 to 50, or 17 to 45 micrometers. For example, the volume average diameter could be approximately 20 micrometers or 40 micrometers.

[0034] 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 wt% based on the 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 wt% based on the 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.

[0035] Pre-expanded polymer microspheres may contain little or no inorganic particles in or on the polymer shell.

[0036] The polished layer disclosed in this article can have a particle size distribution of less than or equal to 1, less than or equal to 0.9, less than or equal to 0.8, or less than or equal to 0.7 g / cm³. 3 Specific gravity. Specific gravity is typically at least 0.5 g / cm³. 3 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 may have both unimodal and multimodal (e.g., bimodal, trimodal, etc.) pore size distributions.

[0037] The average volumetric size of the pores in the cured polished layer can range from about 5 micrometers to about 200 micrometers, or from 10 to about 100 micrometers.

[0038] Multi-segment polymer components

[0039] The polishing pads disclosed herein comprise a polishing layer having a multi-fractal polymer component. The multi-fractal polymer component may be a residue of collapsed or partially collapsed pre-expanded polymer microspheres. As used herein, collapse means that at least a portion of the fluid originally present in the polymer microspheres has escaped or been removed. This can result in a visual change in morphology. Figure 4 An example of a substantially spherical, pre-expanded, fluid-filled polymer microsphere 41 with a shell 42 is shown. Figure 5 An example of a collapsed polymer microsphere 51 having a shell 52 with cleavage 53 is shown. Figure 6 A cross-section of a collapsed polymer microsphere 51 with a shell 52 and lobes 53 is shown. In the cross-section, it can be seen that the lobes can take the form of substantially plate-like protrusions. Plate-like refers to a structure with a relatively low thickness compared to its length and width. The plate-like structure can be substantially planar. However, Figure 7 A cross-section of a second example of a collapsed polymer microsphere 61 with a shell 62 and lobes 63 is shown, wherein the lobes are curved. The lobes may be plate-like (with low thickness relative to length and width), but in this case, the plate-like structure is curved.

[0040] Without being bound by theory, the formation of the multi-segment polymer component may originate from the use of pre-expanded polymer microspheres with a polymer shell that is substantially chlorine-free during the processing described below.

[0041] The multi-segmented polymer component is dispersed within the polymer matrix. Furthermore, pre-expanded polymer microspheres without collapse or sag can be dispersed within the polymer matrix, thereby forming pores in the porous polished layer. The pores formed by the pre-expanded polymer microspheres without collapse or sag will typically be spherical. Although occasionally they may be slightly deformed to form ellipsoidal or substantially spherical pores. Additionally, occasionally they may be somewhat irregular but do not show substantial evidence of collapse.

[0042] The presence of multi-fractal polymer components in the polymer matrix can be measured as a percentage of the total initial loading of pre-expanded polymer microspheres in the premix. Typically, most pre-expanded microspheres do not collapse to a sufficient amount to form fractals. For example, 0.1% to 20%, or 0.5% to 15%, or 1% to 10% of the pre-expanded polymer microspheres may collapse to form multi-fractal polymer components.

[0043] Multi-fractal polymer components contain three or more, or four or more, lobes. Typically, they will have fewer than 10, fewer than 7, or more than 5 lobes. Multi-fractal polymer components may include residual pore spaces. For example, at least a portion of the collapsed residue of pre-expanded polymer microspheres may contain residual irregularly shaped pore spaces. Some lobes of the multi-fractal polymer component include plate-like protrusions projecting from a central region. The plate-like protrusions do not need to be completely flat or planar. The plate-like protrusions may include two edges of the shell of the pre-expanded polymer microspheres that are in contact with each other after collapse.

[0044] When examined under a scanning electron microscope at 50x magnification, multi-fractal polymer components (e.g., the collapse residue of pre-expanded polymer microspheres) may show no evidence of pores or cracks. It is believed that, undesirably, the fluid within the pre-expanded polymer microspheres diffuses out in this condition rather than causing the shell to rupture or leak through relatively large pores within the shell.

[0045] Multi-segment polymer components (e.g., the collapse residue of pre-expanded polymer microspheres) can have a maximum size of about 20 to about 200 micrometers (e.g., from the tip of one segment to the farthest tip of another segment).

[0046] Multi-fractal polymer components can be dispersed with uncollapsed or substantially spherical polymer microspheres. For example, in a polished layer, uncollapsed or substantially spherical polymer microspheres may be partially located between the fins or plates of an interconnected multi-fractal polymer component. See, for example... Figure 1 The distance between multiple multi-segmented polymer components or between one multi-segmented polymer component and the pre-expanded polymer microsphere (which is not collapsed or remains substantially spherical) can be three times smaller than, twice smaller than, or smaller than the volume average diameter of the pre-expanded polymer microsphere. The distance between the multiple multi-segmented polymer components or between one multi-segmented polymer component and the pre-expanded polymer microsphere can be less than 400, less than 300, less than 200, less than 100, less than 60, less than 50, less than 40, or less than 30 micrometers.

[0047] Manufacturing methods, other characteristics, and applications of polishing pads

[0048] Methods for manufacturing polished layers may include preparing a premix of a prepolymer (or oligomer) and polymer microspheres (e.g., fluid-filled, pre-expanded polymer microspheres). The prepolymer (or oligomer) may be combined with the polymer microspheres in a container. The container may be equipped with a stirrer or other agitator. The container may be equipped with an outlet for removing the flow from near the bottom of the container and a pump for recirculation to return the flow to the top of the container. The premix may be heated to ensure sufficient fluidity. For example, the premix in the tank may be maintained at a temperature in the range of 40°C to 80°C, or 45°C to 70°C, or 50°C to 60°C. The premix is ​​then provided to a separating mixer to mix it with a curing agent by controlled mixing (e.g., in a pin mixer). If necessary, the curing agent may also be heated above its melting temperature before being conveyed to the mixer. The mixture of premix and curing agent is conveyed from a mixing head to a mold to manufacture individual polished layers or to manufacture polymer blocks that can be cut to form individual polished layers. After filling the mold, the assembly can be cured at an appropriate curing temperature - for example, about 100°C to 120°C.

[0049] In addition to the polishing layer, the polishing pads disclosed herein may include one or more layers of sub-pads or base pads. An adhesive layer may be used to attach the polishing layer to the sub-pad or base pad.

[0050] The polished layer can be deformed using macroscopic textures in the form of grooves, pits, and raised elements.

[0051] The polishing pads disclosed herein can be used (preferably together with a polishing slurry) to polish substrates containing metals, dielectric materials (e.g., metal oxides), or both.

[0052] Example

[0053] Fabrication and characterization of polished layers

[0054] A premix of prepolymer and pre-expanded polymer microspheres was prepared in a stirred tank with a recirculation loop that pumped the recirculation flow from the bottom of the tank to a position near the top (where it was maintained for 1 to 3 hours with recirculation and stirring). The blend was heated to 52°C to ensure sufficient flowability. The premix was degassed under vacuum and filtered in the recirculation loop. When ready to form a polished layer, the premix and curing agent were mixed by controlled mixing. The curing agent was an aromatic diamine, which was preheated above its melting temperature. When the curing agent was 4,4'-methylenebis(2-chloroaniline) (MbOCA), it could be preheated to 116°C. When the curing agent was dimethylthiotoluene diamine (DMTDA), it could be preheated to 46°C. After removing the mixing head, the mixture was dispensed into a circular mold with a diameter of 86.4 cm (34 inches) over a 3-minute period to obtain a total pour thickness of approximately 8 cm (3 inches). Before placing the mold in the curing oven, allow the dispensed mixture to gel for 15 minutes. Then, cure the mold in the curing oven using the following cycle: gradually increase the oven setpoint temperature from ambient temperature to 104°C over 30 minutes, and then maintain the oven setpoint temperature at 104°C for 15.5 hours.

[0055] The loading of polymer microspheres was controlled to achieve 0.8 g / cm³. 3 The density of the polished layer is similar to that of the polished layer portion, or 32% of the total volume of the polished layer portion. The components used for the polished layer are shown in Table 1.

[0056] Table 1

[0057]

[0058] The scanning electron micrographs of Examples 1 and 2 are shown in Figure 1 and 3 In the image, a fragmented structure representing the residue of the pre-expanded polymer microspheres collapsing or shrinking is visible. In contrast, Comparative Example 1, which used the same prepolymer and curing agent but pre-expanded polymer microspheres containing chlorine in the shell (in an amount approximately 30% by weight based on the total mass of the shell), did not show any multi-fragmented structure. See also Figure 2 Similarly, the SEM of Comparative Example 2 did not show any multi-segment structure.

[0059] Pad manufacturing and testing

[0060] The approximately 2mm thick polishing layer, manufactured as described above, is machined to provide grooves. Each polishing layer is then attached to a sub-pad using a reactive hot melt adhesive for polishing evaluation.

[0061] For the first test, the pads with polished layers from Example 1 and Comparative Example 1 were tested using a low-pH oxide slurry containing 2% colloidal silica abrasive by weight. After pad preparation, polishing was performed at a downpressure of 3.5 psi (0.024 MPa) for 80 rpm (for the platen) and 81 rpm (for the head) for 60 seconds. The slurry flow rate was 300 ml / min. Nine blank samples (dummy) and three TEOS (tetraethyl orthosilicate) derived silica monitoring wafers were tested. The results for the pads from Example 1 and Comparative Example 1 are shown in Table 2. Compared to Comparative Example 1, which had the same construction, the pads from Example 1 showed a surprisingly high rate of TEOS-derived oxide removal, as well as fewer scratches and chatter marks.

[0062] Table 2

[0063]

[0064] Note: The estimated scratches and chatter marks refer to the total number of scratches and chatter marks estimated based on the inspection of 100 randomly selected defects.

[0065] For the second test, the pads with polished layers from Example 1 and Comparative Example 1 were tested using a low-pH tungsten slurry containing 2% colloidal silica abrasive and an additional 2.5% hydrogen peroxide by weight. After pad preparation, polishing was performed at a downpressure of 4.7 psi (0.033 MPa) for 80 rpm (for the platen) and 81 rpm (for the head) for 60 seconds. The slurry flow rate was 100 ml / min. Tungsten wafers, TEOS-derived silica wafers, and silicon nitride (SiN) wafers were run to determine the removal rate for each individual wafer type. The defect rates in scratches and chatter marks were determined from the TEOS-derived oxide wafers. The results for the pads from Example 1 and Comparative Example 1 are shown in Tables 3 and 4. Compared to Comparative Example 1, which had the same construction, the pads from Example 1 showed a surprisingly high tungsten removal rate and fewer scratches and chatter marks on the TEOS-derived oxide wafers.

[0066] Table 3

[0067]

[0068] Table 4

[0069]

[0070] For the third test, the pads with polished layers from Example 2 and Comparative Example 2 were tested using a high-pH oxide slurry containing 16% colloidal silica abrasive by weight. After pad preparation, polishing was performed at a downpressure of 5 psi (0.034 MPa) with polishing times of 93 rpm (for the platen) and 87 rpm (for the head) for 60 seconds. The slurry flow rate was 250 ml / min. Nine blank samples and three TEOS-derived silica monitoring wafers were tested. The results for the pads from Example 2 and Comparative Example 2 are shown in Table 5. Compared to Comparative Example 2, which had the same construction, the pads from Example 2 showed similar TEOS-derived oxide removal rates, but with fewer scratches and chatter marks on the TEOS-derived oxide wafers.

[0071] Table 5

[0072]

[0073] This disclosure further covers the following aspects.

[0074] Aspect 1: A polishing pad for chemical mechanical polishing includes a polishing layer comprising a polymer matrix, the polymer matrix being a reaction product of an isocyanate-terminated prepolymer and a curing agent, wherein the polymer matrix has hard segments and soft segments, and wherein a multi-segmented polymer component formed from pre-expanded polymer microspheres is present in the polymer matrix.

[0075] Aspect 2: The polishing pad as described in Aspect 1, wherein the multi-segment polymer component is a collapsed residue of pre-expanded polymer microspheres, and wherein the polishing layer further comprises pores formed by a portion of the pre-expanded polymer microspheres, wherein the microspheres maintain a substantially spherical or ellipsoidal shape.

[0076] Aspect 3: The polishing pad as described in aspect 1 or 2, wherein the multi-segment polymer component comprises three or more segments.

[0077] Aspect 4: The polishing pad as described in any of the preceding aspects, wherein at least a portion of the collapsed residue of the pre-expanded polymer microspheres comprises residual irregular pore spaces.

[0078] Aspect 5: The polishing pad as described in any of the preceding aspects, wherein at least a portion of the fragments of the multi-fractal polymer component comprises plate-like protrusions extending from a central region.

[0079] Aspect 6: The polishing pad as described in any of the preceding aspects, wherein 0.1 to 20 percent of the pre-expanded polymer microspheres form the multi-segment polymer component.

[0080] Aspect 7: A polishing pad as described in any of the preceding aspects, wherein the pre-expanded polymer microspheres comprise a polymer shell, the polymer shell having a chlorine content of less than 0.1 wt% based on the total weight of the polymer shell surrounding the fluid-filled core, wherein the fluid comprises a gas.

[0081] Aspect 8: The polishing pad as described in any of the preceding aspects, wherein the collapse residue of the pre-expanded polymer microspheres, when examined under a scanning electron microscope at 50x magnification, does not include pores or cracks.

[0082] Aspect 9: The polishing pad as described in any of the preceding aspects, wherein the pre-expanded polymer microspheres have a volume average diameter of 5 to 2000, preferably 10 to 100, more preferably 15 to 50, and most preferably 17 to 45 micrometers.

[0083] Aspect 10: The polishing pad as described in any of the preceding aspects, wherein the multi-segment polymer component has a maximum size of less than 300, preferably less than 200, and more preferably less than 100 micrometers.

[0084] Aspect 11: The polishing pad as described in any of the preceding aspects, wherein the distance between the plurality of multi-segment polymer components or between the multi-segment polymer components and the pre-expanded polymer microspheres is less than 400, preferably less than 300, more preferably less than 200, even more preferably less than 100, even more preferably less than 70, even more preferably less than 50, and most preferably less than 30 micrometers.

[0085] Aspect 12: A method of manufacturing a polishing pad as described in any of the preceding aspects comprises: preparing a premix of an isocyanate-terminated prepolymer and pre-expanded fluid-filled polymer microspheres in a mixing tank; pumping a portion of the premix from the bottom of the mixing tank through a conduit and recirculating it to the top region of the mixing tank; mixing a portion of the premix with a curing agent to form a mixture; casting the mixture into a mold; and curing the mixture in the mold.

[0086] Aspect 13: The method as described in aspect 12, wherein 0.1 to 20, preferably 0.5 to 15, or more preferably 1 to 10% of the pre-expanded polymer microspheres collapse to form a multi-segmented polymer component.

[0087] Aspect 14: The method as described in Aspect 12 or 13, wherein the pre-expanded polymer microspheres comprise a polymer shell, the polymer shell having a chlorine content of less than 0.1 wt% based on the total weight of the polymer shell surrounding a fluid-filled core, wherein the fluid comprises a gas.

[0088] Aspect 15: The method of any one of Aspects 12-14, wherein the premix comprises 0.5-7, preferably 0.75-5, more preferably 1-4.5, even more preferably 1.25-4, even more preferably 1.5 to 3.5, and most preferably 1.75 to 3 wt% of pre-expanded polymer microspheres based on the total mass of the premix and the curing agent.

[0089] Aspect 16: The method of any one of Aspects 12-15, wherein the pre-expanded polymer microspheres have a volume average diameter of 10 to 100, preferably 15 to 50, or more preferably 17 to 45 micrometers.

[0090] Aspect 17: A method of polishing, comprising providing a substrate comprising a metal, a metal oxide, or both, and polishing the substrate using a polishing pad as described in aspects 1-11.

[0091] Aspect 18: The method of aspect 17 further includes providing a polishing slurry between the pad and the substrate.

[0092] 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 wt%” and “up to 10 or 5 wt%” can be combined to form ranges “1 to 10 wt%”, or “1 to 5 wt%”, or “2 to 10 wt%”, or “2 to 5 wt%”).

[0093] 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 or objective of this disclosure.

[0094] 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.

[0095] 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 polishing pad for chemical mechanical polishing, comprising: A polished layer comprising a polymer matrix, said polymer matrix being a reaction product of an isocyanate-terminated prepolymer and a curing agent, wherein said polymer matrix has hard and soft segments, and wherein a multi-segmented polymer component formed of pre-expanded polymer microspheres is present in said polymer matrix. in, The multi-segmented polymer component is the collapsed residue of pre-expanded polymer microspheres, and the polished layer further comprises pores formed by a portion of the pre-expanded polymer microspheres, wherein the microspheres maintain a substantially spherical or ellipsoidal shape. Of which, 0.1 to 20 percent of the pre-expanded polymer microspheres form the multi-segmented polymer component.

2. The polishing pad as described in claim 1, wherein, The multi-fractal polymer component comprises three or more fractals.

3. The polishing pad as described in claim 1, wherein, At least a portion of the collapsed residue of the pre-expanded polymer microspheres contains residual irregular pore spaces.

4. The polishing pad as described in claim 1, wherein, At least a portion of the fragments of the multi-fractal polymer component include plate-like protrusions extending from the central region.

5. The polishing pad as described in claim 1, wherein, The pre-expanded polymer microspheres comprise a polymer shell, the polymer shell having a chlorine content of less than 0.1 wt% based on the total weight of the polymer shell surrounding the fluid-filled core, wherein the fluid comprises a gas.

6. The polishing pad as claimed in claim 1, wherein, When examined under a scanning electron microscope at 50x magnification, the collapse residue of the pre-expanded polymer microspheres does not include pores or cracks.

7. A method of manufacturing a polishing pad as claimed in claim 1, comprising: A premix of isocyanate-terminated prepolymer and pre-expanded fluid-filled polymer microspheres was prepared in a stirred tank. A portion of the premix is ​​pumped from the bottom of the mixing tank through a conduit and recirculated to the top region of the mixing tank. A portion of the premix is ​​mixed with a curing agent to form a mixture. The mixture is poured into a mold, and The mixture is cured in the mold.

8. A polishing method comprising providing a substrate comprising a metal, a metal oxide, or both, and polishing the substrate using a polishing pad as claimed in claim 1.

Images