Polishing pad and method of manufacturing a semiconductor device using the same

Abstract

A polishing pad according to one embodiment can reduce noise and vibration within a specific frequency range. Accordingly, the polishing pad exhibits excellent sound absorption characteristics because, according to Equation 1, when measured at frequencies from 500 Hz to 4,000 Hz, the maximum sound absorption coefficient satisfies 0.1 or greater. Therefore, since the polishing pad minimizes energy loss caused by thermal or vibrational energy during the CMP polishing process, it exhibits excellent polishing rates.

Description

Technical Field

[0001] The embodiments relate to a polishing pad for use in a chemical mechanical planarization (CMP) process for one of semiconductor devices. Specifically, these embodiments relate to a polishing pad with excellent sound absorption properties, thereby minimizing energy loss caused by thermal and vibrational energy during the CMP polishing process, and to a method for preparing the polishing pad. Prior Technology

[0002] Background of the Invention A chemical mechanical planarization (CMP) process in a method for preparing a semiconductor means the following steps: fixing a semiconductor substrate (such as a wafer) to a rotating head and contacting the surface of a polishing pad mounted on a platform, and moving the platform relative to the rotating head to planarize the unevenness on the surface of the semiconductor substrate.

[0003] In this CMP process, the polishing pad needs to have stable physical properties because it significantly affects the surface finish quality of the semiconductor substrate. In particular, since the polishing rate of the CMP process can vary sensitively depending on the composition and physical properties of the polishing pad, it is necessary to optimize the composition and physical properties of the polishing pad.

[0004] Furthermore, in CMP polishing processes, polishing is performed using frictional energy. In this case, energy loss can be caused by heat or vibration generated during the process, and this energy loss can degrade performance, such as reducing the polishing rate. Previously, to reduce energy loss, methods were employed to reduce rigidity by manufacturing softer polishing pads. However, a drawback of reducing rigidity is that it may reduce flatness. Accordingly, further research has been conducted on a polishing pad and a method for preparing the polishing pad, which minimizes energy loss to improve the polishing rate without degrading the physical properties or processability of the polishing pad. [Previous Technical Documents] (Patent Document 1) Korean Early Published Patent No. 2016-0027075 Summary of the Invention

[0005] Technical issues Accordingly, the embodiments aim to provide a polishing pad with excellent polishing rate and a method for fabricating a semiconductor device using the polishing pad. Because the polishing pad has excellent sound absorption characteristics, energy loss caused by thermal and vibrational energy during the CMP polishing process can be minimized without degrading the physical properties or processability of the polishing pad. Solution to the problem

[0006] According to one embodiment, a polishing pad includes a polishing layer comprising a urethane prepolymer, a foaming agent, and a curing agent, and according to Equation 1 below, when measured at frequencies from 500 Hz to 4,000 Hz, has a maximum sound absorption coefficient of 0.1 or greater. [Equation 1] Sound absorption coefficient=(I iI r) / I i=(I a+I t) / I i

[0007] In Equation 1, when measuring the sound pressure inside the impedance tube using a cutting and polishing pad (diameter: 45 mm) according to KS F 2814-2, Ii is the intensity of the incident sound, Ir is the intensity of the reflected sound, Ia is the intensity of the absorbed sound, and It is the intensity of the transmitted sound.

[0008] A method for preparing a semiconductor device according to another embodiment includes using a polishing pad to polish the surface of a semiconductor substrate. Advantages of the present invention

[0009] A polishing pad according to one embodiment can reduce noise and vibration within a specific frequency range. Specifically, the polishing pad has excellent sound absorption characteristics because, according to Equation 1, when measured at frequencies from 500 Hz to 4,000 Hz, the maximum sound absorption coefficient satisfies 0.1 or greater. Therefore, since the polishing pad can minimize energy loss caused by thermal or vibrational energy during the CMP polishing process, it has excellent polishing rate.

[0010] More specifically, the polishing pad comprises a urethane prepolymer, a foaming agent, and a curing agent, and the type and content of the foaming agent and the curing agent can be adjusted. Therefore, the polishing pad can reduce noise and vibration within a specific frequency range to minimize energy loss caused by vibration energy; thus, it can maximize the efficiency of frictional energy to improve the polishing rate.

[0011] Furthermore, since the polishing pad according to this embodiment can improve the polishing rate by minimizing energy loss without degrading the physical properties and processability of the polishing pad, it is possible to improve CMP performance and yield when using it to manufacture semiconductor devices. Simple Explanation of the Diagram

[0012] Figure 1 shows the results of test example 1, in which the sound absorption coefficients of the polishing pads of examples 1 to 3 and comparison examples 1 and 2 were measured according to KS F 2814-2. Figure 2 schematically illustrates a method for fabricating a semiconductor device according to one embodiment. <Graphic Component Symbols> 100: Polishing pad, 200: Platform, 300: Dresser, 400: Polishing slurry, 510: Polishing head, 520: Carrier, 600: Semiconductor substrate (wafer) Implementation

[0013] Best mode for carrying out the invention The present invention will be described in detail below with reference to embodiments. The embodiments are not limited to those disclosed herein. These embodiments can be modified in various ways as long as the spirit of the invention remains unchanged.

[0014] In this specification, the terms used to refer to various components are for the purpose of distinguishing them from each other and are not intended to limit the scope of the embodiments. Furthermore, in this specification, unless the context otherwise requires, singular expressions should be construed as also encompassing the plural.

[0015] Throughout the patent specification, when referring to a component as "comprising" an element, it is important to understand that, unless otherwise specifically described, other elements may be included rather than excluded.

[0016] In this specification, when a component is described as being formed above or below another component, or connected or coupled to one another, it covers situations where these components are formed, connected, or coupled directly or indirectly through another component. Furthermore, it should be understood that the standard for the terms "above" and "below" for each component may vary depending on the orientation in which the object is viewed.

[0017] Unless otherwise stated, all numerical ranges of the physical properties, dimensions and similar components used herein should be understood to be modified by the term "approximately".

[0018] In limiting the numerical range of the size, physical properties and similar properties of the components described in this specification, when numerical ranges using only upper limits and numerical ranges using only lower limits are exemplified separately, it should be understood that numerical ranges combining these upper and lower limits are also covered within the exemplary scope of this invention. Polishing pad

[0019] According to one embodiment, a polishing pad includes a polishing layer comprising a urethane prepolymer, a foaming agent, and a curing agent, and according to Equation 1 below, when measured at frequencies from 500 Hz to 4,000 Hz, has a maximum sound absorption coefficient of 0.1 or greater. [Equation 1] Sound absorption coefficient=(I iI r) / I i=(I a+I t) / I i

[0020] In Equation 1, when measuring the sound pressure inside the impedance tube using a cutting and polishing pad (diameter: 45 mm) according to KS F 2814-2, Ii is the intensity of the incident sound, Ir is the intensity of the reflected sound, Ia is the intensity of the absorbed sound, and It is the intensity of the transmitted sound.

[0021] According to one embodiment of the present invention, based on Equation 1 above, when measured at frequencies from 500 Hz to 4,000 Hz, the maximum sound absorption coefficient of the polishing pad is 0.1 or greater.

[0022] Specifically, according to KS F 2814-2, a polishing pad is cut, the sample is placed inside an impedance tube, and a plane wave sound source is generated inside the tube to measure the sound pressure. In this case, the operating frequency range is 500 Hz to 4,000 Hz. The measured sound pressure is used to calculate the sound absorption coefficient according to Equation 1 above.

[0023] For example, according to KS F 2814-2, when measured at frequencies of 500 Hz to 4,000 Hz, 750 Hz to 3,500 Hz, 1,000 Hz to 3,200 Hz, 1,500 Hz to 3,000 Hz, 1,500 Hz to 2,500 Hz, 1,600 Hz to 2,500 Hz, or 1,700 Hz to 2,300 Hz, the maximum sound absorption coefficient of the polishing pad may be 0.11 or greater, 0.12 or greater, 0.15 or greater, 0.16 or greater, 0.18 or greater, or 0.2 or greater.

[0024] Furthermore, according to KS F 2814-2, the maximum sound absorption coefficient of the polishing pad can be 0.05 or greater when measured at frequencies from 500 Hz to 1,500 Hz. For example, according to KS F 2814-2, the maximum sound absorption coefficient of the polishing pad can be 0.06 or greater, 0.07 or greater, or 0.08 or greater when measured at frequencies from 700 Hz to 1,500 Hz, 800 Hz to 1,500 Hz, 900 Hz to 1,500 Hz, or 1,000 Hz to 1,500 Hz.

[0025] According to one embodiment, the maximum sound absorption coefficient is 0.05 or greater when measured at frequencies from 1,000 Hz to 1,500 Hz, and the maximum sound absorption coefficient is 0.1 or greater when measured at frequencies from 1,500 Hz to 3,000 Hz.

[0026] According to one embodiment, based on KS F 2814-2, when the sound absorption coefficient is measured at frequencies from 500 Hz to 4,000 Hz, the polishing pad may have an absorption peak A of 0.05 or greater at frequencies from 500 Hz to 1,500 Hz, and an absorption peak B of 0.1 or greater at frequencies from 1,600 Hz to 2,500 Hz.

[0027] When the polishing pad according to one embodiment has a maximum sound absorption coefficient that satisfies the above range, it can reduce noise and vibration in a specific frequency range to minimize energy loss caused by vibration energy; therefore, it can maximize the efficiency of frictional energy, thereby producing an excellent polishing rate.

[0028] According to one embodiment, when using the polishing pad in conjunction with cerium oxide slurry to polish the silicon oxide layer of a silicon wafer, the polishing rate (removal rate) according to the following mathematical equation 1 can be 2,150 Å / min to 3,500 Å / min, 2,150 Å / min to 3,400 Å / min, or 2,200 Å / min to 3,200 Å / min. [Mathematical Equation 1] Polishing rate (Å / min) = thickness difference before and after polishing (Å) / polishing time (min)

[0029] Furthermore, when using this polishing pad in conjunction with a silicon dioxide slurry to polish the silicon oxide layer of a silicon wafer, the polishing rate according to the above mathematical equation 1 can be 3,500 Å / min to 4,500 Å / min, 3,600 Å / min to 4,300 Å / min, or 3,850 Å / min to 4,200 Å / min. Polished layer

[0030] According to one embodiment, the polishing pad includes a polishing layer. Specifically, the polishing pad includes a polishing layer comprising a polyurethane resin.

[0031] The polished layer comprises a urethane prepolymer, a foaming agent, and a curing agent. Specifically, the polyurethane resin may be formed from a composition comprising a urethane prepolymer, a foaming agent, and a curing agent.

[0032] More specifically, the polishing layer comprises a polyurethane resin, which is a reaction product of a polyurethane prepolymer, a foaming agent, and a curing agent, i.e., a cured product of a mixture of these components. Therefore, it comprises a porous polyurethane resin. Furthermore, the polishing layer may contain multiple pores formed by the foaming agent.

[0033] The thickness of the polished layer can be, for example, 0.8 mm or greater, 1 mm or greater, 1.2 mm or greater, or 1.5 mm or greater, and 5 mm or less, 3 mm or less, 2.5 mm or less, or 2 mm or less. As a specific example, the thickness of the polished layer can be from 0.8 mm to 5 mm or from 1.5 mm to 3 mm.

[0034] The specific gravity of the polished layer can be, for example, 0.6 g / cm³ or greater, 0.7 g / cm³ or greater, or 0.75 g / cm³ or greater, and 0.9 g / cm³ or less, 0.85 g / cm³ or less, or 0.8 g / cm³ or less. As a specific example, the specific gravity of the polished layer can be from 0.6 g / cm³ to 0.9 g / cm³ or from 0.7 g / cm³ to 0.9 g / cm³.

[0035] The hardness of the polished layer can be, for example, 30 Shore D or greater, 40 Shore D or greater, or 50 Shore D or greater, and 80 Shore D or less, 70 Shore D or less, 65 Shore D or less, or 60 Shore D or less. As a specific example, the hardness of the polished layer can be from 30 Shore D to 80 Shore D or from 50 Shore D to 65 Shore D.

[0036] The tensile strength of the polished layer can be, for example, 5 N / mm² or greater, 10 N / mm² or greater, or 15 N / mm² or greater, and 30 N / mm² or less, 25 N / mm² or less, or 20 N / mm² or less. As a specific example, the tensile strength of the polished layer can be from 5 N / mm² to 30 N / mm² or from 15 N / mm² to 25 N / mm².

[0037] The elongation of the polished layer can be, for example, 50% or greater, 70% or greater, 90% or greater, 106% or greater, or 120% or greater, and 300% or less, 250% or less, 200% or less, or 150% or less. As a specific example, the elongation of the polished layer can be from 50% to 300% or from 90% to 130%. This elongation can be an elongation at break.

[0038] As a specific example, the polished layer may have a hardness of 50 Shore D to 65 Shore D, a tensile strength of 15 N / mm² to 25 N / mm², and an elongation of 90% to 130%.

[0039] These pores are dispersed in the polished layer.

[0040] The average diameter of these pores can be, for example, 10 µm to 60 µm, 10 µm to 50 µm, 20 µm to 50 µm, 20 µm to 40 µm, 10 µm to 30 µm, 20 µm to 25 µm, or 30 µm to 50 µm.

[0041] Furthermore, based on the total area of ​​the polished layer, the total area of ​​the pores can be 30% to 60%, 35% to 50%, or 35% to 43%. Furthermore, based on the total volume of the polished layer, the total volume of the pores can be 30% to 70% or 40% to 60%.

[0042] The polishing layer may have grooves on its surface for mechanical polishing. These grooves may have a depth, a width, and a spacing required for mechanical polishing, and are not particularly limited thereto.

[0043] According to one embodiment, the polishing pad comprises a carbamate-based prepolymer.

[0044] Prepolymers generally refer to polymers with relatively low molecular weights, in which the degree of polymerization is adjusted to an intermediate level to facilitate product molding during manufacturing. Prepolymers can be molded alone or after reacting with another polymerizable compound. For example, prepolymers can be obtained by reacting isocyanate compounds with polyols.

[0045] The isocyanate compound used in the preparation of the carbamate prepolymer may be selected from one of the following groups: aromatic diisocyanate, aliphatic diisocyanate, alicyclic diisocyanate, or a combination thereof.

[0046] The isocyanate compound may include, for example, one selected from the group consisting of: toluene 2,4-diisocyanate (2,4-TDI), toluene 2,6-diisocyanate (2,6-TDI), naphthalene 1,5-diisocyanate, para-phenylene diisocyanate, tolidine diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and combinations thereof.

[0047] The polyol is a compound containing at least two or more hydroxyl groups (-OH) per molecule. For example, it may contain a compound selected from the group consisting of: polyether polyols, polyester polyols, polycarbonate polyols, polycaprolactone polyols, and combinations thereof.

[0048] The polyol may include, for example, those selected from the group consisting of: polytetramethylene ether glycol, polypropylene ether glycol, 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 combinations thereof.

[0049] The polyol may have a weight average molecular weight (Mw) of 100 g / mole to 3,000 g / mole. For example, the weight average molecular weight of the polyol may be 100 g / mole to 3,000 g / mole, 100 g / mole to 2,000 g / mole, or 100 g / mole to 1,800 g / mole.

[0050] According to one embodiment, the polyol may comprise a low molecular weight polyol having a weight average molecular weight (Mw) of 100 g / mole to 300 g / mole, and a high molecular weight polyol having a weight average molecular weight (Mw) of 300 g / mole to 1,800 g / mole.

[0051] Furthermore, the carbamate prepolymer may have a weight average molecular weight (Mw) of 500 g / mole to 3,000 g / mole. For example, the weight average molecular weight of the carbamate prepolymer may be 500 g / mole to 2,500 g / mole, 1,000 g / mole to 2,000 g / mole, or 1,000 g / mole to 1,500 g / mole.

[0052] According to one embodiment, the isocyanate compound used in the preparation of the carbamate-based prepolymer may comprise an aromatic diisocyanate compound, and the aromatic diisocyanate compound may, for example, comprise 2,4-toluene diisocyanate (2,4-TDI) and 2,6-toluene diisocyanate (2,6-TDI). The polyol compound used in the preparation of the carbamate-based prepolymer may comprise polytetramethylene ether glycol (PTMEG) and diethylene glycol (DEG).

[0053] According to one embodiment, the isocyanate compound used in the preparation of the carbamate-based prepolymer may comprise an aromatic diisocyanate compound and a cyclic aliphatic diisocyanate compound. For example, the aromatic diisocyanate compound may comprise 2,4-toluene diisocyanate (2,4-TDI) and 2,6-toluene diisocyanate (2,6-TDI), and the cyclic aliphatic diisocyanate compound may comprise dicyclohexylmethane diisocyanate (H12MDI). The polyol compound used in the preparation of the carbamate-based prepolymer may comprise polytetramethylene ether glycol (PTMEG) and diethylene glycol (DEG).

[0054] The isocyanate end group content (NCO%) of the carbamate-based prepolymer can be 5 wt% or more, 8 wt% or more, or 10 wt% or more, and 13 wt% or less, 12 wt% or less, or 11 wt% or less. As a specific example, the isocyanate end group content (NCO%) of the carbamate-based prepolymer can be from 8 wt% to 11 wt%, or from 9 wt% to 10 wt%.

[0055] The isocyanate end group content (NCO%) of the urethane prepolymer can be designed by comprehensively adjusting the type and content of the isocyanate and polyol compounds used to prepare the urethane prepolymer, the process conditions (such as temperature, pressure and time) in the preparation process of the urethane prepolymer, and the type and content of the additives used in the preparation of the urethane prepolymer.

[0056] If the isocyanate end group content (NCO%) of the urethane prepolymer meets the above range, then, depending on the use and purpose of a final polishing pad, the reaction rate, reaction time, and final cured structure in the subsequent reaction between the urethane prepolymer and a curing agent can be adjusted in a manner that is beneficial to polishing performance.

[0057] According to one embodiment, the isocyanate end group content (NCO%) of the urethane prepolymer can be from 8 wt% to 11 wt%, or from 9 wt% to 10 wt%.

[0058] If the NCO% of the urethane prepolymer is less than the above range, the electrical properties based on the chemically hardened structure in the polishing pad can be achieved, but the desired polishing performance in terms of polishing rate and flatness cannot be achieved, and the polishing pad life may be shortened due to excessive increase in the pad cutting rate. On the other hand, if the NCO% exceeds the above range, surface defects on the semiconductor substrate (such as scratches and chatter marks) may increase.

[0059] The foaming agent is a component used to form a porous structure in the polished layer. It may contain one selected from the group consisting of: a solid-phase foaming agent, a gas-phase foaming agent, a liquid-phase foaming agent, and combinations thereof.

[0060] According to one embodiment, the foaming agent may be a non-chlorine-based foaming agent that does not contain chlorine components. Specifically, it may contain little or no chlorine-based foaming agent components commonly used in the preparation of polishing pads, such as vinylidene chloride (VDC). For example, based on the total weight of the foaming agent, the content of the non-chlorine-based foaming agent may be 50 wt% or more, 80 wt% or more, 90 wt% or more, 95 wt% or more, 97 wt% or more, 99 wt% or more, or 99.5 wt% or more, and 100 wt% or less, or 99.5 wt% or less. As a specific example, it may be 80 wt% to 100 wt%, 90 wt% to 100 wt%, or 80 wt% to 99.5 wt%. In addition, based on the total weight of the foaming agent, the content of the chlorine-based foaming agent may be 20 wt% or less, 10 wt% or less, 5 wt% or less, 1 wt% or less, 0.5 wt% or less, or 0.3 wt% or less, and 0 wt% or more, 0.1 wt% or more, 0.5 wt% or more, as a specific example, 0 wt% to 20 wt%, 0 wt% to 1 wt%, 0 wt% to 0.5 wt%, or 0.5 wt% to 20 wt%.

[0061] The foaming agent may contain at least one of the following: a solid-phase foaming agent containing particles having a hollow structure, a liquid-phase foaming agent using a volatile liquid, and an inert gas.

[0062] As an example, the solid-phase foaming agent may contain particles with a hollow structure that have expanded and adjusted in size upon heating. The advantage of this solid-phase foaming agent is that it allows for uniform control of pore size because the agent is applied to the raw material in an expanded form and has a uniform particle size.

[0063] Furthermore, the solid-phase foaming agent may contain expandable particles. These expandable particles are particles that can expand by heating or pressurizing. The size of these expandable particles in the final polished layer can be determined by the heat or pressure applied during the preparation of the polished layer. These expandable particles are used in the raw materials in a pre-expanded particle state. The final size of these expandable particles is determined by expansion through heating or pressurization during the preparation of the polished layer.

[0064] The average particle size of the solid-phase foaming agent can be from 5 µm to 100 µm, for example, 5 µm to 50 µm, 20 µm to 50 µm, 30 µm to 48 µm, or 35 µm to 45 µm. When the particles of the solid-phase foaming agent are used in the raw material in an expanded state as described below, the average particle size of the solid-phase foaming agent can refer to the average particle size of the expanded particles themselves. When the solid-phase foaming agent is used in the raw material particles in an unexpanded state as described below, the average particle size of the solid-phase foaming agent refers to the average particle size of the particles after they have expanded through heating or pressurization during the preparation process.

[0065] Solid-phase foaming agents in the form of expandable particles may comprise a resin shell and an expansion-inducing component encapsulated within that shell. These expandable particles can form a hollow structure by vaporizing the encapsulated expansion-inducing component during the manufacturing process through heating.

[0066] For example, the housing may comprise a thermoplastic resin. The thermoplastic resin may be selected from at least one of the following: acrylonitrile copolymers, methacrylonitrile copolymers, and acrylic copolymers.

[0067] The thickness of the housing can be, for example, 0.1 µm or greater, 0.5 µm or greater, 1 µm or greater, 2 µm or greater, or 3 µm or greater, and 15 µm or less, 12 µm or less, or 10 µm or less, with 2 µm to 15 µm as a specific example.

[0068] The swelling-inducing component may comprise a compound selected from the group consisting of: hydrocarbon compounds, tetraalkylsilane compounds, and combinations thereof. Specifically, the hydrocarbon may comprise a compound selected from the group consisting of: ethane, ethylene, propane, propylene, n-butane, isobutane, n-butene, isobutene, n-pentane, isopentane, neopentane, n-hexane, heptane, petroleum ether, and combinations thereof. The tetraalkylsilane compound may comprise a compound selected from the group consisting of: tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane, trimethyl-n-propylsilane, and combinations thereof.

[0069] The solid-phase foaming agent may contain particles treated with inorganic components. In one embodiment, the solid-phase foaming agent may be a solid-phase foaming agent treated with silicon dioxide (SiO2) particles. The inorganic component treatment of the solid-phase foaming agent can prevent aggregation between multiple particles. The inorganic component-treated solid-phase foaming agent may differ from the untreated solid-phase foaming agent in terms of the chemical, electrical, and / or physical properties of the foaming agent surface.

[0070] As a specific example, the foaming agent used in a polishing pad according to one embodiment comprises a solid-phase foaming agent. The solid-phase foaming agent may comprise at least one selected from the group consisting of: acrylonitrile copolymers, methyl methacrylate copolymers, methacrylonitrile copolymers, and acrylic copolymers.

[0071] The content of the solid blowing agent relative to 100 parts by weight of the urethane-based prepolymer can be 0.1 parts by weight or more, 0.5 parts by weight or more, or 1 part by weight or more, and 5 parts by weight or less, 3 parts by weight or less, or 2 parts by weight or less. As a specific example, the content of the solid blowing agent relative to 100 parts by weight of the urethane-based prepolymer can be from 0.1 parts by weight to 5 parts by weight or from 0.5 parts by weight to 2 parts by weight.

[0072] The type and content of the solid foaming agent can be designed according to the desired pore structure and physical properties of the polished layer.

[0073] Simultaneously, a liquid-phase foaming agent can be introduced during the mixing and reaction of the prepolymer and the curing agent to form pores. This liquid-phase foaming agent does not participate in the reaction between the prepolymer and the curing agent. Furthermore, the liquid-phase foaming agent forms pores through physical evaporation caused by the heat generated during the mixing and reaction of the prepolymer and the curing agent.

[0074] This volatile liquid-phase foaming agent is liquid at 25°C; however, it does not react with isocyanate, amide, or alcohol groups. Specifically, the volatile liquid-phase foaming agent can be selected from the following group: cyclopentane, n-pentane, cyclohexane, n-butyl acetate, bis(nonafluorobutyl)(trifluoromethyl)amine; and perfluorinated compounds such as perfluorotributylamine, perfluoro-N-methylmorpholine, perfluorotripentylamine, and perfluorohexane. Commercially available perfluorinated compound products include FC-40 (3M), FC-43 (3M), FC-70 (3M), FC-72 (3M), FC-770 (3M), FC-3283 (3M), and FC-3284 (3M).

[0075] Furthermore, the foaming agent may include a gas-phase foaming agent. For example, the foaming agent may include both a solid-phase foaming agent and a gas-phase foaming agent.

[0076] The vapor-phase foaming agent may contain an inert gas. The vapor-phase foaming agent is added simultaneously with the reaction of the carbamate prepolymer and the curing agent to serve as a component for forming pores.

[0077] There are no particular restrictions on the type of inert gas, as long as it is a gas that does not participate in the reaction between the urethane prepolymer and the curing agent. For example, the inert gas may include one selected from the group consisting of: nitrogen (N2), carbon dioxide (CO2), argon (Ar), helium (He), and combinations thereof.

[0078] The type and content of the vapor-phase foaming agent can be designed according to the desired pore structure and physical properties of the polished layer.

[0079] The volume of the inert gas added can be 10% to 30% based on the total volume of the composition. Specifically, the volume of the inert gas added can be 15% to 30% based on the total volume of the composition. Specifically, the gas-phase blowing agent can be added through a predetermined feed line when the urethane prepolymer, the solid-phase blowing agent, and the curing agent are mixed. For example, the feed rate of the gas-phase blowing agent is about 0.8 L / min to about 2.0 L / min, about 0.8 L / min to about 1.8 L / min, about 0.8 L / min to about 1.7 L / min, about 1.0 L / min to about 2.0 L / min, about 1.0 L / min to about 1.8 L / min, or about 1.0 L / min to about 1.7 L / min.

[0080] The curing agent is a compound that chemically reacts with the urethane prepolymer to form the final cured structure in the polished layer. For example, it may contain amine compounds or alcohol compounds. Specifically, the curing agent may contain one selected from the group consisting of: aromatic amines, aliphatic amines, aromatic alcohols, aliphatic alcohols, and combinations thereof.

[0081] According to one embodiment, the curing agent may comprise a non-chlorine-based curing agent that does not contain chlorine components. For example, based on the total weight of the curing agent, the content of the non-chlorine-based curing agent may be 50 wt% or more, 80 wt% or more, 90 wt% or more, 95 wt% or more, 97 wt% or more, 99 wt% or more, or 99.5 wt% or more, and 100 wt% or less, or 99.5 wt% or less. As a specific example, it may be 80 wt% to 100 wt%, 90 wt% to 100 wt%, or 80 wt% to 99.5 wt%. Furthermore, based on the total weight of the curing agent, the content of the chlorine-based curing agent may be 20 wt% or less, 10 wt% or less, 5 wt% or less, 1 wt% or less, 0.5 wt% or less, or 0.3 wt% or less, and 0 wt% or more, 0.1 wt% or more, 0.5 wt% or more, as a specific example, 0 wt% to 20 wt%, 0 wt% to 1 wt%, 0 wt% to 0.5 wt%, or 0.5 wt% to 20 wt%.

[0082] The curing agent may be selected from at least one of solid-phase curing agents and liquid-phase curing agents.

[0083] The solid-phase curing agent may contain an active hydrogen group. The solid-phase curing agent may contain an amine group (-NH₂) as an active hydrogen group.

[0084] Furthermore, the solid-phase curing agent can be an ester compound containing two or more benzene rings. Specifically, the solid-phase curing agent can contain two or more ester groups in its molecule.

[0085] The weight-average molecular weight of the solid-phase curing agent can be, for example, 150 g / mole to 400 g / mole, 150 g / mole to 350 g / mole, 200 g / mole to 350 g / mole, 250 g / mole to 350 g / mole, or 300 g / mole to 350 g / mole. Furthermore, the melting point (mp) of the solid-phase curing agent can be 100°C to 150°C, 100°C to 140°C, or 110°C to 130°C.

[0086] In one embodiment, the solid curing agent comprises at least one selected from the group consisting of: 1,3-propanediol bis(4-aminobenzoate), PDPAB, 4-(4-aminobenzoyl)oxyphenyl 4-aminobenzoate, 4-(4-aminobenzoyl)oxybutyl 4-aminobenzoate, 4-[4-(4-aminobenzoyl)oxy-3-methylbutoxy]butyl 4-aminobenzoate, and methylene bis-methylanthranilate (MBNA).

[0087] The liquid-phase curing agent may contain an active hydrogen group. The liquid-phase curing agent may contain at least one active hydrogen group selected from the group consisting of amine (-NH₂), hydroxyl (-OH), carboxylic acid (-COOH), epoxy, and combinations thereof. Specifically, it may contain an amine (-NH₂).

[0088] Furthermore, this liquid-phase curing agent may contain sulfur in its molecules. Specifically, its molecules may contain two or more sulfur elements.

[0089] The weight average molecular weight of the liquid phase curing agent can be from 50 g / mole to 300 g / mole, for example from 100 g / mole to 250 g / mole, for example from 150 g / mole to 250 g / mole, for example from 200 g / mole to 250 g / mole.

[0090] Furthermore, the liquid phase curing agent can be a liquid at room temperature. Alternatively, the boiling point (bp) of the liquid phase curing agent can be from 160°C to 240°C, specifically from 170°C to 240°C, and more specifically from 170°C to 220°C.

[0091] Examples of such liquid phase curing agents include at least one selected from the group consisting of: 3,5-dimethylthio-2,6-diaminotoluene (DMTDA), 2,6-bis(methylthio)-4-methyl-1,3-benzenediamine, and N,N'-bis(sec-butylamino)diphenylmethane.

[0092] In addition to the liquid-phase curing agent and the solid-phase curing agent, the curing agent may further comprise other curing agents. These additional curing agents may be, for example, at least one of amine compounds and alcohol compounds. Specifically, the additional curing agent may comprise at least one compound selected from the group consisting of: aromatic amines, aliphatic amines, aromatic alcohols, and aliphatic alcohols.

[0093] For example, another curing agent may be selected from at least one of the following groups: diaminodiphenylmethane, diaminodiphenyl sulphone, m-xylylene diamine, isophorone diamine, ethylenediamine, diethylenetriamine, triethylenetetramine, polypropylenediamine, polypropylenetriamine, ethylene glycol, diethylene glycol, dipropylene glycol, butanediol, hexanediol, glycerin, and trimethylolpropane.

[0094] As a specific example, the curing agent may contain at least one selected from the group consisting of: 4,4'-methylenebis(2-chloroaniline), MOCA; diethyltoluenediamine (DETDA); 3,5-dimethylthio-2,6-diaminotoluene (DMTDA); and 1,3-propanediol bis(4-aminobenzoate). PDPAB), N,N'-bis(sec-butylamino)diphenylmethane, 2,6-bis(methylthio)-4-methyl-1,3-benzenediamine, 4-(4-aminobenzoyl)oxyphenyl 4-aminobenzoate, 4-(4-aminobenzoyl)oxybutyl 4-aminobenzoate, 4-[4-(4-aminobenzoyl)oxy-3-methylbutoxy]butyl 4-aminobenzoate 4-aminobenzoate), and methylene bis-methylanthranilate (MBNA).

[0095] The curing agent content relative to 100 parts by weight of the urethane-based prepolymer can be 5 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, or 20 parts by weight or more, and 50 parts by weight or less, 45 parts by weight or less, 40 parts by weight or less, 35 parts by weight or less, 30 parts by weight or less, or 25 parts by weight or less. The curing agent content relative to 100 parts by weight of the urethane-based prepolymer can be from 10 parts by weight to 40 parts by weight, more specifically from 15 parts by weight to 35 parts by weight or from 15 parts by weight to 25 parts by weight.

[0096] Furthermore, the equivalent ratio of the urethane prepolymer to the curing agent can be 1:0.5 to 2. For example, the equivalent ratio of the urethane prepolymer to the curing agent can be 1:0.5 to 1.8, 1:0.5 to 1.5, 1:0.5 to 1.0, 1:0.6 to 1.2, 1:0.8 to 1.2, or 1:0.8 to 1.0.

[0097] When the equivalent ratio of the urethane prepolymer to the curing agent meets the above-mentioned range, it can reduce noise and vibration within a specific frequency range to minimize energy loss caused by vibration energy; therefore, it can maximize the efficiency of frictional energy to improve the polishing rate.

[0098] The composition used to prepare a polished layer may further include other additives, such as a surfactant and a reaction rate controller. Names such as "surfactant" and "reaction rate controller" are arbitrary names based on the primary function of the substance. Each substance does not necessarily perform only the function defined by its name.

[0099] The surfactant is not specifically limited, as long as it can prevent pore aggregation and overlap. For example, the surfactant may include a silicone-based surfactant.

[0100] The amount of surfactant used relative to 100 parts by weight of the urethane-based prepolymer can be from 0.2 parts by weight to 2 parts by weight. Specifically, the amount of surfactant used relative to 100 parts by weight of the urethane-based prepolymer can be from 0.2 parts by weight to 1.9 parts by weight, 0.2 parts by weight to 1.8 parts by weight, 0.2 parts by weight to 1.7 parts by weight, 0.2 parts by weight to 1.6 parts by weight, 0.2 parts by weight to 1.5 parts by weight, or 0.5 parts by weight to 1.5 parts by weight. If the amount of surfactant is within the above range, the pores originating from the vapor-phase foaming agent can be stably formed and maintained in the mold.

[0101] The reaction rate control agent has the effect of promoting or retarding the reaction. Depending on the purpose, a reaction promoter, a reaction retarder, or both may be used. The reaction rate control agent may contain a reaction promoter. For example, the reaction rate control agent may be at least one reaction promoter selected from the group consisting of tertiary amine-based compounds and organometallic compounds.

[0102] Specifically, the reaction rate control agent may comprise 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, and bis(2-methylaminoethyl) ether. ether), trimethylaminoethylethanolamine, N,N,N,N,N''-pentamethyldiethylenetriamine, dimethylaminoethylamine, dimethylaminopropylamine, benzyldimethylamine, N-ethylmorpholine, N,N-dimethylaminoethylmorpholine, N,N-dimethylcyclohexylamine, 2-methyl-2-azanorbornane, dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, dioctyltin diacetate The reaction rate control agent may contain diacetate, dibutyltin maleate, dibutyltin di-2-ethylhexanoate, and dibutyltin dimercaptide. Specifically, the reaction rate control agent may include at least one selected from the group consisting of benzyldimethylamine, N,N-dimethylcyclohexylamine, and triethylamine.

[0103] The amount of the reaction rate control agent used relative to 100 parts by weight of the urethane-based prepolymer can be from 0.05 parts by weight to 2 parts by weight. Specifically, the amount of the reaction rate control agent used relative to 100 parts by weight of the urethane-based prepolymer can be: 0.05 parts by weight to 1.8 parts by weight, 0.05 parts by weight to 1.7 parts by weight, 0.05 parts by weight to 1.6 parts by weight, 0.1 parts by weight to 1.5 parts by weight, 0.1 parts by weight to 0.3 parts by weight, 0.2 parts by weight to 1.8 parts by weight, 0.2 parts by weight to 1.7 parts by weight, 0.2 parts by weight to 1.6 parts by weight, 0.2 parts by weight to 1.5 parts by weight, or 0.5 parts by weight to 1 part by weight. When the reaction rate control agent is used within the above ranges, the curing rate of the prepolymer composition can be appropriately controlled to form a polished layer with desired porosity and hardness. support layer

[0104] According to one embodiment of the present invention, the polishing pad may include a support layer.

[0105] The support layer forms a base pad and is used to support the polishing layer and absorb and disperse the impact applied to the polishing layer. Therefore, during the polishing process using this polishing pad, damage and defects to the object being polished are minimized.

[0106] The support layer may contain non-woven fabric or suede, but is not limited to these.

[0107] In one embodiment, the support layer may be a resin-impregnated nonwoven fabric. The nonwoven fabric may be a fibrous nonwoven fabric comprising at least one selected from the group consisting of: a polyester fiber, a polyamide fiber, a polypropylene fiber, and a polyethylene fiber.

[0108] The resin impregnated in the nonwoven fabric may include at least one selected from the group consisting of: polyurethane resin, polybutadiene resin, styrene-butadiene copolymer resin, styrene-butadiene-styrene copolymer resin, acrylonitrile-butadiene copolymer resin, styrene-ethylene-butadiene-styrene copolymer resin, silicone rubber resin, polyester elastomer resin, and polyamide elastomer resin.

[0109] The thickness of the support layer can be, for example, 0.3 mm or more, or 0.5 mm or more, and 3 mm or less, 2 mm or less, or 1 mm or less. As a specific example, the thickness of the support layer can be from 0.3 mm to 3 mm or from 0.5 mm to 1 mm.

[0110] The hardness of the support layer can be, for example, 50 Asker C or greater, 60 Asker C or greater, or 70 Asker C or greater, and 100 Asker C or less, 90 Asker C or less, or 80 Asker C or less. As a specific example, the hardness of the support layer can be from 50 Asker C to 100 Asker C or from 60 Asker C to 90 Asker C.

[0111] In addition, an adhesive layer can be inserted between the polishing layer (top pad) and the support layer (bottom pad).

[0112] The adhesive layer may comprise a hot-melt adhesive. The hot-melt adhesive may comprise at least one selected from the group consisting of: polyurethane resins, polyester resins, ethylene-vinyl acetate resins, polyamide resins, and polyolefin resins. Specifically, the hot-melt adhesive may be at least one selected from the group consisting of: polyurethane resins and polyester resins.

[0113] In addition, a double-sided tape can be attached under the support layer. When the polishing pad is applied to the CMP equipment, once the release paper of the double-sided tape is removed, the polishing pad is attached to the platform for use. Methods for preparing polishing pads

[0114] According to one embodiment, a method for preparing a polishing pad includes preparing a composition for the polishing pad, the composition comprising a urethane prepolymer, a foaming agent, and a curing agent; injecting the composition for the polishing pad into a mold and curing it to prepare a polishing layer; and laminating the polishing layer with a support layer.

[0115] The specific types and contents of the carbamate prepolymer, the curing agent, and the foaming agent are as illustrated above.

[0116] As a specific example, the foaming agent comprises a solid-phase foaming agent containing at least one selected from the group consisting of: acrylonitrile copolymers, methyl methacrylate copolymers, methacrylonitrile copolymers, and acrylic copolymers, and the curing agent contains at least one selected from the group consisting of: diethyltoluene diamine (DETDA), 3,5-dimethylthio-2,6-diaminotoluene (DMTDA), 1,3-propanediol bis(4-amino) Benzoate (PDPAB), N,N'-bis(secondary-butylamino)diphenylmethane, 2,6-bis(methylthio)-4-methyl-1,3-phenylenediamine, 4-(4-aminobenzoyl)oxyphenyl-4-aminobenzoate, 4-(4-aminobenzoyl)oxybutyl-4-aminobenzoate, 4-[4-(4-aminobenzoyl)oxy-3-methylbutoxy]butyl-4-aminobenzoate, and methyl methylene bis-o-aminobenzoate (MBNA).

[0117] The composition for the polishing pad can be prepared by sequentially or simultaneously mixing a carbamate prepolymer, a foaming agent, and a curing agent.

[0118] As an example, the preparation of the composition for the polishing pad can be carried out by the following steps: mixing a carbamate prepolymer with a curing agent, and then further mixing with a foaming agent, or by mixing the carbamate prepolymer with the foaming agent, and then further mixing with the curing agent.

[0119] As another example, a urethane prepolymer, a curing agent, and a foaming agent can substantially enter the mixing process simultaneously. If a foaming agent, a surfactant, and an inert gas are further added, they can also substantially enter the mixing process simultaneously.

[0120] As another example, a carbamate prepolymer, a foaming agent, and a surfactant can be mixed first, and then a curing agent or a curing agent with an inert gas can be added.

[0121] This mixing initiates a reaction between the urethane-based prepolymer and the curing agent, and uniformly disperses the blowing agent and the inert gas in the raw materials. In this case, a reaction rate control agent can intervene in the reaction between the urethane-based prepolymer and the curing agent from the beginning of the reaction to control the reaction rate. Specifically, the mixing can be carried out at a speed of 1,000 rpm to 10,000 rpm or 4,000 rpm to 7,000 rpm. Within the above speed range, it is more advantageous to uniformly disperse the inert gas and the blowing agent in the raw materials.

[0122] Furthermore, the preparation of the composition for the polishing pad can be carried out at temperatures ranging from 50°C to 150°C. If necessary, it can be carried out under vacuum defoaming conditions.

[0123] If the foaming agent contains a solid-phase foaming agent, the step of preparing the composition for the polishing pad may include: mixing the urethane prepolymer with the solid-phase foaming agent to prepare a first preliminary composition; and mixing the first preliminary composition with the curing agent to prepare a second preliminary composition.

[0124] The viscosity of the first preliminary component at about 80°C can be about 1,000 cps to about 2,000 cps, about 1,000 cps to about 1,800 cps, about 1,000 cps to about 1,600 cps, or about 1,000 cps to about 1,500 cps.

[0125] If the foaming agent comprises a gas-phase foaming agent, the step of preparing the composition for the polishing pad may include: preparing a third preliminary composition comprising the urethane-based prepolymer and the curing agent; and adding the gas-phase foaming agent to the third preliminary composition to prepare a fourth preliminary composition. In one embodiment, the third preliminary composition may further comprise a solid-phase foaming agent.

[0126] According to one embodiment, the step of preparing the polishing layer includes: preparing a mold preheated to a first temperature; injecting the composition for the polishing pad into the preheated mold and curing it; and post-curing the cured composition of the polishing pad at a second temperature higher than the preheating temperature.

[0127] According to one embodiment, the temperature difference between the first temperature and the second temperature can be from about 10°C to about 40°C, for example, from about 10°C to about 35°C or from about 15°C to about 35°C. As a specific example, the first temperature can be from about 60°C to about 100°C, from about 65°C to about 95°C, or from about 70°C to about 90°C. As a specific example, the second temperature can be from about 100°C to about 130°C, for example, from about 100°C to about 125°C or from about 100°C to about 120°C.

[0128] The step of curing the composition for the polishing pad at the first temperature can be carried out for about 5 minutes to about 60 minutes, about 5 minutes to about 40 minutes, about 5 minutes to about 30 minutes, or about 5 minutes to about 25 minutes.

[0129] At the second temperature, the post-curing step of the composition for the polishing pad that has been cured at the first temperature can be carried out for about 5 hours to about 30 hours, about 5 hours to about 25 hours, about 10 hours to about 30 hours, about 10 hours to about 25 hours, about 12 hours to about 24 hours, or about 15 hours to about 24 hours.

[0130] The subsequent step of injecting the composition for the polishing pad into a mold and allowing it to cure can be carried out under temperature conditions of 60°C to 120°C and pressure conditions of 50 kg / m² to 200 kg / m².

[0131] Furthermore, the above preparation method may further include the following steps: cutting the surface of the polishing pad obtained thereby, machining grooves on its surface, combining it with the lower component, inspection, packaging, etc. These steps can be performed in a manner conventionally used for preparing a polishing pad.

[0132] As an example, the method for preparing a polishing pad may further include processing at least one side of the polishing layer. The step of processing at least one side of the polishing layer may include: forming a groove on at least one side of the polishing layer; line turning at least one side of the polishing layer; and roughening at least one side of the polishing layer.

[0133] The grooves may include at least one of the following: concentric circular grooves spaced at a specific interval from the center of the polished layer; and radial grooves continuously extending from the center of the polished layer to its edge. The wire turning can be performed by cutting the polished layer to a specific thickness using a cutting tool. The roughening can be performed by processing the surface of the polished layer with a sanding roller. Methods for fabricating semiconductor devices

[0134] A method for fabricating a semiconductor device according to another embodiment includes using a polishing pad to polish the surface of a semiconductor substrate.

[0135] Specifically, a method for fabricating a semiconductor device may include: providing a polishing pad according to an embodiment; and rotating the polishing surface of the polishing layer and the surface of a semiconductor substrate relative to each other while they are in contact to polish the surface of the semiconductor substrate.

[0136] Figure 2 illustrates a method for fabricating a semiconductor device using a polishing pad according to an embodiment. Referring to Figure 2, when a polishing pad (100) according to an embodiment has been attached to a platform (200), a semiconductor substrate (600) serving as the object to be polished is disposed on the polishing pad (100). In this case, the surface of the semiconductor substrate (600) to be polished is in direct contact with the polishing surface of the polishing pad (100). Polishing slurry (400) can be sprayed onto the polishing pad via a nozzle for polishing. The flow rate of the polishing slurry (400) supplied through the nozzle can be selected from about 10 cm³ / min to about 1,000 cm³ / min depending on the purpose. For example, it can be from about 50 cm³ / min to about 500 cm³ / min, but is not limited thereto.

[0137] Subsequently, the semiconductor substrate (600) and the polishing pad (100) rotate relative to each other to polish the surface of the semiconductor substrate (600). In this case, the rotation direction of the semiconductor substrate (600) and the rotation direction of the polishing pad (100) can be the same or opposite. The rotation speed of the semiconductor substrate (600) and the polishing pad (100) can each be selected from about 10 rpm to about 500 rpm depending on the purpose. For example, it can be from about 30 rpm to about 200 rpm, but is not limited thereto.

[0138] The semiconductor substrate (600), mounted on a polishing head (510), is pressed against the polishing surface of the polishing pad (100) with a predetermined load to make contact with it, after which the surface of the semiconductor substrate can be polished. The load applied by the polishing head (510) to the polishing surface of the polishing pad (100) via the surface of the semiconductor substrate (600) can be selected according to the purpose in the range of about 1 gf / cm2 to about 1,000 gf / cm2. For example, it can be about 10 gf / cm2 to about 800 gf / cm2, but is not limited thereto.

[0139] In one embodiment, the semiconductor substrate (600) serving as the object to be polished may comprise an oxide layer, a uranium layer, or a composite layer thereof. Specifically, the semiconductor substrate (600) may comprise an oxide layer, a uranium layer, or a composite layer of an oxide layer and a uranium layer. The composite layer of the oxide layer and the uranium layer may be a multilayer film, wherein the uranium layer is pressed onto one side of the oxide layer, or it may be a single-layer film, wherein oxide regions and uranium regions are mixed in the single layer. When the object to be polished has this film material, and the polishing pad has the features according to this embodiment, the semiconductor device manufactured according to the method for preparing a semiconductor device may have minimal defects.

[0140] In one embodiment, the method of fabricating a semiconductor device may further include, in the step of polishing the object to be polished, supplying either a slurry for polishing an oxide layer or a slurry for polishing a tin layer; or sequentially supplying the slurry for polishing the oxide layer and the slurry for polishing the tin layer onto the polishing surface.

[0141] For example, if the semiconductor substrate, which is the object to be polished, includes an oxide layer, the method for fabricating the semiconductor device may include supplying a slurry for polishing the oxide layer. If the semiconductor substrate includes a urethane layer, the method for fabricating the semiconductor device may include supplying a slurry for polishing the urethane layer. If the semiconductor substrate includes a composite layer of an oxide layer and a urethane layer, the method for fabricating the semiconductor device may include sequentially supplying a slurry for polishing the oxide layer and a slurry for polishing the urethane layer onto the polishing surface. Here, depending on the process, the slurry for polishing the oxide layer may be supplied first, followed by the slurry for polishing the urethane layer, or the slurry for polishing the urethane layer may be supplied first, followed by the slurry for polishing the oxide layer.

[0142] In one embodiment, in order to keep the polished surface of the polishing pad (100) in a suitable polishing state, the method of preparing the semiconductor device may further include, while polishing the semiconductor substrate (600), simultaneously treating the polished surface of the polishing pad (100) with a dressing device (470).

[0143] When the chlorine content in the polishing pad according to one embodiment is adjusted to a specific range, it is possible to reduce the size of debris while maintaining the excellent physical properties and performance of the polishing pad, thereby minimizing the occurrence of defects and scratches during a CMP process. Therefore, it is feasible to efficiently fabricate high-quality semiconductor devices using this polishing pad. Modes used in this invention

[0144] The present invention will now be described in detail by way of examples. These examples are intended to further illustrate the invention, and their scope is not limited thereto. Preparation of polishing pads Example 1 (1) Preparation of carbamate prepolymers

[0145] Toluene diisocyanate (TDI), dicyclohexylmethane diisocyanate (H12MDI), polytetramethylene ether glycol (PTMEG), and diethylene glycol (DEG) were packed into a four-necked flask and then reacted at 80°C for 3 hours to obtain a carbamate prepolymer with an NCO end group (NCO%) content of 10 wt%. (2) Preparation of polishing pad

[0146] A casting machine is provided, equipped with tanks and a feeding line, for use with raw materials such as the urethane prepolymer, a curing agent, an inert gas, and a foaming agent. The urethane prepolymer, curing agent (4,4'-methylenebis(2-chloroaniline), MOCA), solid-phase foaming agent (acrylonitrile / dichloroethane, expanded cell type, average particle size: 40 µm to 42 µm), inert gas (N2), and silicone surfactant (manufacturer: Evonik) are respectively filled into the tanks. Here, 1.5 parts by weight of the solid-phase foaming agent are added relative to 100 parts by weight of the urethane prepolymer, and the urethane prepolymer and curing agent are added at a 1:1 equivalent ratio and a total rate of 10 kg / min.

[0147] Subsequently, the raw materials are agitated while being fed into the mixing head at a constant rate via their respective feed lines (mixing head speed: approximately 5,000 rpm). A mold (1,000 mm × 1,000 mm × 3 mm) is prepared and preheated at 80°C. The agitated mixture is poured into the mold and reacted to obtain a molded object in the form of a solid cake. The top and bottom of the molded object are then ground separately to obtain a polished layer for the top pad.

[0148] The polishing layer is then subjected to surface milling and groove forming steps, and is laminated together with a support layer serving as a base using a hot melt adhesive to prepare the polishing pad. In this case, a double-sided tape (model name: 442JS, manufacturer: 3M) can be attached under the support layer so that the polishing pad can be attached to the platform of the CMP equipment. Example 2

[0149] A polishing pad was prepared in the same manner as in Example 1, except that a solid foaming agent (acrylonitrile / methacrylonitrile copolymer, expanded cell type, average particle size: 40 µm to 42 µm) was used in step (2). Example 3

[0150] A polishing pad is prepared in the same manner as in Example 1, except that the equivalent ratio of the urethane prepolymer to the curing agent in step (2) is 1:0.8. Comparison Example 1

[0151] A commercially available polishing pad (model name: IK4140, manufacturer: DuPont) was used as a comparative example 1. Comparison Example 2

[0152] A commercially available polishing pad (model name: IC1010, manufacturer: DuPont) was used as a comparative example 2. Test Example 1: Sound Absorption Coefficient and Damping Ratio

[0153] The sound absorption coefficient and damping ratio of the polishing pads in Examples 1 to 3 and Comparative Examples 1 and 2 were measured according to KS F 2814-2.

[0154] Specifically, according to KS F 2814-2, a polishing pad is cut, the sample is placed inside an impedance tube, and a plane wave sound source is generated inside the tube to measure the sound pressure. Additionally, the maximum absorption coefficient is calculated according to Equation 1 below. In this case, the operating frequency range is 500 Hz to 4,000 Hz. [Equation 1] Sound absorption coefficient=(I iI r) / I i=(I a+I t) / I i

[0155] In Equation 1, when measuring the sound pressure inside the impedance tube using a cutting and polishing pad (diameter: 45 mm) according to KS F 2814-2, Ii is the intensity of the incident sound, Ir is the intensity of the reflected sound, Ia is the intensity of the absorbed sound, and It is the intensity of the transmitted sound. Test Example 2: Polishing Rate (Removal Rate)

[0156] Polishing pads for Examples 1 to 3 and Comparative Examples 1 and 2 were fixed on the platform of a CMP apparatus, with the silicon oxide layer of the silicon wafer (300 mm in diameter) facing downwards. A CMP process was then performed to measure the polishing rate.

[0157] Specifically, the silicon oxide layer was polished under a polishing load of 4.0 psi while the platform rotated at 150 rpm for 60 seconds, and a calcined cerium oxide slurry or a calcined silicon dioxide slurry was supplied to the polishing pad at a rate of 250 ml / min. After polishing, the silicon wafer was detached from the carrier, placed in a rotary dryer, washed with deionized water, and then dried with nitrogen for 15 seconds. The thickness difference of the silicon oxide layer in the dried silicon wafer before and after polishing was measured using a spectroreflectometer-type thickness gauge (model: SI-F80R, manufacturer: Keyence). The polishing rate was calculated according to the following mathematical equation 1. [Mathematical Equation 1] Polishing rate (Å / min) = thickness difference before and after polishing (Å) / polishing time (min) Test Example 3: Defect

[0158] The defect changes of the polishing pads in Examples 1 to 3 and Comparative Examples 1 and 2 were measured before and after polishing.

[0159] Specifically, the silicon wafer was polished using a CMP polisher in the same manner as in Test Example 2. After polishing, the silicon wafer was transferred to a cleaner and rinsed for 10 seconds each with 1% HF, deionized water (DIW), and 1% H₂NO₃. It was then transferred to a rotary dryer, rinsed with deionized water (DIW), and dried with nitrogen for 15 seconds. A defect measurement device (manufacturer: Tencor, model: XP+) was used to measure the change in defects in the dried silicon wafer before and after polishing. Specifically, the total number of scratches, chatter marks, pits, and residues on the wafer surface was measured. [Table 1] sound absorption coefficient Polishing rate (Å / min) Defects / Scratches (count) Silicon dioxide slurry Cerium oxide slurry Example 1 (Ex.1) 0.200 2,295.0 3,906.9 7 Example 2 (Ex.2) 0.121 2,317.8 3,938.7 9 Example 3 0.102 2,220.7 3,908.7 9 Compare Example 1 (C.Ex.1) 0.088 2,109.0 3,800.4 13 Compare Example 1 (C.Ex.2) 0.099 2,093.7 3,484.7 12

[0160] As can be seen from Table 1 above, the polishing pads of Examples 1 to 3 exhibit excellent sound absorption characteristics, significantly fewer defects and scratches, and excellent polishing rates. Specifically, in the frequency range of 500 Hz to 4,000 Hz, the polishing pads of Examples 1 to 3 have a maximum sound absorption coefficient of 0.1 or greater, indicating that their sound absorption characteristics are superior compared to the conventional polishing pads of Comparative Examples 1 and 2 (see Figure 1). Furthermore, in the frequency range of 500 Hz to 4,000 Hz, the polishing pads of Examples 1 to 3 have a maximum sound absorption coefficient of 0.1 or greater; therefore, compared to Comparative Examples 1 and 2, they minimize energy loss caused by thermal or vibrational energy during CMP polishing, thereby producing excellent polishing rates. They also exhibit significantly fewer defects and scratches.

[0161] 100: Polishing Pad 200: Platform 300: Dresser 400: Polishing slurry 510: Polishing head 520: Carrier 600: Semiconductor assembly, semiconductor substrate (wafer)

Claims

1. A polishing pad comprising a polishing layer, wherein the polishing layer comprises a urethane prepolymer, a foaming agent, and a curing agent, and, according to Equation 1, has a maximum sound absorption coefficient of 0.1 or greater when measured at frequencies from 500 Hz to 4,000 Hz: [Equation 1] Sound absorption coefficient = (Ii - Ir) / Ii = (Ia + It) / Ii In Equation 1, when the polishing pad (diameter: 45 mm) is cut according to KS F 2814-2 to measure the sound pressure within an impedance tube, Ii is the intensity of the incident sound, Ir is the intensity of the reflected sound, Ia is the intensity of the absorbed sound, and It is the intensity of the transmitted sound; wherein, When using this polishing pad with cerium oxide slurry to polish the silicon oxide layer of a silicon wafer, the polishing rate is 2,150 Å / min to 3,500 Å / min according to the following mathematical equation 1, and when using this polishing pad with silicon dioxide slurry to polish the silicon oxide layer of a silicon wafer, the average polishing rate is 3,500 Å / min to 4,500 Å / min according to the following mathematical equation 1: [Mathematical Equation 1] Polishing rate (Å / min) = thickness difference before and after polishing (Å) / polishing time (min).

2. The polishing pad of claim 1, wherein the maximum absorption coefficient is 0.05 or greater when measured at frequencies from 1,000 Hz to 1,500 Hz, and the maximum absorption coefficient is 0.1 or greater when measured at frequencies from 1,500 Hz to 3,000 Hz.

3. The polishing pad of claim 1, wherein the foaming agent comprises a solid foaming agent, and the solid foaming agent comprises at least one selected from the group consisting of: acrylonitrile copolymers, methyl methacrylate copolymers, methacrylonitrile copolymers, and acrylic copolymers.

4. The polishing pad of claim 3, wherein the solid foaming agent has an average particle size of 5 µm to 100 µm and has a content of 0.1 parts by weight to 5 parts by weight relative to 100 parts by weight of the urethane prepolymer.

5. The polishing pad of claim 1, wherein the curing agent comprises at least one selected from the group consisting of: 4,4'-methylenebis(2-chloroaniline) (MOCA), diethyltoluenediamine (DETDA), 3,5-dimethylthio-2,6-diaminotoluene (DMTDA), 1,3-propanediol bis(4-aminobenzoate) (PDPAB), N,N'-bis(secondary-butylamino)diphenylmethane, 2,6-bis(methylthio)-4-methyl-1,3-phenylenediamine, 4-(4-aminobenzoyl)oxyphenyl-4-aminobenzoate, 4-(4-aminobenzoyl)oxybutyl-4-aminobenzoate, 4-[4-(4-aminobenzoyl)oxy-3-methylbutoxy]butyl-4-aminobenzoate, and methyl methylenebis-o-aminobenzoate (MBNA).

6. The polishing pad of claim 1, wherein the curing agent comprises 5 to 50 parts by weight relative to 100 parts by weight of the urethane prepolymer.

7. The polishing pad of claim 1, wherein the equivalent ratio of the urethane prepolymer to the curing agent is 1:0.5 to 2.

8. The polishing pad of claim 1, wherein the polishing layer has a hardness of 50 Shore D to 65 Shore D, a tensile strength of 15 N / mm² to 25 N / mm², and an elongation of 90% to 130%.

9. A method of fabricating a semiconductor device, comprising polishing the surface of a semiconductor substrate using a polishing pad as claimed in claim 1.

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