Chemical mechanical polishing pad and preparation thereof

Abstract

The present invention relates to a chemical mechanical polishing pad having a polishing layer. The polishing layer contains an extruded sheet. The extruded sheet is a photopolymerizable composition containing a block copolymer, a UV-curable acrylate, and a photoinitiator.

Description

[0001] This invention generally relates to the field of chemical mechanical polishing (CMP) for advanced semiconductor devices. More specifically, this invention relates to a CMP pad and a method for preparing the CMP pad.

[0002] In the manufacture of integrated circuits and other electronic devices, multilayers of conductive, semiconducting, and dielectric materials are deposited onto or removed from the surface of semiconductor wafers. Various deposition techniques can be used to deposit thin layers of conductive, semiconducting, and dielectric materials. Common deposition techniques in modern processing include physical vapor deposition (PVD) (also known as sputtering), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), and electrochemical plating (ECP).

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

[0004] Chemical mechanical planarization, or chemical mechanical polishing (CMP), is a common technique used to planarize substrates such as semiconductor wafers. In conventional CMP, a wafer is mounted on a carrier assembly and positioned to contact a polishing pad in the CMP apparatus. The carrier assembly applies controlled pressure to the wafer, pressing it against the polishing pad. The pad is moved relative to the wafer by an external driving force (e.g., rotation). Simultaneously, a chemical composition (“slurry”) or other polishing fluid is provided between the wafer and the polishing pad. Thus, the wafer surface is polished and planarized through the chemical and mechanical action of the pad surface and the slurry.

[0005] Various compositions and methods have been used in the preparation of polishing pads.

[0006] U.S. Patent Nos. 6,036,579 and 6,210,254 disclose polymer polishing pads having one or more photolithography-induced surface patterns. Photolithography enables the production of useful surface patterns that are not possible with conventional machining techniques, and enables the use of other pad materials that are too soft to be patterned by conventional machining techniques.

[0007] U.S. Patent No. 7,329,170 discloses a method for producing a polishing pad having a polishing layer generated by photolithography. The method includes forming a sheet molded article from a curing composition containing at least an initiator and an energy-reactive compound to be cured by energy rays; exposing the sheet molded article to energy rays to induce modification, thereby altering the solubility of the sheet molded article in a solvent; and developing the sheet molded article after irradiation with energy rays to partially remove the cured composition with a solvent, thereby forming an embossed pattern on the surface.

[0008] U.S. Patent Application Publication No. 20050107007 discloses a polishing pad comprising a nonwoven fabric as a base matrix and a non-porous photocurable resin filling the voids between the nonwoven fabric. The photocurable resin composition contains at least one member selected from the group consisting of: hydrophilic photopolymers or oligomers, and / or hydrophilic photopolymerizable monomers.

[0009] U.S. Patent Nos. 9,067,299, 10,029,405, 9,457,520, and 9,744,724 disclose methods for manufacturing polishing layers of polishing pads. These methods include the continuous deposition of multiple layers using a 3D printer, each of the multiple polishing layers being deposited by ejecting a pad material precursor from a nozzle and solidifying the pad material precursor to form a cured pad material.

[0010] U.S. Patent No. 5,965,460 discloses a polishing pad made of a polyurethane photopolymer. This polyurethane photopolymer is formed by reacting a polyurethane prepolymer with acrylates and / or methacrylates. The polyurethane prepolymer is a reaction product of a reactant selected from the group consisting of polyesters, polyethers, polybutadiene, and mixtures thereof, with a diisocyanate.

[0011] U.S. Patent No. 8,512,427 discloses a chemical mechanical polishing pad comprising an acrylate polyurethane polishing layer, wherein the polishing layer exhibits a tensile modulus of 65 to 500 MPa; an elongation at break of 50% to 250%; a storage modulus of 25 to 200 MPa; a Shore D hardness of 25 to 75; and a wet shear rate of 1 to 10 μm / min.

[0012] There is a need for improved chemical mechanical polishing (CMP) pads with superior CMP planarization performance and increased productivity. This invention addresses this need by providing a CMP pad with a polishing layer comprising an extruded sheet formed by extrusion and subsequent UV curing of a photopolymerizable composition to improve polishing performance. The photopolymerizable composition includes a block copolymer, a UV-curable acrylate, a photoinitiator, and optionally oils and / or dyes. Summary of the Invention

[0013] One embodiment provides a chemical mechanical (CMP) polishing pad suitable for polishing at least one of semiconductor substrates, optical substrates, and magnetic substrates. The polishing pad has a polishing layer and optional sub-pads. The polishing layer includes an extruded sheet comprising a photopolymerizable composition containing a block copolymer, a UV-curable acrylate, and a photoinitiator. The block copolymer is present in an amount greater than 50 wt% based on the total weight of the extruded sheet, and the extruded sheet has a Shore D hardness in the range of 40 to 70 after curing by photochemical radiation.

[0014] Another embodiment provides a photopolymerizable composition that further comprises an oil.

[0015] Another embodiment provides that the block copolymer is a triblock copolymer.

[0016] Another embodiment provides that the triblock copolymer is a styrene block copolymer or a polyurethane block copolymer.

[0017] Another embodiment provides that the styrene block copolymer is one or more members selected from the group consisting of: styrene-butadiene-styrene (SBS) block copolymer, styrene-isoprene-styrene (SIS) block copolymer, styrene-ethylene-butene-styrene (SEBS) block copolymer, styrene-ethylene-propylene-styrene (SEPS) block copolymer, and mixtures thereof.

[0018] Another embodiment provides a block copolymer present in an amount greater than 65%.

[0019] Another embodiment provides that the acrylate is one or more members selected from the group consisting of: 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, and mixtures thereof.

[0020] Another embodiment provides an extruded sheet having a Shore D hardness in the range of 45 to 65.

[0021] Another embodiment provides an extruded sheet having a Shore D hardness in the range of 45 to 55.

[0022] Another embodiment provides a photopolymerizable composition that contains no organic solvents.

[0023] Another embodiment provides a photopolymerizable composition that further comprises a plasticizer.

[0024] Another embodiment provides a method for manufacturing an extruded sheet to be used as a polishing layer in a chemical mechanical polishing pad suitable for polishing at least one of semiconductor substrates, optical substrates, and magnetic substrates, the method comprising:

[0025] (a) Blending a photopolymerizable composition comprising a block copolymer, a UV-curable acrylate and a photoinitiator in an extruder;

[0026] (b) The mixture from step (a) is extruded onto the support through a sheet die;

[0027] (c) Passing the product of step (b) through multiple calendering rolls; and

[0028] (d) Expose the product of step (c) to photochemical radiation;

[0029] The block copolymer is present in an amount greater than 50 wt% based on the total weight of the extruded sheet, and the polished layer has a Shore D hardness in the range of 40 to 70 after UV curing in step (d).

[0030] Another embodiment provides that the method further includes an embossing step between step (c) and step (d) to form a pattern on the product of step (c).

[0031] Another embodiment provides that the extruder is a twin-screw extruder.

[0032] Those skilled in the art will more readily understand these and other features and advantages of the embodiments of the present invention by reading the following detailed description. For clarity, certain features of the disclosed embodiments described above and below as individual embodiments may also be provided in combination in a single embodiment. Conversely, different features of the disclosed embodiments described in the context of a single embodiment may also be provided individually or in any sub-combination. Detailed Implementation

[0033] Unless otherwise stated or defined, all technical and scientific terms used herein have the meanings commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0034] Unless otherwise stated, all percentages, parts, ratios, etc. are by weight.

[0035] When a quantity, concentration, or other value or parameter is given as a range, a preferred range, or a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. When numerical ranges are listed herein, unless otherwise stated, the range is intended to include its endpoints, as well as all integers and fractions within that range.

[0036] Unless otherwise specified, temperature and pressure conditions are ambient temperature and standard pressure. All listed ranges are inclusive and combinable.

[0037] Unless otherwise specified, any term containing parentheses may alternatively refer to the entire term as if it did not contain parentheses, as well as terms without parentheses, and combinations of each alternative.

[0038] As used herein, the term "ASTM" refers to the publications of ASTM International, West Conshohocken, PA.

[0039] As used herein, unless otherwise specified, the terms "molecular weight" or "average molecular weight" mean the chemical weight of a given material as reported by its manufacturer. Average molecular weight refers to the molecular weight reported for a molecular distribution in a given material, such as polymer distribution.

[0040] As used herein, the term “semiconductor wafer” is intended to encompass semiconductor substrates (such as unpatterned or patterned semiconductors), semiconductor devices, various packages for different levels of interconnect (including single-chip wafers or multi-chip wafers), substrates for light-emitting diodes (LEDs), or other components requiring solder connections.

[0041] As used herein, the term "semiconductor substrate" is defined to mean any construction containing semiconductor material. Semiconductor substrates include semiconductor devices and any substrate having one or more semiconductor layers or structures that include active or operable portions of the semiconductor device.

[0042] As used in this text, the term "semiconductor device" refers to a semiconductor substrate on which at least one microelectronic device has been or is being manufactured.

[0043] As used herein, the terms “Shore D hardness” and “Shore A hardness” are the hardness values ​​of a given material measured after a given time period, as per ASTM D2240-15 (2015), “Standard Test Method for Rubber Property – Durometer Hardness.” Hardness was measured on a Rex Hybrid hardness tester (Rex Gauge Company, Inc., Buffalo Grove, IL) equipped with either D or A probes. For each hardness measurement, four samples were stacked and shuffled; and each sample was conditioned for five days at 23°C and 50% relative humidity before testing and improving the repeatability of the hardness test using the methods outlined in ASTM D2240-15 (2015).

[0044] As used herein, the terms “radiation,” “irradiation,” or “photochemical radiation” mean radiation that typically induces polymerization of monomers and / or oligomers having olefinic unsaturated double bonds (such as acrylic acid or methacrylic acid double bonds) in the presence of a photoinitiator. Photochemical radiation can include ultraviolet radiation, visible light, and e-beam radiation. Sources of photochemical radiation can be natural sunlight or artificial radiation sources. Examples of ultraviolet radiation as photochemical radiation include, but are not limited to: UV-A radiation, falling within the wavelength range of 320 nanometers (nm) to 400 nm; UV-B radiation, falling within the wavelength range of 280 nm to 320 nm; UV-C radiation, falling within the wavelength range of 100 nm to 280 nm; and UV-V radiation, falling within the wavelength range of 400 nm to 800 nm.

[0045] The term "photoinitiator" refers to a compound that promotes polymerization when exposed to radiation and breaks down into free radicals. Photoinitiators encompass one or more compounds that promote polymerization reactions individually or together.

[0046] Unless otherwise specified, the chemicals mentioned above were obtained from Aldrich, Milwaukee, WI or other similar laboratory chemical suppliers.

[0047] Furthermore, unless the context specifically indicates otherwise, references to the singular may also include the plural (e.g., "a / kind" may refer to a / kind, or a / kind or multiple / kinds).

[0048] The polishing layer in the chemical mechanical polishing pad provided by this invention comprises an extruded sheet. The extruded sheet contains a composition comprising a block copolymer, a UV-curable acrylate, and a photoinitiator. The block copolymer is present in an amount greater than 50 wt%, more preferably 60 wt%, and most preferably 65 wt% based on the total weight of the extruded sheet. After UV curing, the extruded sheet has a Shore D hardness in the range of 40 to 70, more preferably 45 to 65, and most preferably 45 to 55, as measured according to ASTM D2240.

[0049] Preferably, the block copolymer is a styrene block copolymer or a polyurethane block copolymer. More preferably, the styrene block copolymer is one or more members selected from the group consisting of styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-ethylene-butene-styrene (SEBS), styrene-ethylene-propylene-styrene (SEPS), and mixtures thereof. More preferably, the styrene block copolymer is a styrene-butadiene-styrene (SBS) block copolymer or a styrene-isoprene-styrene (SIS) block copolymer. Most preferably, the styrene block copolymer is a styrene-butadiene-styrene (SBS) block copolymer.

[0050] Preferably, the UV-curable acrylate is one or more members selected from the group consisting of: 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, and mixtures thereof. Suitable UV-curable acrylates include, but are not limited to, 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 2-phenoxyethyl acrylate, 2-phenoxyethyl methacrylate, 2-(2-ethoxyethoxy)ethyl acrylate, alkoxylated cyclohexanediol diacrylate, alkoxylated hexanediol diacrylate, alkoxylated lauryl acrylate, alkoxylated neopentyl glycol diacrylate, alkoxylated phenolic acrylate, alkoxylated tetrahydrofuran acrylate, and aromatic dimethyl acrylate. Acrylate monomers, caprolactone acrylate, cyclohexanediol diacrylate, cyclohexanediol dimethacrylate, dibutoxyethoxyethyl adipic acid, dibutoxyethoxyethyl acrylate, diethylene glycol diacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, dipentaerythritol pentaacrylate, dipropylene glycol diacrylate, ethoxylated bisphenol A diacrylate, ethoxylated bisphenol A dimethacrylate, ethoxylated hydroxyethyl methacrylate, ethoxylated nonylphenol acrylate, ethoxylated nonylphenol methacrylate, ethoxylated... Nonylphenol methacrylate, ethoxylated pentaerythritol tetraacrylate, ethoxylated trimethylolpropane triacrylate, ethylene glycol dimethacrylate, isobornyl acrylate, isobornyl methacrylate, isodecyl acrylate, isodecyl methacrylate, lauryl acrylate, lauryl methacrylate, methoxy polyethylene glycol monoacrylate, methoxy polyethylene glycol monomethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate Acrylates, polypropylene glycol monomethacrylate, propoxylated allyl methacrylate, propoxylated glycerol triacrylate, propoxylated neopentyl glycol diacrylate, propoxylated trimethylolpropane triacrylate, stearyl acrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, tetrahydrofuran acrylate, tetrahydrofuran methacrylate, tricyclodecanediethanol diacrylate, tridecyl acrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, trimethylolpropane triacrylate, and trimethylolpropane trimethacrylate.

[0051] Preferably, at least one photoinitiator is used, and it is present in an amount from about 0.1 wt% to about 15 wt% based on the total weight of the extruded sheet. One or more photoinitiators may be between any two of the following values ​​and optionally include any two of the following values: 0.1, 0.2, 0.3, 0.4, 0.5, 1, 3, 5, 7, 9, 11, 13, and 15 wt% based on the total weight of the extruded sheet. More preferably, one or more photoinitiators are present in an amount from about 1 to about 5 wt% based on the total weight of the extruded sheet. In most embodiments, the photoinitiator is sensitive to visible or ultraviolet radiation.

[0052] As is known to those skilled in the art, many photoinitiators are suitable for use in the present invention described herein. Photoinitiators include, but are not limited to: quinones; phenanthrenequinones; polynuclear quinones; benzophenones; benzoin ethers, such as benzoin methyl ether, benzoin n-butyl ether, benzoin isobutyl ether; ketones, such as aryl ketones, oxysulfonyl ketones, sulfonyl ketones, amino ketones; acetone; acetophenones, such as hydroxyalkylphenyl acetophenone, diekoxyacetophenone, and 2,2-diethoxyacetophenone; α-halogen acetophenone; 1-hydroxycyclohexylphenyl ketone; thienylmorpholino ketone; thioxanone; methyl phenylglyoxylate; ethylphenyl polyoxyethylene; acylphosphine oxides; alkoxyphenyl-substituted phosphine oxides, such as bis(2,4,6,-trimethylbenzoyl)-phenylphosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide; peroxides; diimidazoles; benzoyl oxime esters; borates; and michalcones.

[0053] Depending on the desired final properties of the extruded sheet, the photopolymerizable composition may contain other additives. Additional additives in extruded sheet compositions include photosensitizers, plasticizers, rheology modifiers, thermal polymerization inhibitors, colorants, processing aids, antioxidants, anti-ozone agents, dyes, and fillers.

[0054] Depending on the type of polishing pad desired, the thickness of the extruded sheet can vary within a wide range. Preferably, the extruded sheet has an average thickness of 20 to 150 mils; more preferably 30 to 125 mils; and most preferably 40 to 120 mils.

[0055] method

[0056] The method for preparing an extruded sheet to be used as a polishing layer in a chemical mechanical polishing pad includes the following steps:

[0057] (a) Blending a photopolymerizable composition comprising a block copolymer, a UV-curable acrylate and a photoinitiator in an extruder;

[0058] (b) The mixture from step (a) is extruded onto the support through a sheet die;

[0059] (c) Passing the product of step (b) through multiple calendering rolls; and

[0060] (d) Expose the product of step (c) to photochemical radiation;

[0061] The block copolymer is present in an amount greater than 50 wt% based on the total weight of the polished layer, and the extruded sheet has a Shore D hardness in the range of 40 to 70 after UV curing in step (d).

[0062] In step (a), the photopolymerizable composition comprising a block copolymer, a UV-curable acrylate, and a photoinitiator is compounded in an extruder. Preferably, the extruder is a twin-screw extruder, a single-screw compounder, or a planetary roll extruder. Preferably, the composition is compounded in the absence of any organic solvents.

[0063] In step (b), the mixture from step (a) is extruded through a sheet die onto a support. Typically, the support is a polymer film, such as a polyester (PET) film. More typically, the support is a thermoplastic sheet.

[0064] In step (c), the product of step (b) is passed through multiple calendering rollers to form a flat, photocurable layer on the support. Optionally, the layer is embossed to form a pattern on the surface.

[0065] Typically, thermoforming is used when patterns need to be formed on the surface of a photocurable layer. Thermoforming is a common graphic art technique used to create raised surfaces on a substrate. It is commonly used to emboss paper, foil, and plastic films. It is capable of submicron resolution and is often used to reproduce surface holograms.

[0066] Hot embossing begins with a master image that has raised patterns that match the desired pattern in the final product. This master can be flat or spherical, the latter used for high-speed roll-to-roll applications. These masters can be any object with raised surfaces. A common method for making masters involves mechanical or laser etching. These masters can also be made using photolithography, as is commonly done in holography.

[0067] In step (d), the product of step (c) is exposed to photochemical radiation to cure the photopolymerizable composition in the photocurable layer.

[0068] In some embodiments, curing is achieved by exposing the photocurable layer to photochemical radiation, which in most embodiments is ultraviolet radiation. Examples of photochemical radiation include, but are not limited to: UV-A radiation, which falls within the wavelength range of 320 nanometers (nm) to 400 nm; UV-B radiation, which has a wavelength range of 280 nm to 320 nm; UV-C radiation, which has a wavelength range of 100 nm to 280 nm; and UV-V radiation, which has a wavelength range of 400 nm to 800 nm. Other examples of radiation may include electron beams, also known as e-beams. Many artificial radiation sources emit radiation spectra containing UV radiation with wavelengths shorter than 320 nm. Photochemical radiation with wavelengths shorter than 320 nm emits high energy and can potentially damage the skin and eyes. Radiation with longer wavelengths (such as UV-A or UV-V) emits lower energy and is considered safer than radiation with shorter wavelengths (such as UV-C or UV-B). In some embodiments, the photochemical radiation is ultraviolet radiation between 300 and 400 nm. In some other embodiments, the photochemical radiation is ultraviolet radiation between 200 and 450 nm.

[0069] The exposure time to photochemical radiation can range from a few seconds to tens of minutes, depending on the intensity and spectral energy distribution of the radiation, its distance from the photocurable layer, and the nature and amount of the photocurable composition (e.g., the thickness of the layer). In one embodiment, the layer of the curable composition is exposed to photochemical radiation for from about 0.5 to about 20 minutes, and in another embodiment, for from about 0.5 to 10 minutes. The exposure temperature is preferably ambient temperature or slightly higher, i.e., from about 20°C to about 35°C. The exposure duration and energy are sufficient to allow the exposed area of ​​the layer to crosslink downwards onto the support substrate. In some embodiments, the total radiation exposure energy (sometimes referred to as flux or energy density) required to fully cure the layer is from about 1,000 to about 30,000 millijoules per square centimeter, and in other embodiments, from about 1,500 to about 20,000 millijoules per square centimeter.

[0070] Examples of suitable visible and UV light sources include carbon arcs, mercury vapor arcs, fluorescent lamps, electron flash units, electron beam units, lasers, LEDs, and photographic floodlights. In one embodiment, a suitable UV radiation source is one or more mercury vapor lamps. In some embodiments, the mercury vapor lamp may be used at a distance of about 1.5 to about 60 inches (about 3.8 to about 153 cm) from the layer of the curable composition, and in other embodiments, at a distance of about 1.5 to about 15 inches (about 3.8 to about 38.1 cm) from the layer of the curable composition.

[0071] Preferably, the polishing surface of the polishing layer is adapted to polish the substrate by imparting a macrotexture to the polishing surface. More preferably, the polishing surface is adapted to polish the substrate by imparting a macrotexture to the polishing surface, wherein the macrotexture is selected from at least one of apertures and grooves. Apertures may extend from a portion of the polishing surface or extend through the thickness of the polishing layer. Preferably, grooves are arranged on the polishing surface such that at least one groove sweeps across the surface of the substrate being polished during polishing as the chemical mechanical polishing pad rotates. Preferably, the polishing surface has a macrotexture comprising at least one groove selected from the group consisting of: curved grooves, linear grooves, and combinations thereof.

[0072] Preferably, the polished surface is adapted to polish the substrate by imparting a macrotexture to the polished surface, wherein the macrotexture includes a groove pattern formed at the polished surface in the polished layer. Preferably, the groove pattern includes a plurality of grooves. More preferably, the groove pattern is selected from groove designs. Preferably, the groove design is selected from the group consisting of: concentric grooves (which may be circular or spiral), curved grooves, mesh grooves (e.g., arranged as an XY grid on the pad surface), other regular designs (e.g., hexagonal, triangular), tire tread type 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, mesh grooves, XY grid grooves, hexagonal grooves, triangular grooves, fractal grooves, and combinations thereof. Most preferably, the polished surface has a spiral groove pattern formed therein. The groove profile is preferably selected from rectangles with straight sidewalls, or the groove cross-section may be "V", "U", serrated, and combinations thereof.

[0073] Preferably, the polishing layer of the chemical mechanical polishing pad of the present invention has an average thickness of 20 to 150 mils; more preferably 30 to 125 mils; and most preferably 40 to 120 mils.

[0074] Preferably, the polishing layer of the chemical mechanical polishing pad of the present invention can be provided in a porous and non-porous (i.e., unfilled) configuration. Preferably, the polishing layer has a strength of ≥0.6 g / cm³ as measured according to ASTM D1622. 3 The density is [not specified]. More preferably, the polished layer has a density of 0.7 to 1.2 g / cm³ as measured according to ASTM D1622. 3 (More preferably 0.8 to 1.1, most preferably 0.95 to 1.05) density.

[0075] Preferably, the polished layer has an elongation at break of 100% to 500% (more preferably 150% to 450%; most preferably 200% to 400%) as measured according to ASTM D412.

[0076] Preferably, the polished layer has a toughness of 10 to 50 MPa (more preferably 15 to 40 MPa; most preferably 20 to 30 MPa) as measured according to ASTM D1708-10.

[0077] Preferably, the polished layer has a tensile strength of 5 to 35 MPa (more preferably 7.5 to 20 MPa; most preferably 10 to 15 MPa) as measured according to ASTM D1708-10.

[0078] Preferably, the chemical mechanical polishing pad provided by the present invention is adapted to connect with the pressure plate of a polishing machine. More preferably, the chemical mechanical polishing pad provided by the present invention is adapted to be fixed to the pressure plate of a polishing machine. Most preferably, the chemical mechanical polishing pad provided by the present invention is designed to be fixed to the pressure plate using at least one of pressure-sensitive adhesive and vacuum. Preferably, the chemical mechanical polishing pad provided by the present invention further comprises a pressure plate adhesive, wherein the pressure plate adhesive is disposed on the side of the chemical mechanical polishing pad opposite to the polishing surface.

[0079] Preferably, the chemical mechanical polishing pad provided by the present invention further includes at least one additional layer connected to the polishing layer. Preferably, the chemical mechanical polishing pad provided by the present invention further includes a compressible base layer adhered to the polishing layer. The compressible base layer preferably improves the conformability of the polishing layer to the surface of the substrate being polished. Preferably, the compressible base layer is adhered to the polishing layer by a multilayer adhesive interposed between the compressible base layer and the polishing layer. Preferably, the multilayer adhesive is selected from the group consisting of pressure-sensitive adhesives, hot-melt adhesives, pressure-sensitive adhesives, and combinations thereof. More preferably, the multilayer adhesive is selected from the group consisting of pressure-sensitive adhesives and hot-melt adhesives. Most preferably, the multilayer adhesive is a reactive hot-melt adhesive.

[0080] A crucial step in substrate polishing operations is determining the process endpoint. A common in-situ method for endpoint detection involves providing a polishing pad with a window that is transparent to light of a selected wavelength. During polishing, a light beam is guided through the window to the wafer surface, where it is reflected and returns through the window to a detector (e.g., a spectrophotometer). Based on the returned signal, characteristics of the substrate surface (e.g., film thickness thereon) can be determined for endpoint detection purposes. To facilitate such light-based endpoint methods, the chemical mechanical polishing pad provided in the method of the present invention optionally further includes an endpoint detection window. Preferably, the endpoint detection window is selected from integrated windows incorporated into the polishing layer; and insertable endpoint detection window blocks incorporated into the provided chemical mechanical polishing pad.

[0081] The following examples illustrate the present invention, but the present invention is not limited thereto.

[0082] Example

[0083] Examples of the present invention were manufactured using a Werner Pfleiderer 40mm, 12-barrel twin-screw extruder. All material components were metered into the twin-screw extruder, mixed, degassed, and pumped into sheet dies, and then passed between two calender rolls, where they mated with two PET films. One of these PET films was treated with a silicone release agent so that the cover could be removed before use. The material compositions of the two examples are shown in Table 1 below.

[0084] Table 1

[0085]

[0086] Examples of block copolymers include Kraton D1162 from Kraton Corporation and Styrolux 684D from INEOS Styrolution America LLC. Hexanediol diacrylate from Sartomer is used as the UV-curable acrylate. Benzoyl dimethyl ketal (BDK) from BASF is used as the photoinitiator.

[0087] The twin-screw extruder rotates at 300 rpm. The first barrel of the twin-screw extruder is set at 50°C to avoid premature melting of the block copolymer. The other 11 barrels are set in descending order from 180°C to approximately 100°C. The sheet die is set between 130°C and 140°C, and the calender rolls are set to approximately 90°C.

[0088] After extrusion, place the sheet sample in In the 2001E exposure unit, each face was exposed to UV light for 360 seconds. The extruded sheet was 80 mils thick and cut into 35.5” × 35.5” squares for finishing to be used as the top layer of the CMP polishing pad.

[0089] As shown in Table 2 below, the UV-cured extruded sheets have a density of approximately 1.0 and a hardness of approximately 50 (Shore D measured at 2 seconds).

[0090] Table 2

[0091]

[0092] Polishing evaluation

[0093] CMP polishing pads are constructed using polishing layers of UV-cured PP-1 and PP-2 sheets for polishing tungsten films on wafer substrates. These polishing layers are machined to create a groove pattern in the polished surface, comprising multiple concentric circular grooves with dimensions of: K7 grooves 0.76 mm (30 mil) deep, 0.51 mm (20 mil) wide, and spaced 1.78 mm (70 mil), and an additional 32 radial grooves 0.76 mm (30 mil) deep and 0.76 mm (30 mil) wide.

[0094] The polishing layer was then laminated onto a SUBA IV subpad layer, available from Rohm and Haas Electronic Materials CMP Inc., using a reactive hot melt. The resulting pad was then mounted onto a polishing platen using a double-sided pressure-sensitive adhesive film. The finished pad had a diameter of 775 mm (30.5”). A VP6000, a commercial polishing pad from Rohm and Haas, was also finished with the same groove pattern and subpad construction to serve as a control pad.

[0095] Using a CMP polishing machine (from Applied Materials, Santa Clara, CA). LK polishing of 300mm tungsten wafers. Polishing conditions included a downforce of 3.1psi, a platen speed of 80rpm, a carriage speed of 81rpm, and two polishing media flow rates of 100 and 200ml / min.

[0096] Use tungsten bulk slurry (NOVAPLANE) TM 3510) Polishing evaluation was performed. The tungsten bulk slurry contains 2.0 wt% of ultra-high purity colloidal silica particles with a diameter of approximately 60 nm and 2 wt% of H2O2, with a pH of approximately 2.5.

[0097] Prior to polishing, CMP polishing pads were run-in and dressed using a dressing disc LPX-W (Saesol Diamond Ind. Co., Ltd., Gyeonggi-do, Korea). Each new pad was run-in for 30 minutes at a downforce of 9 lbf (40 N). During polishing, a 24-second off-site dressing at 7.5 lbf (33 N) was applied between wafer polishing sessions. After polishing ten dummy wafers, three wafers were polished to determine the polishing removal rate.

[0098] The removal rate (RR) was determined by measuring the film thickness before and after polishing using an ASET F5X metrology tool (KLA-Tencor, Milpitas, CA) with a 65-point spiral scan at 3 mm edge removal (for TEOS films) and an RS200 metrology tool (KLA-Tencor, Milpitas, CA) with a 65-point diameter scan at 5 mm edge removal (for W films).

[0099] The RR results for polishing W and tetraethoxysilane (TEOS) oxide at slurry flow rates of 100 ml / min and 200 ml / min are summarized in Tables 3 and 4 below. Both pads of the present invention exhibit good adjustability of W RR and selectivity of W / TEOS RR.

[0100] Table 3

[0101]

[0102] Table 4

[0103]

Claims

1. A chemical mechanical polishing pad suitable for polishing at least one of a semiconductor substrate, an optical substrate, and a magnetic substrate, the polishing pad having a polishing layer obtained by curing an extruded sheet, the extruded sheet comprising a photopolymerizable composition containing a styrene block copolymer, a UV-curable acrylate, a polybutadiene oil, and a photoinitiator, wherein the styrene block copolymer is one or more members selected from the group consisting of styrene-butadiene-styrene (SBS) block copolymer, styrene-isoprene-styrene (SIS) block copolymer, styrene-ethylene-butene-styrene (SEBS) block copolymer, styrene-ethylene-propylene-styrene (SEPS) block copolymer, and mixtures thereof, and the styrene block copolymer is present in an amount greater than 50 wt% based on the total weight of the extruded sheet, and wherein, after UV curing, the extruded sheet has a Shore D hardness in the range of 40 to 70.

2. The chemical mechanical polishing pad as described in claim 1, wherein, The styrene block copolymer is a triblock copolymer.

3. The chemical mechanical polishing pad as described in claim 1, wherein, The styrene block copolymer is present in an amount greater than 65%.

4. The chemical mechanical polishing pad as described in claim 1, wherein, The acrylate is one or more members selected from the group consisting of: 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, and mixtures thereof.

5. The chemical mechanical polishing pad as described in claim 1, wherein, The UV-cured extruded sheet has a Shore D hardness in the range of 45 to 55.

6. The chemical mechanical polishing pad as described in claim 1, wherein, The photopolymerizable composition contains no organic solvents.

7. The chemical mechanical polishing pad as described in claim 1, wherein, The photopolymerizable composition further comprises a plasticizer.

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