Polishing pad and preparation method thereof

Abstract

The embodiment relates to a polishing pad comprising a top pad layer, wherein the polishing pad has a total biomass content of 1 to 50% by weight as measured according to ASTM D 6866; therefore, it can be environmentally friendly.

Description

Polishing Pad and Method for Preparing the Same Embodiments relate to a polishing pad for use in a chemical mechanical planarization (CMP) process for semiconductor devices. Specifically, they relate to an environmentally friendly polishing pad because it contains a biomass component, and to a process for preparing it. The chemical mechanical planarization (CMP) process in a process for manufacturing semiconductors refers to the steps of fixing a semiconductor substrate such as a wafer to a turntable and bringing it into contact with the surface of a polishing pad mounted on a platform, and relatively moving the platform and the turntable to planarize irregularities on the surface of the semiconductor substrate. In this CMP process, the polishing pad must have stable physical properties because it greatly affects the surface processing quality of the semiconductor substrate. In particular, since the polishing rate of the CMP process may vary sensitively depending on the components contained in the polishing pad and its physical properties, it is necessary to optimize the components contained in the polishing pad and its physical properties. At the same time, in recent years, with the emergence of environmental issues such as climate change, there has gradually formed a public opinion that enterprises should undertake social responsibilities through ESG management of "carbon neutrality" to build a society that can develop sustainably. Accordingly, various enterprises have attempted to manufacture various products by applying derivatives from plants rather than petroleum-based raw materials. In line with this trend, there is a need to attempt to increase environmental friendliness by applying biomass raw materials to polishing pads previously manufactured using petroleum-based raw materials. In addition, even when using such biomass raw materials, it is necessary to provide a polishing pad having physical properties that can achieve the polishing rate level required in the CMP process. [Prior Art Documents] (Patent Document 1) Korean Early Publication Patent Publication No. 2018-0044771 Technical Problem Embodiments aim to provide an environmentally friendly polishing pad having physical properties capable of achieving the polishing rate required in the CMP process. In addition, embodiments aim to provide a process for preparing a polishing pad that can effectively prepare the polishing pad. Solution to the Problem According to an embodiment, to solve the above problems, there is provided a polishing pad comprising a top cushion layer prepared from a biomass-containing composition and having a total biomass content of 1 to 50 wt% measured by ASTM D 6866 standard. According to another embodiment, there is provided a process for preparing a polishing pad, which comprises preparing a bio-based urethane prepolymer from a urethane prepolymer composition comprising an isocyanate raw material and a polyol raw material comprising a bio-polyol; preparing a bio-based composition comprising the bio-based urethane prepolymer, a curing agent and a blowing agent; and curing the bio-based composition to prepare a top cushion layer, wherein the polishing pad has a total bio-content of 1 to 50% by weight as measured by ASTM D 6866 standard. Advantageous effects of the present invention The polishing pad according to an embodiment is prepared using a composition comprising a bio-based raw material, wherein the composition and content of the bio-based raw material are optimized to adjust the content of the bio-matter contained in the polishing pad to a certain range, whereby it is possible to have the physical properties (such as hardness, modulus and the like) required in the CMP process and excellent environmental friendliness. Accordingly, when a CMP process is performed using the polishing pad according to an embodiment, a semiconductor substrate (such as a wafer) with excellent surface processing quality can be provided while achieving a high polishing rate. Best mode for carrying out the present invention Hereinafter, the present invention will be described with reference to embodiments. Here, the embodiments are not limited to those disclosed below. As long as the gist of the present invention remains unchanged, the embodiments can be modified into various forms. In this specification, in the case of referring to one element being formed, connected or combined on or under another element, it means that one element is directly or indirectly formed, connected or combined on another element in all cases. In addition, it should be understood that the criteria for the terms above and below for each component may vary depending on the direction of the object being observed. In this specification, the term "comprising" is intended to specify particular features, regions, steps, procedures, elements and / or components. Unless specifically stated to the contrary, the presence or addition of any other features, regions, steps, procedures, elements and / or components is not excluded. Unless otherwise indicated, all numbers and expressions related to the amounts of components, reaction conditions and the like used herein are to be understood as being modified by the term "about". Polishing pad One embodiment provides a polishing pad, which comprises a top cushion layer, and, if necessary, further comprises an adhesive layer and a sub-cushion layer. The polishing pad according to an embodiment is prepared using a composition comprising a bio-based raw material, wherein the composition and content of the bio-based raw material are optimized to adjust the content of the bio-matter contained in the polishing pad to a certain range, which will be described in detail with reference to FIG. 1 hereinafter. Biomass is an energy source obtained from organisms. Specifically, it can refer to an energy source including biocarbon (radioactive carbon (C14)) obtained from animal and plant resources such as trees, flowers, corn, sugarcane, grass, whale oil, algae, and the like; or organic waste resources such as livestock manure, food waste, sawdust, and the like. Meanwhile, the biomass (biocarbon) content described hereinafter may refer to the value measured according to the ASTM D 6866 standard. The ASTM D 6866 standard is a standard analytical method for determining the biomass (biocarbon) content in solid samples, liquid samples, or gaseous samples using radiometric dating or accelerator mass spectrometry (AMS) methods. The radiometric dating method may include the following processes. Specifically, a pre-treated (e.g., foreign substances removed) sample (specimen) is placed in a special vacuum device and burned to produce carbon dioxide. Then, molten lithium is mixed to prepare lithium carbide, which is then cooled, and the lithium carbide is reacted with water to produce acetylene gas. Subsequently, the acetylene gas is purified and converted into benzene using a silica-alumina catalyst. Then, benzene composed of 92% carbon is mixed with a scintillation chemical material, and the radioactivity is measured with a liquid scintillation counter for about 2 days. The accelerator mass spectrometry method may include the following processes. Specifically, a pre-treated (e.g., foreign substances removed) sample (specimen) is burned to produce purified carbon dioxide, which is then reacted with hydrogen in a special glass vacuum chamber to produce graphite. Subsequently, the graphite composed of 100% carbon is placed in an accelerator mass spectrometer and the radioactivity is measured for about 30 minutes. Top cushion layer The top cushion layer (10) employed in a polishing pad (100) according to an embodiment is suitable for polishing a semiconductor substrate (e.g., a wafer) to be polished. Such a top cushion layer (10) is prepared from a biomass-containing composition (the composition for forming the top cushion layer). Specifically, the top cushion layer (10) is prepared (formed) using a composition (A) containing a biomass raw material, where the biomass raw material may be a biomass-containing urethane prepolymer (A1). The biomass-containing urethane prepolymer (A1) may be a prepolymer obtained by the reaction of a biomass-containing polyol raw material and an isocyanate raw material. Specifically, the biomass-containing urethane prepolymer (A1) can be prepared from a urethane prepolymer composition containing a polyol raw material (A11) containing a biological polyol and an isocyanate raw material (A12). The polyol raw material (A11) containing bio-polyol can be derived from biomass and contains bio-carbon, and if it is a polyol raw material containing a bio-polyol having two or more hydroxyl groups (OH), it may not be particularly limited. Specifically, the polyol raw material (A11) may contain a bio-polyol, which contains at least one selected from the group consisting of: bio-polymer polyol (A111) and bio-monomer polyol (A112). For example, the bio-polyol may be composed of the bio-polymer polyol (A111) alone or the bio-monomer polyol (A112) alone, or it may be composed of a mixture of the bio-polymer polyol (A111) and the bio-monomer polyol (A112). The bio-polymer polyol (A111) is derived from biomass and contains bio-carbon, but if it is a multi-molecular bio-polyol having two or more hydroxyl groups (OH), it may not be particularly limited. Specifically, the bio-polymer polyol (A111) may contain at least one selected from the group consisting of: bio-polyether polyol, bio-polyester polyol, bio-polycarbonate polyol, and bio-polycaprolactam polyol. When the bio-polymer polyol (A111) contains a multi-molecular bio-polyol, it is possible to reduce the viscosity of the urethane prepolymer composition to ensure processability, while providing a polishing pad (100) having excellent flexibility, elastic resilience, permanent strain, weather resistance, and hydrolysis resistance. For example, the bio-polymer polyol (A111) may be EcoTRION H2000 or EcoTRION H1000 of SK Chemical; BI-550 or B-1184 of SK Pucore; Sovermol 1102, Sovermol 1005, Sovermol 805, or Sovermol 815 of BASF; BP-04 or BP-05 of Noroo; Priplast 2033 or Priplast 1838 of Croda; Velvetol H500, Velvetol H1000, Velvetol H2000, or Velvetol H2700 of Allessa; or a combination thereof. The biopolymer polyol (A111) may have a weight average molecular weight of 400 to 3,000 g / mol, specifically, 450 to 2,700 g / mol, 500 to 2,300 g / mol, 600 to 1,800 g / mol, 700 to 1,500 g / mol, or 800 to 1,200 g / mol. In addition, the biopolymer polyol (A111) may have a hydroxyl group value (OH-value) of 35 to 250 mg KOH / g, specifically, 45 to 230 mg KOH / g, 60 to 200 mg KOH / g, 70 to 180 mg KOH / g, 80 to 150 mg KOH / g, or 90 to 130 mg KOH / g. When the weight average molecular weight and the hydroxyl group value (OH-value) of the biopolymer polyol (A111) are each within the above ranges, it is possible to provide a polishing pad (100) having excellent flexibility, elastic resilience, permanent strain, weather resistance, and hydrolysis resistance. Such a biopolymer polyol (A111) may have a biomass content (content of biocarbon contained in the biopolymer polyol (A111)) of 20 to 100% by weight, specifically, 25 to 100% by weight, 40 to 100% by weight, 50 to 100% by weight, 60 to 100% by weight, 70 to 100% by weight, or 80 to 100% by weight based on the total weight of the biopolymer polyol (A111). When the biomass content of the biopolymer polyol (A111) is within the above range, it is possible to provide a polishing pad (100) having excellent environmental friendliness and the physical properties required in the CMP process. The biobased monomer polyol (A112) is derived from biomass and contains biocarbon, but if it is a monomolecular biopolyol having two or more hydroxyl groups (OH), it may not be particularly limited. Specifically, the biobased monomer polyol (A112) may contain at least one selected from the group consisting of bioethylene glycol, bio-diethylene glycol, bio-1,2-propanediol, bio-1,3-propanediol, bio-2-methyl-1,3-propanediol, bio-1,3-butanediol, bio-1,4-butanediol, bio-2,3-butanediol, bio-n-butanol, bio-isobutanol, bio-1,5-pentanediol, bio-2-octanol, bio-1,9-nonanediol, bio-1,10-decanediol, bio-diethylene glycol, and bio-isosorbide. When the biobased monomer polyol (A112) contains a monomolecular biopolyol, it is possible to increase the crosslink density of the urethane prepolymer composition to provide a polishing pad (100) having excellent hardness and durability. The biopolymer polyol (A112) may have a weight average molecular weight of 50 to 200 g / mol, specifically, 55 to 180 g / mol, 60 to 150 g / mol, 65 to 130 g / mol, 70 to 100 g / mol, or 75 to 90 g / mol. When the weight average molecular weight of the biopolyol (A112) is within the above range, it is possible to provide a polishing pad (100) having excellent hardness and durability. Such a biopolyol (A112) may have a biomass content (content of biocarbon contained in the biopolyol (A112)) of 100% by weight based on the total weight of the biopolyol (A112). When the biomass content of the biopolyol (A112) is within the above range, it is possible to provide a polishing pad (100) having excellent environmental friendliness and the physical properties required in the CMP process. In addition to the biopolyol, the polyol raw material (A11) may further contain a petroleum-based polyol. Specifically, the polyol raw material (A11) may contain at least one selected from the group consisting of a petroleum-based polymer polyol and a petroleum-based monomer polyol. The petroleum-based polymer polyol may contain at least one selected from the group consisting of commonly known polyether polyols, polyester polyols, polycarbonate polyols, and polycaprolactam polyols. The petroleum-based monomer polyol may contain at least one selected from the group consisting of commonly known ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, n-butanol, isobutanol, 1,5-pentanediol, 1,6-hexanediol, 2-octanol, 1,9-nonanediol, 1,10-decanediol, and isosorbide. When the polyol raw material (A11) contains both the biopolyol (a) and the petroleum-based polyol (b), the mixing ratio (a:b) may be a molar ratio of 1:0.65 to 1:3, a molar ratio of 1:0.65 to 1:1.5, a molar ratio of 1:0.65 to 1:1.25, a molar ratio of 1:0.65 to 1:0.92, a molar ratio of 1:0.68 to 1:0.90, a molar ratio of 1:0.72 to 1:0.88, a molar ratio of 1:0.75 to 1:0.86, or a molar ratio of 1:0.80 to 1:0.85. When the mixing ratio is within the above range, it is possible to provide a polishing pad (100) having excellent environmental friendliness and the physical properties required in the CMP process. Meanwhile, if the isocyanate raw material (A12) contains commonly known petroleum-based isocyanates (A121), it may not be particularly limited. Specifically, the isocyanate raw material (A12) may contain at least one selected from the group consisting of: petroleum-based aromatic diisocyanates, petroleum-based aliphatic diisocyanates, and petroleum-based cycloaliphatic diisocyanates. More specifically, the isocyanate raw material (A12) may contain at least one selected from the group consisting of: petroleum-based aromatic diisocyanates and petroleum-based cycloaliphatic diisocyanates. For example, the isocyanate raw material (A12) may contain at least one selected from the group consisting of: toluene diisocyanate, naphthalene-1,5-diisocyanate, p-phenylene diisocyanate, toluidine diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, 4,4'-methylenedicyclohexyl diisocyanate, and isophorone diisocyanate. Preferably, the isocyanate raw material (A12) may contain at least one selected from the group consisting of: toluene diisocyanate (TDI) and 4,4'-methylenedicyclohexyl diisocyanate (H12MDI). When the isocyanate raw material (A12) contains toluene diisocyanate (TDI), 4,4'-methylenedicyclohexyl diisocyanate (H12MDI), or a mixture thereof, hard segments can be formed, whereby it is possible to provide a polishing pad (100) having a desired hardness level. When toluene diisocyanate (TDI) (x) and 4,4'-methylenedicyclohexyl diisocyanate (H12MDI) (y) are mixed, their mixing ratio (x:y) is not particularly limited, but specifically, it can be a weight ratio of 3:1 to 20:1, a weight ratio of 5:1 to 18:1, a weight ratio of 7:1 to 16:1, or a weight ratio of 8:1 to 13:1. Meanwhile, the isocyanate raw material (A12) may contain bio-based isocyanates (A122). Specifically, the isocyanate raw material (A12) may contain petroleum-based isocyanates (A121) and bio-based isocyanates (A122). Bio-based isocyanates (A122) are derived from biomass and contain bio-based carbon, but if they are bio-based isocyanates having two or more isocyanate groups (NCO), they may not be particularly limited. Specifically, bio-based isocyanates (A122) may contain bio-1,5-pentamethylene diisocyanate. For example, D-370N or D-376N of STABiO can be used as bio-based isocyanates (A122). The bio-based isocyanate (A122) may have an isocyanate end group content (NCO%) of 20 to 30% by weight, specifically, 21 to 28% by weight, 22 to 26% by weight, or 23 to 25% by weight. When the NCO% of the bio-based isocyanate (A122) is within the above range, it is possible to provide a polishing pad (100) having excellent hardness and durability. Such a biological isocyanate (A122) may have a biomass content (content of biological carbon contained in the biological isocyanate (A122)) of 50 to 100% by weight, specifically 55 to 95% by weight, 60 to 90% by weight, 63 to 80% by weight, or 65 to 75% by weight based on the total weight of the biological isocyanate (A122). When the biomass content of the biological isocyanate (A122) is within the above range, it is possible to provide a polishing pad (100) having excellent environmental friendliness and physical properties required in the CMP process. Meanwhile, in the reaction of the polyol raw material (A11) (z) and the isocyanate raw material (A12) (w), the reaction ratio (z:w) of the polyol raw material (A11) (z) and the isocyanate raw material (A12) (w) is not particularly limited. However, in view of the overall physical properties of the top layer (10), it can be a weight ratio of 1:2 to 1:14, a weight ratio of 1:3 to 1:12, a weight ratio of 1:4 to 1:10, or a weight ratio of 1:5 to 1:8. In addition, the ratio (M) of the number of moles of the bio-based raw material to the total number of moles of the polyol raw material (A11) and the isocyanate raw material (A12) can be 0.11 to 0.93, 0.11 to 0.90, 0.12 to 0.85, 0.12 to 0.80, 0.13 to 0.75, 0.13 to 0.70, 0.14 to 0.65, 0.14 to 0.60, 0.15 to 0.55, 0.15 to 0.50, 0.16 to 0.45, 0.16 to 0.42, or 0.17 to 0.38. Specifically, the ratio (M) can be a value calculated according to the following Equation 1. When the ratio (M) is within the above range, it is possible to provide a polishing pad (100) having excellent environmental friendliness and physical properties required in the CMP process. [Equation 1] M = (M BP1 + M BI1 ) / (M BP1 + M P2 + M BI1 + M I2 ) In Equation 1, M BP1 is the number of moles (total number of moles) of the bio-polyol contained in the urethane prepolymer composition, M P2 is the number of moles (total number of moles) of the petroleum-based polyol contained in the urethane prepolymer composition, M BI1is the number of moles (total number of moles) of the biological isocyanate contained in the urethane prepolymer composition, and M I2 is the number of moles (total number of moles) of the petroleum-based isocyanate contained in the urethane prepolymer composition. The biomass-containing urethane prepolymer (A1) obtained by the reaction of the polyol raw material (A11) and the isocyanate raw material (A12) may have a biomass (biochar) content of 4 to 80% by weight. Specifically, the biomass content of the biomass-containing urethane prepolymer (A1) may be 4 to 78% by weight, 7 to 76% by weight, 8 to 74% by weight, 9 to 72% by weight, 10 to 69% by weight, 25 to 67% by weight, or 45 to 65% by weight based on the total weight of the biomass-containing urethane prepolymer (A1). When the biomass content of the biomass-containing urethane prepolymer (A1) is within the above range, it is possible to provide a polishing pad (100) having excellent environmental friendliness and the physical properties required in the CMP process. The biomass-containing urethane prepolymer (A1) may have a weight average molecular weight of 500 to 1,500 g / mol, specifically, 600 to 1,400 g / mol, 700 to 1,300 g / mol, or 800 to 1,200 g / mol. In addition, the biomass-containing urethane prepolymer (A1) may have an isocyanate terminal group content (NCO%) of 6 to 14% by weight, specifically, 6.5 to 13% by weight, 7 to 12% by weight, 7.5 to 11% by weight, or 8 to 10% by weight. When the weight average molecular weight and NCO% of the biomass-containing urethane prepolymer (A1) are each within the above range, it is possible to provide a polishing pad (100) having an excellent polishing rate in the CMP process. Meanwhile, the composition (A) for forming the top cushion layer (10) containing the biomass-containing urethane prepolymer (A1) may further contain a curing agent (A2) and a foaming agent (A3). The curing agent (A2) may contain a compound that undergoes a curing reaction with the biomass-containing urethane prepolymer (A1). Specifically, the curing agent (A2) may contain at least one selected from the group consisting of: aromatic amines, aliphatic amines, aromatic alcohols, and aliphatic alcohols. More specifically, the curing agent (A2) may contain at least one selected from the group consisting of: 4,4'-methylenebis(2-chloroaniline), diethyltoluenediamine, diaminodiphenylmethane, dimethylthiotoluenediamine, propylene glycol bis(p-aminobenzoate), diaminodiphenyl sulfone, m-xylenediamine, isophoronediamine, ethylenediamine, diethylenetriamine, triethylenetetramine, polypropylene diamine, polypropylene triamine, and bis(4-amino-3-chlorophenyl)methane. The content of the curing agent (A2) can be 15 to 55 parts by weight, specifically 20 to 50 parts by weight, 25 to 45 parts by weight, or 30 to 40 parts by weight, relative to 100 parts by weight of the biomass-containing urethane prepolymer (A1). When the content of the curing agent (A2) is within the above range, it is more conducive to achieving a polishing pad (100) with excellent physical properties. Meanwhile, the reaction ratio (curing reaction ratio) of the biomass-containing urethane prepolymer (A1) and the curing agent (A2) is not particularly limited, but specifically, it can be an equivalent ratio of 1:0.5 to 1:1.3, an equivalent ratio of 1:0.6 to 1:1.2, an equivalent ratio of 1:0.7 to 1:1.1, or an equivalent ratio of 1:0.8 to 1:1. When the curing reaction is carried out at the above reaction ratios, the curing reaction is optimized, and it is possible to provide a polishing pad (100) with the physical properties (hardness and modulus) required in the CMP process. The blowing agent (A3) is used to form a pore structure in the top pad layer (10), and can include at least one selected from the group consisting of: solid blowing agents, liquid blowing agents, and gas-phase blowing agents (such as inert gases, such as nitrogen, argon, helium, and the like). Specifically, the blowing agent (A3) is preferably a solid blowing agent containing expandable particles. Expandable particles are particles with the property of being expandable by heat or pressure. Their size in the final top pad layer can be determined by the heat or pressure applied in the process of preparing the top pad layer (10). Specifically, the expandable particles can include heat-expanded particles, unexpanded particles, or a combination thereof. Heat-expanded particles are particles that have been pre-heated and expanded. They refer to particles whose final size is determined by the expansion due to the heat or pressure applied during the process of preparing the top pad layer (10). The expandable particles can include a resin shell; and an expansion-inducing component encapsulated inside the shell. The resin shell can include a thermoplastic resin. Specifically, the thermoplastic resin can be at least one selected from the group consisting of: vinylidene chloride-based copolymers, acrylonitrile-based copolymers, methacrylonitrile-based copolymers, and acrylic-based copolymers. The expansion-inducing component can include at least one selected from the group consisting of: hydrocarbon compounds, chlorofluorocarbons, and tetraalkylsilane compounds. Specifically, the hydrocarbon compounds can include at least one selected from the group consisting of: ethane, ethylene, propane, propylene, n-butane, isobutane, n-butene, isobutene, n-pentane, isopentane, neopentane, n-hexane, heptane, and petroleum ether. The chlorofluorocarbons can include at least one selected from the group consisting of: trichlorofluoromethane (CCl 3 F), dichlorodifluoromethane (CCl 2F 2 ) Trichlorofluoromethane (CClF 3 ), and dichlorotetrafluoroethane (C 2 Cl 2 F 4 ). The tetraalkylsilane compound may include at least one selected from the group consisting of tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane, and trimethyl-n-propylsilane. Such a solid foaming agent may have an average particle diameter of 5 to 200 µm, specifically, 10 to 100 µm, 15 to 70 µm, or 20 to 45 µm. Here, when the solid foaming agent includes thermally expanded particles as expandable particles, the average particle diameter may refer to the average particle diameter of the thermally expanded particles themselves. Here, when the solid foaming agent includes unexpanded particles as expandable particles, the average particle diameter may refer to the average particle diameter of the particles after expansion by heat or pressure. The content of the solid foaming agent may be 0.5 to 10 parts by weight, specifically, 0.7 to 8 parts by weight, 0.9 to 6 parts by weight, or 1 to 5 parts by weight, relative to 100 parts by weight of the biomass-containing urethane prepolymer (A1). When the content of the solid foaming agent is within the above range, it is more favorable to obtain a polishing pad having excellent physical properties. In addition, the composition (A) for forming the top layer (10) containing the biomass-containing urethane prepolymer (A1) may further include additives such as a surfactant and a reaction rate controller. The surfactant is not particularly limited, but it may specifically be a silicone-based surfactant. Specifically, the reaction rate controller may include at least one selected from the group consisting of triethylenediamine, dimethylethanolamine, tetramethylbutanediamine, 2-methyl-triethylenediamine, dimethylcyclohexylamine, triethylamine, triisopropanolamine, 1,4-diazabicyclo(2,2,2)octane, bis(2-methylaminoethyl)ether, trimethylaminoethylethanolamine, N,N,N,N,N''-pentamethyldiethyldimethylaminoethylamine, dimethylaminopropylamine, dimethyldimethylbenzylamine, N-ethylmorpholine, N,N-dimethylaminoethylmorpholine, N,N-dimethylcyclohexylamine, 2-methyl-2-azabicycloheptane, dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, dioctyltin diacetate, dibutyltin maleate, bis-2-ethylhexanoic acid dibutyltin, and dibutyltin dithiol. The top cushion layer (10) prepared from the composition (A) containing such a biomass-based urethane prepolymer (A1) may have a biomass (biochar) content of 2 to 70% by weight. Specifically, the biomass content of the top cushion layer (10) may be 3 to 65% by weight, 5 to 60% by weight, 6 to 58% by weight, 7 to 56% by weight, 8 to 54% by weight, 20 to 52% by weight, or 35 to 50% by weight based on the total weight of the top cushion layer (10). When the biomass content of the top cushion layer (10) is within the above range, it is possible to provide a polishing pad (100) having excellent environmental friendliness and the physical properties required in the CMP process. The thickness of the top cushion layer (10) is not particularly limited, but may specifically be 0.5 to 5 mm, 0.8 to 4 mm, 1 to 3 mm, or 1.5 to 2.5 mm. In addition, the hardness (Shore D) of the top cushion layer (10) is not particularly limited, but may specifically be 45 to 70, 50 to 68, 53 to 65, or 56 to 60. In addition, the average size of the holes formed in the top cushion layer (10) is not particularly limited, but may specifically be 10 to 40 µm, 15 to 35 µm, 18 to 30 µm, or 20 to 25 µm. When the thickness, hardness, and average hole size of the top cushion layer (10) are each within the above ranges, the CMP process can be stably performed, and the polishing pad (100) can become lighter. Adhesive layer According to one embodiment, the adhesive layer (20) further used in the polishing pad (100) is disposed between the top cushion layer (10) and the sub-cushion layer (30) and is suitable for bonding the top cushion layer (10) and the sub-cushion layer (30). Furthermore, the adhesive layer (20) is also suitable for preventing the polishing slurry supplied to the top cushion layer (10) from leaking into the sub-cushion layer (30). The adhesive layer (20) can be prepared (formed) using a hot melt adhesive composition. The hot melt adhesive composition may contain commonly known hot melt adhesives. The hot melt adhesive may contain at least one selected from the group consisting of: polyurethane resin, polyester resin, ethylene-vinyl acetate resin, polyamide resin, and polyolefin resin. The thickness of the adhesive layer (20) is not particularly limited, but it may specifically be 5 to 30 µm, 10 to 30 µm, 20 to 27 µm, or 23 to 25 µm. When the thickness of the adhesive layer (20) is within the above range, the level of the required bonding strength (adhesive strength) between the top cushion layer (10) and the sub-cushion layer (30) can be ensured. Sub-cushion layer According to one embodiment, the sub-cushion layer (30) further used in the polishing pad (100) is disposed below the top cushion layer (10) and is suitable for stably supporting the top cushion layer (10) and absorbing and / or dispersing the impact applied to the top cushion layer (10). The sub-cushion layer (30) can be prepared (formed) using non-woven fabric, suede, or a porous pad. The thickness of the sub - cushion layer (30) is not particularly limited, but may specifically be 0.5 to 4 mm, 0.6 to 3.5 mm, 0.8 to 3 mm, or 1 to 2 mm. In addition, the hardness (Asker C) of the sub - cushion layer (30) is not particularly limited, but may specifically be 55 to 90, 60 to 85, 65 to 80, or 70 to 75. When the thickness and hardness of the sub - cushion layer (30) are each within the above - mentioned ranges, it can stably support the top - cushion layer (10), and the polishing pad (100) can become lighter. The polishing pad (100) according to one embodiment can have excellent environmental friendliness because the top - cushion layer (10) is prepared from a biomass - containing composition. In addition, the composition and content of each of the polymer raw material and the isocyanate raw material in the biomass - containing composition for preparing the top - cushion layer (10) in the polishing pad (100) according to one embodiment are optimized and controlled to include a biomass content within a specific range. Therefore, it has the physical properties required in the CMP process, and the polishing rate and the cutting - pad rate can be excellent. Specifically, the polishing pad (100) according to one embodiment can have a biomass (bio - carbon) content of 1 to 50 wt% based on the total weight of the polishing pad (100). Specifically, the biomass content of the polishing pad (100) can be 2 to 50 wt%, 3 to 50 wt%, 4 to 50 wt%, 5 to 50 wt%, 6 to 50 wt%, 7 to 50 wt%, 8 to 50 wt%, 2 to 45 wt%, 3 to 42 wt%, 4 to 38 wt%, 4.5 to 36 wt%, 5 to 34 wt%, 8 to 32 wt%, 15 to 33 wt%, or 25 to 32 wt% based on the total weight of the polishing pad (100). When the biomass content of the polishing pad (100) is within the above - mentioned range, it is possible to provide a polishing pad (100) having extremely high environmental friendliness and excellent polishing rate, cutting - pad rate, and the like in the CMP process. Meanwhile, the polishing pad (100) according to one embodiment can have a compressibility (%) of 0.3 to 1.8%, 0.4 to 1.6%, 0.5 to 1.5%, 0.6 to 1.4%, or 0.8 to 1.3%. In addition, the polishing pad (100) according to one embodiment can have a polishing rate (Å / min) of 1,900 to 4,200 Å / min, 2,500 to 4,150 Å / min, 3,000 to 4,100 Å / min, 3,500 to 4,050 Å / min, or 4,000 to 4,040 Å / min in the CMP process. In addition, the polishing pad (100) according to an embodiment may have a cutting pad rate (μm / hr) of 31 to 42 µm / hr, 31.5 to 41 µm / hr, 33 to 40.5 µm / hr, 35 to 40 µm / hr, or 38 to 39.5 µm / hr. Process for preparing a polishing pad An embodiment provides a process for preparing a polishing pad that can effectively prepare the above polishing pad. Specifically, the process for preparing a polishing pad according to an embodiment includes preparing a biomass-containing urethane prepolymer from a urethane prepolymer composition containing an isocyanate raw material and a polyol raw material containing a biological polyol; preparing a biomass-containing composition containing the biomass-containing urethane prepolymer, a curing agent, and a foaming agent; and curing the biomass-containing composition to prepare a top cushion layer, wherein the polishing pad has a total biomass content of 1 to 50 wt% measured by the ASTM D 6866 standard. Specifically, the step of preparing the biomass-containing urethane prepolymer can be carried out by filling a urethane prepolymer composition containing a polyol raw material and an isocyanate raw material into a reactor and reacting the urethane prepolymer composition. The reaction conditions are not particularly limited, but the reaction temperature can be 70 to 90 °C (specifically, 75 to 85 °C), and the reaction time can be 1 to 4 hours (specifically, 2 to 3 hours). At the same time, the descriptions of each of the polyol raw material and the isocyanate raw material are the same as those of the polyol raw material (A11) and the isocyanate raw material (A12) described above and thus will be omitted. The step of preparing the biomass-containing composition can be carried out by filling the biomass-containing urethane prepolymer, the curing agent, and the foaming agent into individual injection pipelines and mixing them. The mixing can be carried out specifically at a speed of 1,000 to 10,000 rpm, 2,500 to 8,500 rpm, or 4,000 to 7,000 rpm. Here, the foaming agent can be mixed through an injection pipeline separate from the injection pipeline of the biomass-containing urethane prepolymer, or it can be pre-mixed with the biomass-containing urethane prepolymer before the biomass-containing urethane prepolymer is filled into the injection pipeline. At the same time, the descriptions of each of the biomass-containing urethane prepolymer, the curing agent, and the foaming agent are the same as those of the biomass-containing urethane prepolymer (A1), the curing agent (A2), and the foaming agent (A3) described above and thus will be omitted. The step of preparing the top cushion layer can be carried out by injecting the biomass-containing composition into a mold and subjecting it to a curing reaction. The curing reaction conditions are not particularly limited, but the curing reaction temperature can be 60 to 130 °C (specifically, 75 to 100 °C), and the mold pressure can be 50 to 260 kg / m 2(Specifically, 80 to 180 kg / m 2 ). The procedure for preparing a polishing pad according to an embodiment may further include preparing an adhesive layer and a sub-pad layer after preparing a top pad layer. In addition, steps such as cutting the surface of the top pad layer, machining grooves on the surface of the top pad layer, inspecting the polishing pad, packaging the polishing pad, or the like may be further performed. Typical methods for preparing a polishing pad may be employed in these steps. The mode of the present invention Hereinafter, embodiments of the present invention will be described in detail with reference to examples, but the scope of the embodiments of the present invention is not limited to the examples. [Example 1] Example 1-1: Preparation of a biomass-containing urethane prepolymer A four-necked flask was filled with 165 g of toluene diisocyanate (TDI) and 25 g of 4,4'-methylenedicyclohexyl diisocyanate (H12MDI) as isocyanate raw materials; and 285 g of a biopolymer polyol (ECOTRION H1000, SK Chemical (molecular weight of 1,000 g / mol, OH-value of 102.0 to 124.7 and biomass content based on the total weight of the biopolymer polyol of 100 wt%)) and 25 g of diethylene glycol as polyol raw materials, and reacted at 80 °C for 3 hours to prepare a biomass-containing urethane prepolymer with an NCO% of 9%. Example 1-2: Preparation of a top pad layer In a casting machine equipped with an injection pipeline for an inert gas, the biomass-containing urethane prepolymer prepared in Example 1-1 was filled in a prepolymer tank, and bis(4-amino-3-chlorophenyl)methane (Ishihara) was filled in a curing agent tank. Nitrogen (N 2 ) was used as the inert gas. At the same time, 1 part by weight of a solid foaming agent (AkzoNobel) and 1 part by weight of a silicone-based surfactant (Evonik) relative to 100 parts by weight of the urethane prepolymer were fed via separate pipelines to be mixed with the urethane prepolymer. These raw materials were stirred while being fed to a mixing head at a constant rate via individual injection pipelines. In such an event, the urethane prepolymer and the curing agent were fed in an equivalent ratio of 1:1, and the inert gas nitrogen (N 2) It is injected at a rate of 0.5 to 1.5 liters per minute. The mixed raw materials are injected into a mold (1,000 mm × 1,000 mm × 3 mm) preheated to 80°C at a loading rate of 10 kg per minute, and cast to obtain a molded object. Then, the top and bottom of the molded object are each ground to a thickness of 0.5 mm to obtain a top pad (top pad layer) with a thickness of 2 mm (specific gravity of 0.82 g / cc and average pore diameter of 23.6 μm). Example 1-3: Preparation of polishing pad A sub-pad (thickness of 1.1 mm) is prepared, where the polyester fiber non-woven fabric is impregnated with a polyurethane resin. Then, the top pad prepared in Example 1-2 and the sub-pad are combined using a hot melt adhesive to prepare a polishing pad (thickness of 3.32 mm) having a structure of a top pad layer, an adhesive layer, and a sub-pad layer. [Example 2] Example 2-1: Preparation of bio-based urethane prepolymer A four-necked flask is filled with 180 g of toluene diisocyanate (TDI) as an isocyanate raw material and 25 g of 4,4'-methylenedicyclohexyl diisocyanate (H12MDI); and 265 g of a biopolymer polyol (ECOTRION H1000, SK Chemical (molecular weight of 1,000 g / mol, OH-value of 102.0 to 124.7 and bio-based content based on the total weight of the biopolymer polyol is 100 wt%)) and 25 g of bio-1,3-propanediol (molecular weight of 76 g / mol and bio-based content based on the total weight of bio-1,3-propanediol is 100 wt%) as polyol raw materials, and reacted at 80°C for 3 hours to prepare a bio-based urethane prepolymer with an NCO% of 9%. Example 2-2: Preparation of top pad layer Except for using the urethane prepolymer prepared in Example 2-1 instead of the urethane prepolymer prepared in Example 1-1, a top pad (top pad layer) (specific gravity of 0.81 g / cc and average pore diameter of 23.1 µm) is prepared in the same manner as in Example 1-2. Example 2-3: Preparation of polishing pad Except for using the top pad prepared in Example 2-2 instead of the top pad prepared in Example 1-2, a polishing pad (thickness of 3.32 mm) having a structure of a top pad layer, an adhesive layer, and a sub-pad layer is prepared in the same manner as in Example 1-3. [Example 3] Example 3-1: Preparation of bio-based urethane prepolymer A four-necked flask was filled with 175 g of toluene diisocyanate (TDI) as an isocyanate raw material and 25 g of 4,4'-methylenedicyclohexyl diisocyanate (H12MDI); and 260 g of polytetramethylene ether glycol and 25 g of bio-1,3-propanediol (molecular weight of 76 g / mol and biomass content based on the total weight of bio-1,3-propanediol being 100 wt%) as polyol raw materials, and reacted at 80 °C for 3 hours to prepare a biomass-containing urethane prepolymer with an NCO% of 9%. Example 3-2: Preparation of the top cushion layer Except for using the urethane prepolymer prepared in Example 3-1 instead of the urethane prepolymer prepared in Example 1-1, the top cushion (top cushion layer) (specific gravity of 0.82 g / cc and average pore diameter of 23.4 µm) was prepared in the same manner as in Example 1-2. Example 3-3: Preparation of the polishing pad Except for using the top cushion prepared in Example 3-2 instead of the top cushion prepared in Example 1-2, a polishing pad (thickness of 3.32 mm) having a structure of a top cushion layer, an adhesive layer, and a sub-cushion layer was prepared in the same manner as in Example 1-3. [Comparative Example 1] Comparative Example 1-1: Preparation of the biomass-containing urethane prepolymer A four-necked flask was filled with 30 g of 4,4'-methylenedicyclohexyl diisocyanate (H12MDI) and 365 g of bioisocyanate (STABiO D-376N, MITSUI CHEMICALS (molecular weight of 350 g / mol and biomass content based on the total weight of bioisocyanate being 67 wt%)) as isocyanate raw materials; and 60 g of biopolymer polyol (ECOTRION H1000, SK Chemical (molecular weight of 1,000 g / mol, OH-value of 102.0 to 124.7 and biomass content based on the total weight of biopolymer polyol being 100 wt%)) and 45 g of bio-1,3-propanediol (molecular weight of 76 g / mol and biomass content based on the total weight of bio-1,3-propanediol being 100 wt%) as polyol raw materials, and reacted at 80 °C for 3 hours to prepare a biomass-containing urethane prepolymer with an NCO% of 9%. Comparative Example 1-2: Preparation of the top cushion layer Except for using the urethane prepolymer prepared in Comparative Example 1-1 instead of the urethane prepolymer prepared in Example 1-1, the top cushion (top cushion layer) (specific gravity of 0.81 g / cc and average pore diameter of 23.1 µm) was prepared in the same manner as in Example 1-2. Comparative Example 1-3: Preparation of the polishing pad A polishing pad (with a thickness of 3.32 mm) having a structure of a top pad layer, an adhesive layer, and a sub-pad layer was prepared in the same manner as in Example 1-3, except that the top pad prepared in Comparative Examples 1-2 was used instead of the top pad prepared in Examples 1-2. [Comparative Example 2] Comparative Example 2-1: Preparation of a biomass-containing urethane prepolymer A four-necked flask was filled with 140 g of toluene diisocyanate (TDI) and 20 g of 4,4'-methylenedicyclohexyl diisocyanate (H12MDI) as isocyanate raw materials; and 340 g of polytetramethylene ether glycol as a polyol raw material, and the reaction was carried out at 80 °C for 3 hours to prepare a biomass-containing urethane prepolymer with an NCO% of 9%. Comparative Example 2-2: Preparation of the top pad layer A top pad (top pad layer) (with a specific gravity of 0.81 g / cc and an average pore diameter of 22.2 µm) was prepared in the same manner as in Example 1-2, except that the urethane prepolymer prepared in Comparative Example 2-1 was used instead of the urethane prepolymer prepared in Example 1-1. Comparative Example 2-3: Preparation of the polishing pad A polishing pad (with a thickness of 3.32 mm) having a structure of a top pad layer, an adhesive layer, and a sub-pad layer was prepared in the same manner as in Example 1-3, except that the top pad prepared in Comparative Example 2-2 was used instead of the top pad prepared in Example 1-2. [Test Example 1] Analysis of biomass content The biomass (biochar) content in each of the urethane prepolymer, the top pad layer, and the polishing pad (sample size: width 5 cm and length 5 cm) was analyzed according to ASTM D 6866 standard (using radiocarbon dating). The results are shown in Table 1 below. [Table 1] Referring to Table 1 above, in the polishing pads of Examples 1 to 3 according to one embodiment, the biomass content all meets the ranges of 1 to 50% by weight based on the total weight of the polishing pad, 2 to 70% by weight based on the total weight of the top pad layer, and 4 to 80% by weight based on the total weight of the urethane prepolymer, while the biomass content in Comparative Examples 1 and 2 does not meet the above ranges. [Test Example 2] Evaluation of physical properties The top pads, sub-pads, and polishing pads prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were each evaluated for the following physical properties. The results are shown in Table 2 below. 1. Hardness The top pad (with a thickness of 2 mm, width 5 cm, and length 5 cm) and the sub-pad (with a thickness of 1.1 mm, width 5 cm, and length 5 cm) were each stored at 25 °C for 12 hours, and the Shore D hardness and Asker C hardness were measured using a hardness tester. 2. Tensile strength Use a universal testing machine (UTM) to measure the maximum strength value of each top pad (with a thickness of 2 mm, a length of 4 cm, and a width of 1 cm) just before fracture at a speed of 50 mm / min. 3. Elongation rate Use a universal testing machine (UTM) to measure the maximum deformation length of each top pad (with a thickness of 2 mm, a length of 4 cm, and a width of 1 cm) just before rapid fracture, and obtain the ratio of the maximum deformation length to the initial length in percentage (%). 4. Compressibility Place an 85 g weight on each polishing pad (with a thickness of 3.32 mm, a width of 25 mm, and a length of 25 mm) for 30 seconds, and use a dial thickness gauge (Yasuda, 129-E) device to measure the thickness (A). Place an additional 800 g weight (85 g weight and 800 g weight) on it for 3 minutes to measure the change in thickness (B). Subsequently, calculate the compressibility ((A – B) / A × 100). 5. Polishing rate Fix each polishing pad to the platform of the CMP equipment, and set the silicon wafer (diameter: 300 mm) with its silicon oxide layer facing down. Subsequently, perform the CMP process. Specifically, polish the silicon oxide layer under a polishing load of 4.0 psi, while rotating the platform at a speed of 150 rpm for 60 seconds and supplying the calcined silica slurry to the polishing pad at a rate of 250 ml / min. After polishing, separate the silicon wafer from the carrier, install it in a spin dryer, wash it with deionized water, and then dry it with nitrogen for 15 seconds. The thickness difference before and after polishing is measured using an optical interference thickness measurement device (Keyence, SI-F80R) for drying the silicon wafer, and the polishing rate is calculated according to Equation 2 below. [Equation 2] Polishing rate (Å / min) = Polished thickness (Å) of a silicon wafer (silicon oxide layer) / Polishing time (minutes) 6. Pad cutting rate Pre-condition each grinding pad with deionized water for 10 minutes, and then condition it for 1 hour while spraying deionized water to measure the change in the thickness of the polishing pad. Here, the equipment used for conditioning is CTS AP-300HM. The dressing pressure is 6 lbf, the rotational speed is 100 to 110 rpm, and the disk used for dressing is Sasol LPX-DS2. [Table 2] Referring to Table 2 above, the polishing pads of Examples 1 to 3 (where the total biomass content was adjusted to the range of the implementation aspect) had excellent overall physical properties, while the polishing pad of Comparative Example 1 (which fell outside the range of the implementation aspect) had significantly deteriorated physical properties. In addition, even though the polishing pads of Examples 1 to 3 were manufactured using bio-polyol raw materials, they still exhibited physical properties equal to or higher than those of the polishing pad of Comparative Example 2 prepared using petroleum-based polyol raw materials. Therefore, the implementation aspect can provide a polishing pad with excellent physical properties while demonstrating environmental friendliness. 10: Top cushion layer 20: Adhesive layer 30: Sub-cushion layer 100: Polishing pad Figure 1 shows a cross-sectional view of a polishing pad according to an implementation aspect. 10: Top cushion layer 20: Adhesive layer 30: Sub-cushion layer 100: Polishing pad

Claims

1. A polishing pad comprising a top layer prepared from a biomass-containing composition and having a total biomass content of 1 to 50% by weight as measured by ASTM D 6866, wherein the hardness of the top layer is in the range of 50 Shore D to 68 Shore D, wherein the composition comprises a biomass-containing urethane prepolymer, and the biomass-containing urethane prepolymer is prepared from an urethane prepolymer composition comprising an isocyanate material and a polyol material comprising a bio-polyol, wherein the isocyanate material comprises a bio-isocyanate.

2. The polishing pad of claim 1, wherein the biomass content of the top pad layer is 2 to 70% by weight based on the total weight of the top pad layer.

3. The polishing pad of claim 1, wherein the biomass content of the biomass-containing urethane prepolymer is 4 to 80% by weight based on the total weight of the biomass-containing urethane prepolymer.

4. The polishing pad of claim 1, wherein the biopolyol comprises at least one of the following groups: biopolymer polyols and biomonomer polyols.

5. The polishing pad of claim 4, wherein the biopolymer polyol comprises at least one of the following groups: bio-polyether polyol, bio-polyester polyol, bio-polycarbonate polyol, and bio-polycaprolactam polyol.

6. The polishing pad of claim 4, wherein the bio-monomer polyol comprises at least one of the following groups: bio-ethylene glycol, bio-diethylene glycol, bio-1,2-propanediol, bio-1,3-propanediol, bio-2-methyl-1,3-propanediol, bio-1,3-butanediol, bio-1,4-butanediol, bio-2,3-butanediol, bio-n-butanol, bio-isobutanol, bio-1,5-pentanediol, bio-2-octanol, bio-1,9-nonediol, bio-1,10-decanediol, bio-diethylene glycol, and bio-isosorbitol.

7. The polishing pad of claim 1, wherein the isocyanate raw material comprises at least one of the following groups: toluene diisocyanate (TDI) and 4,4'-methylene dicyclohexyl diisocyanate (H12MDI).

8. A method for preparing a polishing pad, comprising: preparing a biomass-containing urethane prepolymer from an urethane prepolymer composition comprising an isocyanate raw material and a polyol raw material comprising a bio-polyol, wherein the isocyanate raw material comprises a bio-isocyanate; preparing a biomass-containing composition comprising the biomass-containing urethane prepolymer, a curing agent, and a foaming agent; and curing the biomass-containing composition to prepare a top layer, wherein the polishing pad has a total biomass content of 1 to 50% by weight as measured by ASTM D 6866, and wherein the hardness of the top layer falls within the range of 50 Shore D to 68 Shore D.

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