Polishing pad and method for manufacturing the same

Abstract

To provide a polishing pad excellent in starting performance and a method for manufacturing the same.SOLUTION: A polishing pad comprises a resin sheet having a plurality of tear-shaped foams and a polishing surface for polishing an article to be polished. When a free induction attenuation signal (FID) acquired by a pulse NMR is subtracted in order from a longer component of spin-spin relaxation time T2s by a least square method and waveform-separated, thereby divided into three components of an amorphous phase, an interface phase, and a crystal phase in order from the longer component of spin-spin relaxation time T2s, in the resin sheet has ΔT2s,15min, which is a difference between relaxation time T2s,15min of the amorphous phase component of the resin sheet acquired from the measuring result of the relaxation time using the pulse NMR after dressing of the polishing pad for 15 minutes and relaxation time T2s,dry of the amorphous phase component of the resin sheet acquired from the measuring result of the relaxation time using the pulse NMR in a dry state before the dressing of the polishing pad, of 0.35ms or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polishing pad and a method for manufacturing the same, and more particularly to a polishing pad for polishing silicon, hard disks, mother glass for liquid crystal displays, and semiconductor devices, and a method for manufacturing the same. [Background technology]

[0002] Since flatness is required for the surfaces of materials such as optical materials, semiconductor devices, hard disks, and glass substrates, a free abrasive polishing method using a polishing pad is used. The free abrasive method is a method of polishing the processed surface of an object by supplying a slurry (polishing liquid) containing abrasive grains between the polishing pad and the object to be polished. Polishing of semiconductor devices is carried out using the so-called chemical mechanical polishing (CMP) method, which uses the chemical components contained in the polishing slurry to enhance the mechanical polishing (surface removal) effect caused by the relative movement of the abrasive and the object to be polished, thereby achieving a fast and smooth polished surface.

[0003] Polishing pads are broadly divided into two types: those with a polishing layer made of a resin sheet formed by a wet film-forming method (soft polishing pads), and those made by curing a prepolymer with a curing agent to form polyurethane (dry method) and then slicing it (hard polishing pads).Soft polishing pads have numerous teardrop-shaped macro bubbles in the resin sheet, making them softer than hard polishing pads and suitable for finish polishing of workpieces. Hard polishing pads are harder than soft polishing pads and have a superior polishing rate (amount polished per hour), so they are often used for the initial polishing of the workpiece. On the other hand, polishing pads with a polishing layer made of a resin sheet formed by a wet film-forming method are soft. Polishing pads used for polishing semiconductor devices and other devices are increasingly required to eliminate defects and achieve flatter surfaces, and soft polishing pads are increasingly being used, especially in the final polishing process.

[0004] Since soft polishing pads are used for finish polishing, polishing pads that are less likely to scratch the surface of the workpiece during polishing are required. Patent Document 1 describes that in order to solve the problem of scratches caused by the film-forming aid remaining in the urethane resin formed by the wet film-forming method even after solidification treatment, a compound having an alcoholic hydroxyl group is used as the film-forming aid, thereby reducing the amount of film-forming aid remaining in the polishing pad after wet film formation.

[0005] In addition, the polyurethane resin constituting the polishing pad is generally hydrophobic, so it does not mix well with the slurry, resulting in the problem that the slurry does not easily remain on the polishing pad. To address this problem, Patent Documents 2 and 3 describe a method for improving the wettability of the polishing slurry to the polishing pad by using a urethane prepolymer composed of a diol and a polyisocyanate having pendant ethylene oxide repeating units on the side chain, thereby introducing hydrophilic ethylene oxide repeating units into the surface of the urethane resin polishing pad. Furthermore, Patent Document 4 describes a method for improving the defect rate without reducing the planarization efficiency by polymerizing a urethane resin using a polyol blend containing a hydrophilic portion that is a repeating unit of polyethylene glycol or ethylene oxide. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2023-44910 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-63323 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-63324 [Patent Document 4] Japanese Patent Application Publication No. 2018-43342 Summary of the Invention [Problem to be solved by the invention]

[0007] In CMP technology, it is necessary to stabilize the polishing rate from the viewpoint of improving productivity and yield. In particular, since the polishing rate at the start of polishing is smaller than the polishing rate in the steady state, it is necessary to further shorten the time required for dummy polishing (start-up processing time) until the polishing rate becomes almost constant. However, although the polishing pad in Patent Document 1 is a polishing pad with a resin sheet formed by a wet film-forming method as the polishing layer, the problem of residual film-forming aids causing agglomerates that cause scratches is addressed by aiming to reduce scratches by not leaving any film-forming aids behind, and the problem of start-up processing time is not recognized as an issue. The polishing pads in Patent Documents 2 and 3 are hard polishing pads formed by curing a prepolymer having ethylene oxide repeating units in its side chains through a reaction with a curing agent (chain extender), and are not polishing pads that include a resin sheet obtained by a wet film-forming method. Furthermore, Patent Documents 2 and 3 merely measure the contact angle when water is dropped onto the resin surface, and do not address the issue of shortening the rise time. Similarly, the polishing pad of Patent Document 4 is a dry polishing pad formed by curing a prepolymer containing a urethane bond-containing polyisocyanate compound through a reaction with a curing agent (chain extender), and is not a polishing pad containing a resin sheet obtained by a wet film-forming method. Furthermore, the polishing pad of Patent Document 4 aims to improve the defect rate without reducing the planarization efficiency, and does not address the issue of shortening the rise time. Thus, none of Patent Documents 1 to 4 recognizes the problem of the rise time in a polishing pad having a polishing layer that is a resin sheet formed by a wet film-forming method. The present invention has been made in consideration of the above-mentioned problems, and aims to provide a polishing pad having excellent stand-up properties in a polishing pad having a polishing layer made of a resin sheet formed by a wet film-forming method, and a method for manufacturing the same. [Means for solving the problem]

[0008] As a result of intensive research, the present inventors have discovered that a polishing pad including a resin sheet having a plurality of teardrop-shaped bubbles as a polishing layer has a relaxation time T of the amorphous phase component of the resin sheet obtained from the relaxation time measurement results using pulse NMR after dressing the polishing pad for 15 minutes. 2s,15min and the relaxation time T of the amorphous phase component of the resin sheet obtained from the measurement results of the relaxation time using pulse NMR in a dry state before dressing the polishing pad. 2s,dry The difference between 2s、15min However, they found that a polishing pad with a rise time of 0.35 ms (milliseconds) or more has excellent rise time, and completed the present invention. The present invention may include the following configurations. [1] A polishing pad including a resin sheet having a plurality of teardrop-shaped bubbles and a polishing surface for polishing an object to be polished, The free induction decay signal (FID) obtained by pulsed NMR was calculated by the least squares method to estimate the spin-spin relaxation time T 2s By subtracting the longest component and separating the waveform, the spin-spin relaxation time T 2s When the resin sheet is divided into three components, namely, an amorphous phase, an interface phase, and a crystalline phase, in order from the longest to the longest, the relaxation time T of the amorphous phase component of the resin sheet obtained from the measurement result of the relaxation time using pulse NMR after dressing the polishing pad for 15 minutes is 2s,15min and the relaxation time T of the amorphous phase component of the resin sheet obtained from the measurement results of the relaxation time using pulse NMR in a dry state before dressing the polishing pad. 2s,dry The difference between 2s、15min is 0.35 ms or more. [2] The polishing pad according to [1], wherein the resin sheet is a polyurethane sheet. [3] The relaxation time T of the amorphous phase component obtained from the relaxation time measurement results using pulse NMR when the polishing pad is dressed at each of five time points of 15 minutes, 30 minutes, 60 minutes, 90 minutes, and 120 minutes. 2s The SD(T 2s,15-120min) is less than 0.05 ms. [4] The relaxation time T of the amorphous phase component obtained from the measurement result of the relaxation time using pulse NMR after dressing the polishing pad for 2 hours. 2s,120min and the relaxation time T of the amorphous phase component obtained from the measurement results of the relaxation time using pulse NMR in a dry state before dressing the polishing pad. 2s,dry The difference between 2s,120min The polishing pad according to any one of [1] to [3], wherein the polishing time is 0.35 ms or more. [5] A polishing pad according to any one of [1] to [4], wherein, when the polishing pad is dressed, the dressing time required for the relaxation time value of the non-crystalline phase component obtained from the relaxation time measurement results using pulse NMR to become 0.8 ms or more is 15 minutes or less. [Effects of the Invention]

[0009] According to the present invention, a polishing pad having excellent build-up properties can be obtained. It is also possible to obtain a polishing pad in which the occurrence of defects such as scratches on the surface of the workpiece to be polished is reduced. It is also possible to obtain a polishing pad having a high removal rate. [Brief explanation of the drawings]

[0010] [Figure 1] This is a scanning electron microscope image of a resin sheet (polyurethane sheet) containing multiple teardrop-shaped bubbles formed by a wet film-forming method and multiple nearly spherical microbubbles that are smaller than the teardrop-shaped bubbles, and which are interconnected. [Figure 2] FIG. 1 is a diagram showing a time-free induction decay signal curve measured by pulsed NMR, and a curve obtained by waveform separation of the curve into an amorphous phase (L component), an interface phase (I component), and a crystalline phase (S component) using the least squares method based on the difference in spin-spin relaxation time. [Figure 3]FIG. 1 is a graph showing the change in relaxation time of the amorphous phase component with respect to the dressing time when the spin-spin relaxation time was measured by pulse NMR after dressing the polishing pads of Examples 1 to 3 and Comparative Examples 1 and 2. [Figure 4] FIG. 1 is a graph showing the change in the proportion of amorphous phase components with respect to the dressing time when the polishing pads of Examples 1 to 3 and Comparative Examples 1 and 2 were dressed and then the spin-spin relaxation time was measured by pulse NMR. [Figure 5] FIG. 1 is a graph showing the change in polishing rate with respect to the number of processed silicon wafers when polishing silicon wafers with a TEOS (tetraethoxysilane) film using the polishing pads of Examples 1 to 3 and Comparative Examples 1 and 2. [Figure 6] FIG. 1 is a graph showing the change in polishing rate with respect to the number of processed silicon wafers when polishing silicon wafers with a TEOS (tetraethoxysilane) film using the polishing pads of Comparative Examples 1 and 2. [Figure 7] FIG. 1 is a graph showing the change in polishing rate with respect to the number of processed silicon wafers when polishing silicon wafers with a TEOS (tetraethoxysilane) film using the polishing pads of Examples 1 and 2 and Comparative Example 1. [Figure 8] FIG. 10 is a graph showing the change in polishing rate with respect to the number of processed silicon wafers when polishing silicon wafers with a TEOS (tetraethoxysilane) film using the polishing pads of Example 3 and Comparative Example 2. [Figure 9] FIG. 1 is a graph showing the change in defect count with respect to the number of processed silicon wafers when polishing Cu film-coated wafers using the polishing pads of Examples 1 to 3 and Comparative Example 1. [Figure 10] FIG. 2 is a diagram showing the results of measuring the components contained in the resin sheet of Comparative Example 1 by gas chromatography mass spectrometry (GC-MS). [Figure 11] FIG. 10 is a diagram showing the results of measuring the components contained in the resin sheet of Example 3 by gas chromatography mass spectrometry (GC-MS). DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described. <<Polishing pads>> The polishing pad of the present invention is a polishing pad comprising a resin sheet having a plurality of teardrop-shaped bubbles. The polishing pad of the present invention is used for polishing optical materials, semiconductor wafers, semiconductor devices, hard disk substrates, etc., and is particularly suitable for chemical mechanical polishing (CMP) of devices having an oxide layer or a metal layer such as copper formed on a semiconductor wafer, particularly for finish polishing. The resin sheet having a plurality of teardrop-shaped bubbles is formed by a wet film-forming method. The term teardrop-shaped bubbles refers to bubbles formed inside the resin sheet by the wet film-forming method (bubbles that are anisotropic and have a structure in which the diameter increases from the top of the resin sheet (the side in contact with the workpiece) to the bottom), and is used to distinguish them from the approximately spherical bubbles formed by a dry molding method. The resin sheet having a plurality of teardrop-shaped bubbles of the present invention can be rephrased as a resin sheet formed by a wet film-forming method. The wet film-forming method is a method in which a resin to be formed into a film is dissolved in an organic solvent, the resin-containing solution is applied to a sheet-like substrate, and the solution is then passed through a coagulation liquid in which the organic solvent dissolves but the resin does not, thereby replacing the organic solvent, coagulating the resin, and drying the resin to form a foamed layer. Usually, when a resin sheet is produced by the wet film-forming method, a plurality of approximately teardrop-shaped macrobubbles (teardrop-shaped bubbles) are generated inside the resin sheet. The dry molding method is a method of forming polyurethane by reacting a prepolymer containing a urethane bond-containing polyisocyanate compound with a curing agent and a foaming agent to harden the prepolymer.Then, the foam is sliced ​​into sheets to form a polishing pad.The polishing pad with a hard polishing layer produced by this dry molding method has relatively small, approximately spherical bubbles inside the foam, so that the polishing surface of the polishing pad formed by slicing has openings (apertures) that can hold slurry during polishing. A resin sheet having a plurality of teardrop-shaped bubbles may also include a plurality of interconnected bubbles, which include teardrop-shaped bubbles and a plurality of substantially spherical microbubbles smaller than the teardrop-shaped bubbles, which are interconnected with each other (see FIG. 1). In the present specification and claims, the resin sheet is preferably a polyurethane sheet. A polyurethane sheet refers to a sheet containing polyurethane resin as the main component (50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 85% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more of the total resin constituting the resin sheet is polyurethane resin, and the polyurethane resin may be 100% by mass), and is clearly distinguished from sheets containing other resins (such as silicone resin) as the main component. In addition, the resin sheet preferably does not contain a fluorine-based water repellent having a polyfluoroalkyl group, more preferably does not contain a fluorine-based water repellent, more preferably does not contain a fluorine-based water repellent, a silicone-based water repellent, or a hydrocarbon-based water repellent, and preferably does not contain a water repellent. Examples of water repellents include those described in JP 2022-156160 A. In this specification and claims, the term "polishing layer" refers to a layer having a surface (polishing surface) that comes into contact with an object to be polished when polishing the object, such as a semiconductor device. The polishing pad of the present invention may have another layer, such as a cushion layer, on the side of the polishing layer opposite the polishing surface.

[0012] <<Polishing pad of first embodiment>> The polishing pad of the first aspect of the present invention is a polishing pad including a resin sheet having a plurality of teardrop-shaped bubbles and a polishing surface for polishing an object to be polished, and the free induction decay signal (FID) obtained by pulsed NMR is calculated by the least squares method to obtain the spin-spin relaxation time T 2s By subtracting the longest component and separating the waveform, the spin-spin relaxation time T 2s When the resin sheet is divided into three components, namely, an amorphous phase, an interface phase, and a crystalline phase, in order from the longest to the longest, the relaxation time T of the amorphous phase component of the resin sheet obtained from the measurement result of the relaxation time using pulse NMR after dressing the polishing pad for 15 minutes is 2s,15minand the relaxation time T of the amorphous phase component of the resin sheet obtained from the measurement results of the relaxation time using pulse NMR in a dry state before dressing the polishing pad. 2s,dry The difference between 2s、15min is 0.35 ms or more. In this specification, the conditioning of the polishing pad for measuring the relaxation time using pulsed NMR can be carried out using a dresser and a slurry under the following conditioning conditions.

[0013] (Dressing conditions) Polishing pad rotation speed: 30 rpm Slurry: Colloidal silica aqueous solution Slurry flow rate: 80 mL / min Dresser rotation speed: 30 rpm Dressing pressure: 10N. To explain the dressing process in detail, first, the polishing pad is placed on the polishing platen of the polishing machine. Using the slurry and dresser, the dresser and polishing pad are rotated at a dressing pressure of 10 N, a dresser rotation speed of 30 rpm, and a polishing pad rotation speed of 30 rpm. The polishing pad is dressed by dripping the slurry onto the center of rotation of the polishing pad at a rate of 80 mL per minute. As the dresser, for example, a diamond dresser manufactured by 3M, model number "A188" can be used. The slurry may be, for example, an aqueous colloidal silica solution, such as a colloidal silica stock solution (silica concentration 14 to 16 wt%):water=1:3 (mass ratio).

[0014] In this specification, a polishing pad in a "dry state before dressing" refers to a polishing pad that has not been dressed and has not been exposed to liquids such as water or slurry. Preferably, a polishing pad in a "dry state before dressing" refers to a polishing pad that has not been dressed and has not been exposed to liquids such as water or slurry, and has been left for 48 hours under conditions of a temperature of 25°C and a relative humidity of 50%.

[0015] (Pulsed NMR) Pulsed NMR, also known as TD-NMR, is measured using a pulsed NMR measurement device using the solid echo method, with a 90° pulse of 0.5 seconds, a repetition time of 4 seconds, 128 accumulations, and a temperature of 40°C. The solid echo method is already well known, so we will not go into detail here, but it is primarily used to measure samples with short relaxation times, such as glassy and crystalline polymers. This method, which seemingly eliminates dead time, uses the 90°x-τ-90°y pulse method, in which two 90° pulses are applied with a 90° phase difference. When a 90° pulse is applied in the x-axis direction, a free induction decay (FID) signal is observed after the dead time. If a second 90° pulse is applied in the y-axis direction at time τ, when the FID signal does not decay, the magnetization orientation aligns and an echo appears at time t = 2τ. The resulting echo can be approximated to the FID signal after a 90° pulse. Methods for analyzing the relationship between physical properties, phase-separated structure, and composition from the results of pulsed NMR analysis are already well known. The free induction decay (FID) signal obtained by pulsed NMR can be separated into three components by subtracting the component with the longest spin-spin relaxation time T2 using the least-squares method and waveform separation. The component with the longest relaxation time is defined as the amorphous phase, which has high mobility; the component with the shortest relaxation time is defined as the crystalline phase, which has low mobility; and the intermediate component is defined as the interfacial phase (if it is difficult to separate the interfacial phase and the amorphous phase, it is analyzed as the interfacial phase). The amount (abundance ratio) of each component can be determined using a calculation formula using Gaussian and Lorentzian functions (see, for example, "Analysis of the Phase-Separated Structure of Polyurethane Resin by Solid-State NMR (High-Resolution NMR and Pulsed NMR)" (DIC Technical Review No. 12, pp. 7-12, 2006)).

[0016] (spin-spin relaxation time) In the present invention, the relaxation time and proportion of each component of the crystalline phase, interface phase, and amorphous phase in a resin sheet can be measured using pulse NMR as follows. First, a 1-cm-diameter glass tube is filled with four pieces of sample, each approximately 20 × 10 mm square. The sample is then placed in a magnetic field, and the relaxation behavior of the macroscopic magnetization after a high-frequency pulse magnetic field is applied is measured. The free induction decay (FID) signal is obtained as shown in Figure 2 (horizontal axis: time (msec), vertical axis: free induction decay signal). The initial value of the FID signal obtained is proportional to the number of protons in the sample. If the sample contains three components, the FID signal appears as the sum of the response signals of the three components. However, because the components in the sample have different mobilities, the decay rates of the response signals differ between the components, resulting in different spin-spin relaxation times, T2. Therefore, the sample can be separated into three components using the least-squares method. The components with the longest spin-spin relaxation times, T2, are the amorphous phase, the interface phase, and the crystalline phase, respectively (see Figure 2). The amorphous phase is a component with high molecular mobility, the crystalline phase is a component with low molecular mobility, and the intermediate component is the interface phase. After the FID signal is obtained, fitting is performed to separate the FID signal into signals for three components with different kinetics (crystalline phase component, interface phase component, and amorphous phase component). Fitting is performed using BRUKER's analysis software "TD-NMR Analyzer," and the obtained relaxation curve is fitted using the following calculation formula 1 according to the product manual. The ratio and relaxation time of each component are determined from the curve derived from the three components obtained by measurement. The fitting is performed in two stages. First, in the first stage, the FID signal in the measurement time range of 0.15-2.0 ms is fitted to a single component (i.e., the amorphous phase component only), and the FID signal of the single component (amorphous phase component) in the 0-2.0 ms range is calculated (the FID signal of the single component (amorphous phase component) in the 0-0.15 ms range is also determined by fitting). Next, in the second step, the waveform obtained in the first fitting step is subtracted from the FID signal of all three components in the measurement time interval of 0-2.0 ms, and the waveform after subtraction is fitted as two components (i.e., the crystalline phase and the interface phase, which are the two components excluding the amorphous phase component from the three components of the crystalline phase, interface phase, and amorphous phase). This allows the FID signals of the crystalline phase and the interface phase to be separated from each other. In this embodiment, fitting is performed with the Weibull coefficients W(1)=2.0, W(2)=1.0, and W(3)=1.0 in ascending order of relaxation time T2. In the first step, the FID signal in the measurement time range of 0.15-2.0 ms was fitted using only the amorphous phase component because the amorphous phase component has a longer relaxation time than the crystalline phase component and the interface phase component (see Figure 2), and the FID signal with a measurement time of 0.15 ms or longer is thought to be derived from the amorphous phase component. In the second step, the FID signals of only the crystalline phase and interface phase are obtained by subtracting the waveform obtained in the first step. Therefore, by fitting using these two components, the waveforms of the crystalline phase component and the interface phase component can be determined more accurately. This analysis method is an analysis method that can obtain the characteristics of amorphous phase components with long relaxation times more clearly by dividing the number of components used in fitting and the analysis interval.

[0017] formula 1 TIFF2025156108000001.tif2073 where I(t) represents the fitting intensity at time t, and a _i (n) represents the intensity factor of the nth component, T2(n) represents the relaxation time of the nth component, and W(n) represents the Weibull modulus of the nth component.

[0018] (ΔT 2s、15min ) In the first aspect of the present invention, the relaxation time T of the amorphous phase component of the resin sheet obtained from the measurement result of the relaxation time using pulse NMR after dressing the polishing pad for 15 minutes. 2s,15min and the relaxation time T of the amorphous phase component of the resin sheet obtained from the measurement results of the relaxation time using pulse NMR in a dry state before dressing the polishing pad. 2s,dry The difference between 2s、15min Use a resin sheet with a ΔT of 0.35 ms or more. 2s、15min is preferably 0.36 ms or more, more preferably 0.38 ms or more, and even more preferably 0.40 ms or more. By using a resin sheet having the above properties, a polishing pad with excellent start-up processability can be obtained. The reason why the start-up processability can be improved by using a resin sheet having the above-mentioned properties is not entirely clear, but it can be assumed as follows. 1 The spin-spin relaxation time T2 observed by H-pulse NMR is fastest for the crystalline phase, followed by the interface phase and the amorphous phase (hence, the relaxation time of the amorphous phase is the slowest). The interface phase has a faster relaxation time than the amorphous phase, and is considered to be an amorphous phase with restricted mobility. When the slurry is applied to the polishing surface of the polishing pad, water molecules are bound to some of the molecular chains that were restricted as the interface phase before the slurry was dropped, and it is thought to become an amorphous phase component with high mobility. Therefore, ΔT 2s、15min It is believed that by having the value of (a) be within the above range, many of the portions that were interfacial phase components before the dropping of the slurry bond with water molecules derived from the slurry and become amorphous phase components in a short time after the dropping of the slurry, and the slurry becomes compatible with the resin sheet (penetrates into the resin sheet). This is thought to improve start-up processability. Furthermore, by using a resin sheet having the above properties, defects such as scratches on the surface of the workpiece are less likely to occur, and a high polishing rate can be achieved. ΔT 2s、15min There is no particular limit to the upper limit, and it may be 0.60 ms or less, 0.55 ms or less, or 0.50 ms or less.

[0019] (ΔT 2s、120min ) In the first aspect of the present invention, the relaxation time T of the amorphous phase component of the resin sheet obtained from the measurement results of the relaxation time using pulse NMR after dressing the polishing pad for 120 minutes. 2s,120min and the relaxation time T of the amorphous phase component of the resin sheet obtained from the measurement results of the relaxation time using pulse NMR in a dry state before dressing the polishing pad. 2s,dry The difference between 2s、120min It is preferable to use a resin sheet having a ΔT of 0.35 ms or more. 2s、120minis more preferably 0.36 ms or more, even more preferably 0.38 ms or more, and even more preferably 0.40 ms or more. ΔT 2s、120min Within the above range, a polishing pad with excellent start-up processability is easily obtained. ΔT 2s、120min There is no particular limit to the upper limit, and it may be 0.60 ms or less, 0.55 ms or less, or 0.50 ms or less.

[0020] (SD(T 2s,15-120min )) In the first aspect of the present invention, the relaxation time T of the amorphous phase component obtained from the relaxation time measurement results using pulse NMR when the polishing pad is dressed at each of five time points of 15 minutes, 30 minutes, 60 minutes, 90 minutes, and 120 minutes. 2s The SD(T 2s,15-120min ) is preferably less than 0.05 ms. 2s,15-120min ) is more preferably 0.04 ms or less, even more preferably 0.03 ms or less, even more preferably 0.025 ms or less, even more preferably 0.018 ms or less, and even more preferably 0.015 ms or less. SD(T 2s,15-120min ) is within the above range, a polishing pad with excellent start-up processability is likely to be obtained. SD(T 2s,15-120min ) can be calculated using the following formula 2. Formula 2: JPEG2025156108000002.jpg31152

[0021] (Amorphous phase component ratio (%)) In this specification, the abundance ratios of the crystalline phase, the interface phase (intermediate phase), and the amorphous phase are sometimes referred to as A1, A2, and A3 (%), respectively. Generally, the lower the proportion of the amorphous phase, the harder the urethane. Furthermore, the smaller the interface phase, the more clearly phase-separated the crystalline phase and the amorphous phase, and the more likely it is to have elastic properties that are less susceptible to distortion. Conversely, the more interface phase, the less clearly phase-separated the crystalline phase and the amorphous phase, and the more likely it is to have delayed elastic properties. In the polishing pad of the first aspect of the present invention, the proportion of amorphous phase components obtained from the results of measuring the relaxation time using pulse NMR after dressing the polishing pad for 15 minutes is preferably 55% or more (unit: mol%). The proportion of amorphous phase components is more preferably 58% or more, even more preferably 60% or more, and even more preferably 62% or more. There is no particular upper limit to the proportion of amorphous phase components, and it may be 75% or less, 70% or less, 68% or less, or 65% or less. In the polishing pad of the first aspect of the present invention, the proportion of amorphous phase components obtained from the relaxation time measurement using pulse NMR after dressing the polishing pad for 30 minutes is preferably 58% or more, more preferably 60% or more, and even more preferably 62% or more. There is no particular upper limit to the proportion of amorphous phase components, and it may be 75% or less, 70% or less, 68% or less, or 65% or less.

[0022] In the polishing pad of the first aspect of the present invention, when the polishing pad is dressed, the dressing time required for the relaxation time of the amorphous phase component, as measured by pulse NMR, to reach 0.8 ms or more is preferably 15 minutes or less. The dressing time required for the relaxation time of the amorphous phase component to reach 0.8 ms or more is more preferably 10 minutes or less, and even more preferably 5 minutes or less. When the dressing time required for the relaxation time of the amorphous phase component to reach 0.8 ms or more is within the above range, a polishing pad with excellent start-up processability is easily obtained.

[0023] <Polyurethane resin> The resin sheet preferably contains a polyurethane resin. There are no particular limitations on the type of polyurethane resin, and it may be selected from various polyurethane resins depending on the intended use. For example, a polyester-based, polyether-based, or polycarbonate-based polyurethane resin may be used. Examples of polyester resins include polymers of polyester polyols such as ethylene glycol or butylene glycol (e.g., 1,4-butanediol) and adipic acid, and diisocyanates such as diphenylmethane-4,4'-diisocyanate. In addition to the above, polyols such as butanediol, trimethylolpropane, and triethanolamine may also be added to form polymers. Among these, the polyester-based polyurethane resin is preferably a polyurethane resin that is a condensate of a polyester polyol obtained by dehydration condensation of 1,4-butanediol and adipic acid, 1,4-butanediol, trimethylolpropane, and 4,4'-diphenylmethane diisocyanate (MDI). The molar ratio of 1,4-butanediol to trimethylolpropane is preferably 7:3 to 3:7, more preferably 7:3 to 5:5, and even more preferably 6:4. Examples of polyether resins include polymers of polyether polyols such as polytetramethylene ether glycol and polypropylene glycol with isocyanates such as diphenylmethane-4,4'-diisocyanate. Examples of polycarbonate resins include polymers of polycarbonate polyol and isocyanates such as diphenylmethane-4,4'-diisocyanate. These resins may be commercially available resins such as those manufactured by DIC under the trade name "Crisvon," those manufactured by Sanyo Chemical Industries, Ltd. under the trade name "Sunprene," and those manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd. under the trade name "Rezamin," or resins having the desired properties may be manufactured by the manufacturer.

[0024] (modulus) Modulus is an index that indicates the hardness of a resin, and is the value obtained by dividing the load applied when an unfoamed resin sheet is stretched 100% (stretched to twice its original length) by the cross-sectional area (hereinafter referred to as 100% modulus). The higher this value, the harder the resin. The polyurethane resin preferably has a 100% modulus of 1 to 10 MPa, more preferably 3 to 8 MPa, and even more preferably 4 to 7 MPa. When the 100% modulus is within the above range, it becomes easier to achieve both a high polishing rate and defect suppression.

[0025] <Cellulose derivatives> The resin sheet preferably contains a cellulose derivative. By containing the cellulose derivative, the difference in relaxation time ΔT 2s,15min This increases the polishing pad's start-up processability. 2s,120min , SD(T 2s,15-120min The dressing time required for the relaxation time of the amorphous phase component to reach 0.8 ms or more also tends to fall within the above range. Examples of cellulose derivatives include ester-based cellulose derivatives, ether-based cellulose derivatives, ether-ester-based cellulose derivatives, and aromatic-containing derivatives. Among these, ester-based cellulose derivatives are more preferred. Examples of ester-based cellulose derivatives include acetyl cellulose, triacetyl cellulose, acetyl butyl cellulose, diacetyl cellulose, acetyl propyl cellulose, ethyl cellulose, cellulose propionate, cellulose butyrate, nitrocellulose, cellulose sulfate, cellulose phosphate, cellulose acetate butyrate, cellulose acetate nitrate, and cellulose acetate propionate. Among these, acetyl cellulose, triacetyl cellulose, acetyl butyl cellulose, diacetyl cellulose, and acetyl propyl cellulose are preferred, and cellulose in which some or all of the OH groups have been converted to acetate esters, such as acetyl cellulose and triacetyl cellulose (particularly acetyl cellulose with a degree of substitution of 2.41), is more preferred.

[0026] <Hydrophilic surfactant> The resin sheet may contain a hydrophilic surfactant. When the resin sheet contains a hydrophilic surfactant, the hydrophilic surfactant is preferably contained in the resin sheet together with the cellulose derivative. By containing the hydrophilic surfactant together with the cellulose derivative, the difference in relaxation time ΔT 2s,15min becomes larger, and ΔT 2s,15min This makes it easier to adjust ΔT to the above numerical range, which makes it easier to improve the rising processability of the polishing pad. 2s,120min , SD(T 2s,15-120min The dressing time required for the relaxation time of the non-crystalline phase component to reach 0.8 ms or more also tends to fall within the above range. The reason for this is unclear, but is presumed to be as follows: By using a hydrophilic surfactant together with a cellulose derivative, the hydrophilic surfactant is less likely to escape into the coagulation bath during production, and most of it remains in the resin sheet. This allows the hydrophilic surfactant in the resulting resin sheet to trap more water molecules in the slurry, allowing the slurry to quickly adapt to the resin sheet. Until the slurry penetrates and adapts to the polishing pad, uneven adaption occurs, making the polishing rate unstable. It is presumed that the improved adaptability of the slurry to the resin sheet suppresses uneven adaption and shortens the time until the polishing pad's polishing rate stabilizes (improving start-up processability). Examples of hydrophilic surfactants include anionic surfactants and cationic surfactants. Among these, anionic surfactants are preferred. Among anionic surfactants, sulfonate-based surfactants are more preferred. Examples of sulfonate surfactants include sodium lauryl sulfate, sodium alkylbenzenesulfonate, and sodium sulfosuccinate alkyl esters. Among these, sodium sulfosuccinate alkyl esters are preferred. Examples of sodium sulfosuccinate alkyl esters that can be used include CRISBON ASISTER SD-11 (trade name, manufactured by DIC Corporation).

[0027] <Coagulation modifier and / or nonionic surfactant> The resin sheet may contain a solidification modifier and / or a nonionic surfactant. Examples of solidification modifiers include those composed only of carbon and hydrogen atoms (e.g., hydrocarbons having 8 to 18 carbon atoms), such as paraffinic modifiers, aromatic modifiers, naphthenic modifiers, mineral oils, and synthetic oils. Among these, paraffinic modifiers (e.g., isoalkane) and polybutene are preferred. For example, CRISBON ASISTOR SD-8i manufactured by DIC Corporation can be used. Examples of nonionic surfactants include polyalkylene glycol ethylene oxide, polyether-modified silicone oil, and copolymers of ethylene oxide and propylene oxide. Among these, copolymers of ethylene oxide and propylene oxide are preferred. As the copolymer of ethylene oxide and propylene oxide, for example, CRISBON ASISTER SD-21 (trade name, manufactured by DIC Corporation) can be used.

[0028] <Other surfactants> The resin sheet may contain a surfactant other than those described above, such as a carboxylic acid surfactant, a sulfate ester surfactant, a phosphate ester surfactant, an ester surfactant, or an alkanolamide surfactant.

[0029] <Polyol compounds> The resin sheet may contain a polyol compound. The polyol compound referred to here is a polyol compound that is added separately from the polyurethane resin during the preparation of the resin sheet and is contained in the resin sheet. Examples of polyol compounds include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2,3-propanetriol, 1,3-butanediol, 1,4-butanediol, and diethylene glycol. Among these, diethylene glycol is preferred. The amount of polyol contained in the resin sheet is not particularly limited, but is preferably more than 100 ppm, more preferably 105 ppm or more, more preferably 110 ppm or more, even more preferably 115 ppm or more, and even more preferably 120 ppm or more. There is no particular limit to the upper limit of the amount of polyol contained in the resin sheet, and it may be 1000 ppm or less, 800 ppm or less, 600 ppm or less, 400 ppm or less, 200 ppm or less, or 150 ppm or less. Furthermore, when the polyol compound is diethylene glycol, the amount of diethylene glycol contained in the resin sheet is preferably more than 100 ppm, preferably 105 ppm or more, more preferably 110 ppm or more, even more preferably 115 ppm or more, and even more preferably 120 ppm or more. There is no particular upper limit to the amount of diethylene glycol contained in the resin sheet, and it may be 1000 ppm or less, 800 ppm or less, 600 ppm or less, 400 ppm or less, 200 ppm or less, or 150 ppm or less. When the resin sheet contains a coagulation regulator and / or a nonionic surfactant, it is preferable that the resin sheet contains a polyol compound. The polyol compound is preferably contained in the resin sheet together with a cellulose derivative. By containing the polyol compound together with the above components, the difference in relaxation time ΔT of the amorphous phase component can be reduced. 2s,15min becomes larger, and ΔT 2s,15min This makes it easier to adjust ΔT to the above numerical range, which makes it easier to improve the rising processability of the polishing pad. 2s,120min , SD(T 2s,15-120min), or the dressing time required for the relaxation time of the amorphous phase component to reach 0.8 ms or more, also tends to fall within the above range. The reason for this is unclear, but is presumed to be as follows. Although coagulation modifiers and / or nonionic surfactants are less hydrophilic than hydrophilic surfactants and have poorer water molecule-trapping capabilities, the use of a polyol compound together with a cellulose derivative makes it difficult for the polyol compound to escape into the coagulation bath during production, and much of it is contained in the resin sheet. Therefore, even when using a coagulation modifier and / or nonionic surfactant, the polyol compound of the resin sheet can trap more water molecules in the slurry, and the slurry can be adapted to the resin sheet (the slurry penetrates into the resin sheet) in a short time, similar to when a hydrophilic surfactant is used. Until the slurry penetrates and adapts to the polishing pad, uneven adaptation occurs, making the polishing rate unstable. It is presumed that the slurry's improved adaptability to the resin sheet suppresses uneven adaptation and shortens the time until the polishing rate of the polishing pad stabilizes (improving start-up processability).

[0030] <Other ingredients> In the polishing pad of the present invention, the resin sheet may contain components other than those described above, such as fillers such as carbon black, within the scope of the present invention, without impairing the effects of the present invention.

[0031] (Thickness) There are no particular restrictions on the thickness of the resin sheet in the polishing pad of the present invention, but it can be used in the range of, for example, 0.60 to 1.20 mm, preferably 0.70 to 1.10 mm, and more preferably 0.80 to 1.00 mm. (Buffing) The resin sheet may also be buffed. The buffing is preferably performed on the skin layer side (polished surface side) of the film-forming resin so that the thickness is uniform. The amount of buffing on the skin layer side by buffing is preferably 50 to 200 μm, more preferably 80 to 200 μm, even more preferably 100 to 200 μm, and even more preferably 120 to 180 μm. Within this range, the thickness of the polyurethane resin sheet is uniform, and sufficient pores for retaining the slurry on the polished surface can be secured. Furthermore, the polished surface of the resin sheet may be grooved, embossed and / or perforated (punched), preferably embossed.

[0032] (other layers) The polishing pad of the present invention is designed on the premise that the surface (polishing surface) of the resin sheet will come into contact with the object to be polished, and therefore no other resin layer exists on the polishing surface of the resin sheet. On the other hand, in the polishing pad of the present invention, another resin layer (lower layer, support layer) may be attached to the surface of the resin sheet opposite to the surface (polishing surface) used to polish the object to be polished, or no other resin layer may be attached. The properties of the other resin layer are not particularly limited, but it is preferable that a layer harder than the resin sheet (high hardness such as Shore A hardness or Shore D hardness) is attached. By providing a layer harder than the resin sheet, it is possible to prevent minute irregularities on the polishing table from affecting the shape of the polishing surface, further improving polishing flatness. In addition, by increasing the rigidity of the polishing pad as a whole, it is possible to suppress the occurrence of wrinkles when attaching the polishing pad to the polishing table, thereby improving workability.

[0033] <<Polishing pad of second embodiment>> A second aspect of the polishing pad of the present invention is a polishing pad comprising a resin sheet having a plurality of teardrop-shaped bubbles and a polishing surface for polishing an object to be polished, wherein the resin sheet comprises a cellulose derivative and a hydrophilic surfactant, or the resin sheet comprises a cellulose derivative, a coagulation adjuster and / or a nonionic surfactant, and a polyol compound. The components of the polishing pad of the second embodiment can be the same as those described for the polishing pad of the first embodiment. Other aspects such as thickness and buffing can also be applied as appropriate to the polishing pad of the first embodiment. By having the above combination, the polishing pad of the present invention can easily obtain a polishing pad with excellent start-up processability. The reason for this is not entirely clear, but is presumed to be as follows. Generally, hydrophilic surfactants and polyol compounds have good compatibility with the slurry, but also with the coagulation liquid, so it is thought that a large amount of them will be dissolved from the resin-containing solution composition into the coagulation liquid during the coagulation process, and almost none will remain in the resin sheet after the coagulation process. In contrast, by using a cellulose derivative in combination with a hydrophilic surfactant and a polyol compound, the cellulose derivative promotes the formation of urethane resin crystal nuclei during the coagulation process, and the hydrophilic surfactant and polyol compound are incorporated into the crystal nuclei together with the resin before they are dissolved into the coagulation liquid, thereby increasing the amount of hydrophilic surfactant and polyol compound remaining in the resin sheet after the coagulation process. This is thought to increase the hydrophilicity of the polishing layer of the polishing pad, making it easier to mix with the slurry even at the beginning of polishing, thereby improving start-up performance. Furthermore, even when using a coagulation adjuster or a nonionic surfactant, by combining it with a highly hydrophilic polyol compound, and further by combining it with a cellulose derivative, it is possible to ensure a moderate hydrophilicity while preventing elution into the coagulation bath, which is thought to maintain a high hydrophilicity in the resin sheet after the coagulation process. This is thought to make it easier to blend with the slurry even in the early stages of polishing, improving the start-up. Furthermore, the polishing pad of the present invention, which has the above combination, is less likely to cause defects such as scratches on the surface of the workpiece to be polished, and can achieve a high polishing rate.

[0034] In addition, in the polishing pad of the second embodiment, when the free induction decay signal (FID) obtained by pulse NMR is subjected to waveform separation by subtracting the component with the longest spin-spin relaxation time T2 from the component with the longest spin-spin relaxation time T2 by the least squares method, and the result is divided into three components, namely, an amorphous phase, an interface phase, and a crystalline phase, in order of the longest spin-spin relaxation time T2, the relaxation time T of the amorphous phase component of the resin sheet obtained from the measurement result of the relaxation time using pulse NMR after dressing the resin sheet for 15 minutes is 2s,15min and the relaxation time T of the amorphous phase component of the resin sheet obtained from the measurement results of the relaxation time using pulse NMR in a dry state before dressing the polishing pad. 2s,dry The difference between 2s、15min It is preferable that ΔT is 0.35 ms or more. 2s、15min is more preferably 0.36 ms or more, even more preferably 0.38 ms or more, and even more preferably 0.40 ms or more. ΔT 2s、15min There is no particular limit to the upper limit, and it may be 0.60 ms or less, 0.55 ms or less, or 0.50 ms or less.

[0035] The polishing pad of the second embodiment is characterized in that the SD (T 2s,15-120min ) is preferably less than 0.05 ms. 2s,15-120min ) is more preferably 0.04 ms or less, even more preferably 0.030 ms or less, even more preferably 0.025 ms or less, even more preferably 0.018 ms or less, and even more preferably 0.015 ms or less.

[0036] The polishing pad of the second embodiment has a relaxation time T of the amorphous phase component obtained from the measurement of the relaxation time using pulse NMR after dressing the polishing pad for 2 hours. 2s,120minand the relaxation time T of the amorphous phase component obtained from the measurement results of the relaxation time using pulse NMR in a dry state before dressing the polishing pad. 2s,dry The difference between 2s,120min It is preferable that ΔT is 0.35 ms or more. 2s、120min is more preferably 0.36 ms or more, even more preferably 0.38 ms or more, and even more preferably 0.40 ms or more. ΔT 2s、120min There is no particular limit to the upper limit, and it may be 0.60 ms or less, 0.55 ms or less, or 0.50 ms or less.

[0037] (Application) The polishing pad of the present invention can be suitably used as a polishing pad for polishing (chemical mechanical polishing (CMP)) objects to be polished, such as semiconductor devices, semiconductor wafers, silicon, glass, etc. Among these, the polishing pad of the present invention can be suitably used as a polishing pad for semiconductor devices. The polishing pad of the present invention can be suitably used for chemical mechanical polishing of an object to be polished using a polishing slurry, and can also be suitably used for chemical mechanical polishing using a colloidal silica-containing slurry. The polishing pad of the present invention can be produced, for example, by the following method.

[0038] <<Polishing pad manufacturing method>> The manufacturing method of the polishing pad of the present invention can be manufactured by a conventionally known wet film-forming method.Preferably, the manufacturing method of the polishing pad comprises the steps of: coating a film-forming substrate with a resin solution composition comprising a polyurethane resin, a cellulose derivative, and a hydrophilic surfactant, or a polyurethane resin, a cellulose derivative, a coagulation adjuster and / or a nonionic surfactant, and a polyol compound; and immersing the film-forming substrate coated with the resin solution composition in a coagulation liquid to coagulate the resin solution composition, thereby forming a wet-film-formed resin sheet. Each step will be described below.

[0039] <Preparation process> In the preparation step, a resin solution composition containing a polyurethane resin, a cellulose derivative, and a hydrophilic surfactant is prepared, or a resin solution composition containing a polyurethane resin, a cellulose derivative, a coagulation adjuster and / or a nonionic surfactant, and a polyol compound is prepared.

[0040] (Polyurethane resin) The resin solution composition contains a polyurethane resin, which is a material for the polyurethane polishing sheet. As the polyurethane resin, the polyurethane resins mentioned in the description of the polishing pad can be used.

[0041] (cellulose derivatives) The resin solution composition preferably contains a cellulose derivative. As the cellulose derivative, the cellulose derivatives mentioned in the description of the polishing pad can be used. The cellulose derivative is preferably contained in the resin solution composition in an amount of 0.1 to 35 parts by mass, more preferably 0.3 to 30 parts by mass, even more preferably 1 to 20 parts by mass, even more preferably 2 to 10 parts by mass, even more preferably 3 to 9 parts by mass, and even more preferably 4 to 8 parts by mass, relative to 100 parts by mass of the polyurethane resin.

[0042] (hydrophilic surfactant) The resin solution composition may contain a hydrophilic surfactant. The hydrophilic surfactants mentioned in the description of the polishing pad can be used as the hydrophilic surfactant. The hydrophilic surfactant is preferably contained in the resin solution composition in an amount of 0.1 to 35 parts by mass, more preferably 0.3 to 30 parts by mass, even more preferably 1 to 20 parts by mass, even more preferably 2 to 10 parts by mass, even more preferably 3 to 9 parts by mass, and even more preferably 4 to 8 parts by mass, per 100 parts by mass of the polyurethane resin.

[0043] (coagulation regulator) The resin solution composition may contain a solidification regulator. The solidification regulators mentioned in the description of the polishing pad can be used as the solidification regulator. The solidification regulator is preferably contained in the resin solution composition in an amount of 0.1 to 35 parts by mass, more preferably 0.3 to 30 parts by mass, even more preferably 1 to 20 parts by mass, even more preferably 5 to 20 parts by mass, even more preferably 8 to 18 parts by mass, and even more preferably 10 to 16 parts by mass, per 100 parts by mass of the polyurethane resin.

[0044] (nonionic surfactants) The resin solution composition may contain a nonionic surfactant. The nonionic surfactants mentioned in the description of the polishing pad can be used as the nonionic surfactant. The resin solution composition preferably contains 0.1 to 35 parts by mass of the nonionic surfactant, more preferably 0.3 to 30 parts by mass, even more preferably 1 to 20 parts by mass, even more preferably 2 to 10 parts by mass, even more preferably 3 to 9 parts by mass, and even more preferably 4 to 8 parts by mass, per 100 parts by mass of the polyurethane resin. Furthermore, the total amount of the coagulation adjuster and nonionic surfactant contained in the resin solution composition is preferably 0.1 to 50 parts by mass, more preferably 0.3 to 40 parts by mass, even more preferably 1 to 30 parts by mass, even more preferably 5 to 30 parts by mass, even more preferably 8 to 25 parts by mass, even more preferably 10 to 25 parts by mass, and even more preferably 12 to 24 parts by mass, per 100 parts by mass of the polyurethane resin.

[0045] (Polyol compound) The resin solution composition may contain a polyol compound. The polyol compounds mentioned in the description of the polishing pad can be used as the polyol compound. The polyol compound is preferably contained in the resin solution composition in an amount of 0.1 to 35 parts by mass, more preferably 0.3 to 30 parts by mass, even more preferably 1 to 25 parts by mass, even more preferably 5 to 20 parts by mass, even more preferably 10 to 20 parts by mass, and even more preferably 12 to 18 parts by mass, relative to 100 parts by mass of the polyurethane resin.

[0046] (organic solvent) The organic solvent can be any solvent that can dissolve the polyurethane resin and is miscible with water. Examples include N,N-dimethylformamide (DMF), methyl ethyl ketone, N,N-dimethylacetamide (DMAc), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), and acetone. Among these, DMF and DMAc are preferably used. The organic solvent is preferably contained in the resin solution composition in an amount such that the solids concentration in the resin solution composition is preferably 10 to 50 mass %, more preferably 10 to 40 mass %, and even more preferably 20 to 40 mass %. If the concentration is within the above range, the resin solution composition has appropriate fluidity and can be uniformly applied onto a film-forming substrate in the subsequent application step.

[0047] (micropore adjuster / density adjuster) In addition to the above components, the resin solution composition may contain a micropore adjusting agent or a density adjusting agent, such as water. The micropore adjuster / density adjuster is preferably contained in an amount of 0.1 to 35 parts by mass, more preferably 0.3 to 30 parts by mass, even more preferably 1 to 25 parts by mass, even more preferably 5 to 20 parts by mass, even more preferably 10 to 20 parts by mass, and even more preferably 12 to 18 parts by mass, relative to 100 parts by mass of the polyurethane resin.

[0048] (Other ingredients) The resin solution composition may further contain other components in addition to the above components, as long as the effects of the present invention are not impaired. As the other components, the other components listed in the description of the polishing pad can be used. The resin solution composition preferably does not contain a fluorine-based water repellent having a polyfluoroalkyl group, preferably does not contain a fluorine-based water repellent, more preferably does not contain a fluorine-based water repellent, a silicone-based water repellent, or a hydrocarbon-based water repellent, and preferably does not contain a water repellent.

[0049] <Coating process> The resin solution composition obtained above is continuously applied to the film-forming substrate at room temperature so as to be substantially uniform, for example, by a knife coater, a reverse coater, etc. At this time, the coating thickness (coating amount) of the resin solution composition can be adjusted by adjusting the gap (clearance) between the knife coater and the film-forming substrate. The film-forming substrate can be any substrate commonly used in this technical field without any particular limitations. Examples of the film-forming substrate include flexible films, nonwoven fabrics, woven fabrics, etc. Flexible films include flexible polymer films such as polyester films and polyolefin films. Nonwoven fabrics and woven fabrics include nonwoven fabrics and woven fabrics impregnated with elastic resins. When using nonwoven fabrics or woven fabrics as the film-forming substrate, it is preferable to perform a pretreatment (sealing) by immersing the substrate in water or an aqueous organic solvent solution (such as a mixture of DMF and water) in advance to prevent the resin solution composition from penetrating into the film-forming substrate during application of the resin solution composition. Among these, polyester films are preferably used.

[0050] <Coagulation process> The film-forming substrate coated with the resin solution composition is immersed in a coagulation liquid mainly composed of water, which is a poor solvent for polyurethane resin, to coagulate the resin solution composition, thereby forming a wet-coated resin sheet. The coagulation liquid may be water or a mixed solution of water and a polar solvent such as DMF. Examples of the polar solvent include the water-miscible organic solvents used to dissolve the polyurethane resin, such as DMF, DMAc, THF, DMSO, NMP, and acetone. The concentration of the polar solvent in the mixed solvent is preferably 0.5 to 30% by mass. There are no particular limitations on the temperature of the coagulation liquid or the immersion time, and immersion at 5 to 80° C. for 5 to 60 minutes may be sufficient, for example. In the solidification process, the coating film obtained in the coating process (the film-forming substrate coated with the resin solution composition) is immersed in a solidification liquid (e.g., water or a water-based solvent) that is a poor solvent for the polyurethane resin, and the coated film of the resin solution composition is solidified and regenerated into a sheet with numerous bubbles inside. In the solidification liquid, a skin layer with a thickness of several micrometers and formed with micropores is generally first formed on the surface of the applied resin solution composition. Subsequently, as the organic solvent in the resin solution composition is replaced with the solidification liquid, the polyurethane resin is solidified and regenerated into a sheet on one side of the film-forming substrate. Typically, the organic solvent is removed from the resin solution composition, and the organic solvent is replaced with the solidification liquid. As a result, bubbles with a rounded, approximately triangular cross section (teardrop-shaped bubbles) are formed on the underside (film-forming substrate side) of the skin layer, which are larger in pore size than the micropores formed in the skin layer and are distributed approximately evenly across the thickness of the sheet. However, the foam structure is not limited to this. The sheet thus obtained typically contains a plurality of interconnected cells, including teardrop-shaped cells and a plurality of substantially spherical microbubbles smaller than the teardrop-shaped cells, which are interconnected with each other.

[0051] <Washing and drying> After the coagulation step, the resin sheet obtained by wet film formation through coagulation in the coagulation bath may be washed and dried after or without being peeled off from the film-forming substrate. The washing treatment removes the organic solvent remaining in the resin sheet formed by the wet process. An example of the washing liquid used for washing is water. After washing, the wet-formed resin sheet may be dried. The drying may be performed by a conventional method, for example, by drying in a dryer at 80 to 150°C for about 5 to 60 minutes. A resin sheet can be obtained through the above steps.

[0052] In the method for producing a polishing pad of the present invention, the polishing surface and / or the surface opposite to the polishing surface of the resin sheet may be ground (buffed) as necessary. The polishing surface of the resin sheet may be grooved, embossed, and / or perforated (punched), or a substrate may be bonded to the resin sheet. Furthermore, a light-transmitting portion may be provided on the resin sheet and / or the polishing pad. There are no particular limitations on the grinding method, and grinding can be performed by a known method, specifically, grinding with sandpaper. There are no particular limitations on the shape of the grooves and embossing, and examples thereof include lattice, concentric circle, and radial shapes. When substrates are bonded together to form a multilayer structure, the layers may be bonded and fixed together using double-sided tape, adhesive, etc., while applying pressure as necessary. There are no particular restrictions on the double-sided tape or adhesive used in this case, and any double-sided tape or adhesive known in the art may be selected and used.

[0053] Thereafter, double-sided tape is applied to the surface of the resin sheet opposite the polishing surface or the surface of the substrate opposite the surface bonded to the resin sheet, and the resulting sheet is cut into a predetermined shape, preferably a disk, to complete the polishing pad of the present invention. There are no particular restrictions on the double-sided tape, and any double-sided tape known in the art can be selected and used.

[0054] <Polishing method> The polishing method of the present invention is a method for polishing an object to be polished, which comprises a step of polishing the object to be polished with a polishing pad. During polishing, the object to be polished may be polished with the polishing pad while being held by a holding pad. When using the polishing pad of the present invention, the polishing pad is attached to the polishing table of a polishing machine so that the polishing surface of the resin sheet faces the object to be polished.Then, while supplying abrasive slurry, the polishing table is rotated to polish the processed surface of the object to be polished.As the polishing machine, either a single-sided polishing machine or a double-sided polishing machine can be used, but below, as a specific example, the polishing process when using a single-sided polishing machine will be described. First, the workpiece is held on the holding platen of the single-sided polishing machine. Next, a polishing pad is attached to the polishing platen positioned opposite the holding platen. Then, a slurry containing abrasive grains (abrasive particles) (polishing slurry) is supplied between the workpiece and the polishing pad, and the polishing platen or holding platen is rotated while pressing the workpiece against the polishing pad at a predetermined polishing pressure, thereby polishing the workpiece by chemical mechanical polishing. Examples of the object to be polished (held object) include semiconductor devices, semiconductor wafers, silicon, glass, etc. Among these, semiconductor devices are preferred as the object to be polished. Materials for semiconductor devices include silicon, polysilicon, silicon oxide film, silicon nitride, and metals such as Cu, W, Al, Ta, and TiN. As a method for polishing an object to be polished, for example, a method of polishing the surface of the object to be polished using a polishing liquid (polishing slurry) can be mentioned. Examples of polishing slurries include slurries for barrier metals, slurries for oxide films, slurries for Cu, etc. The slurries may contain abrasive grains, oxidizing agents, components for protecting the object to be polished, etching agents, chelating agents, etc. Examples of the abrasive (abrasive grains) of the polishing slurry include silica (SiO2), alumina (Al2O3), ceria (CeO2), etc. Among these, silica is preferred, and colloidal silica is more preferred. The polishing slurry may be acidic, neutral, or alkaline, but is preferably acidic or alkaline in order to prevent the aggregation of abrasive grains and to facilitate the dispersion of abrasive grains. Among these, alkaline slurry is preferred. The polishing slurry may be adjusted by adding, to the above-mentioned slurry as needed, acidic components such as sulfuric acid or phosphoric acid, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, organic alkali compounds such as tetramethylammonium hydroxide and choline, and alkaline components such as ammonia. [Example]

[0055] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In each example and comparative example, unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass".

[0056] Example 1 A resin-containing solution was prepared by adding 40 parts by weight of DMF, 2 parts by weight of an anionic surfactant consisting of sodium sulfosuccinate alkyl ester (product name: CRISBON ASISTOR SD-11, manufactured by DIC Corporation), 2 parts by weight of acetyl cellulose (product name: L-20, manufactured by Daicel Corporation), and 5 parts by weight of water to 100 parts by weight of an ester-based polyurethane resin solution (solids concentration: 30% by weight) with a 100% modulus of 5.9 MPa. The polyester-based polyurethane resin used was obtained by condensing a polyester polyol (used without distillation, low molecular weight diol content: 12.9 mol%) obtained by dehydration condensation of 1,4-butanediol and adipic acid with a chain extender of 1,4-butanediol / trimethylolpropane in a molar ratio of 60 / 40 and 4,4'-diphenylmethane diisocyanate (MDI). Next, a PET film was prepared as a substrate for film formation. The resin solution was applied to the film using a knife coater, and the film was immersed in a coagulation bath of water to coagulate the resin-containing solution. The film was then washed and dried to obtain a resin film. The skin layer formed on the surface of the resulting resin film was subjected to a 100 μm buffing treatment to obtain a 0.80 mm thick polyurethane sheet. A PET substrate was then attached to the backside of the buffed surface via double-sided tape, and the buffed surface was embossed with a grid-shaped mold. Double-sided tape with release paper was attached to the unembossed surface to secure it to a polishing platen, obtaining a polishing pad.

[0057] <Example 2> A resin-containing solution was prepared by adding 40 parts by weight of DMF, 2 parts by weight of an anionic surfactant consisting of sodium sulfosuccinate alkyl ester (product name: CRISBON ASISTOR SD-11, manufactured by DIC Corporation), and 2 parts by weight of acetyl cellulose (product name: L-20, manufactured by Daicel Corporation) to 100 parts by weight of an ester-based polyurethane resin solution (solids concentration: 30% by weight) with a 100% modulus of 5.9 MPa. The polyester-based polyurethane resin used was obtained by condensing a polyester polyol (used without distillation, low molecular weight diol content: 12.9 mol%) obtained by dehydration condensation of 1,4-butanediol and adipic acid with a chain extender of 1,4-butanediol / trimethylolpropane in a molar ratio of 60 / 40 and 4,4'-diphenylmethane diisocyanate (MDI). Next, a PET film was prepared as a substrate for film formation. The resin solution was applied to the film using a knife coater, and the film was immersed in a coagulation bath of water to coagulate the resin-containing solution. The film was then washed and dried to obtain a resin film. The skin layer formed on the surface of the resulting resin film was buffed to a depth of 150 μm to obtain a 0.95 mm thick polyurethane sheet. A PET substrate was then attached to the backside of the buffed surface via double-sided tape. The buffed surface was embossed with a grid-shaped mold, and double-sided tape with release paper was attached to the unembossed surface to secure it to a polishing platen, obtaining a polishing pad.

[0058] Example 3 A resin-containing solution was obtained by adding 31.8 parts by mass of DMF, 4 parts by mass of a coagulation adjuster consisting of paraffin (trade name: CRISBON ASISTER SD-8i, manufactured by DIC Corporation), 2 parts by mass of a nonionic surfactant consisting of a copolymer of ethylene oxide and propylene oxide (trade name: CRISBON ASISTER SD-21, manufactured by DIC Corporation), 2 parts by mass of acetylcellulose (trade name: L-20, manufactured by Daicel Corporation), 5 parts by mass of diethylene glycol, and 5 parts by mass of pure water to 100 parts by mass of an ester-based polyurethane resin solution (solids concentration 30% by mass) with a 100% modulus of 5.9 MPa. The polyester-based polyurethane resin used was a polyester polyol (used without distillation, low-molecular-weight diol component 12.9 mol%) obtained by dehydration condensation of 1,4-butanediol and adipic acid, a chain extender of 1,4-butanediol / trimethylolpropane = 60 / 40 molar ratio, and condensation with 4,4'-diphenylmethane diisocyanate (MDI). Next, a PET film was prepared as a film-forming substrate, and the above resin solution was applied to it using a knife coater. The film was then immersed in a coagulation bath of water to coagulate the resin-containing solution, followed by washing and drying to obtain a resin film. The skin layer formed on the surface of the obtained resin film was subjected to 150 μm buffing to obtain a polyurethane sheet with a thickness of 0.80 mm. A PET substrate was then attached to the backside of the buffed surface via double-sided tape, the buffed surface was embossed using a grid-shaped mold, and double-sided tape with release paper was attached to the unembossed surface to fix it to the polishing platen, thereby obtaining a polishing pad.

[0059] <Comparative Example 1> A resin-containing solution was obtained by adding 31.8 parts by mass of DMF and 5 parts by mass of water to 100 parts by mass of an ester-based polyurethane resin solution (solids concentration 30% by mass) with a 100% modulus of 5.9 MPa. The polyester-based polyurethane resin used was a polyester polyol (used without distillation, low molecular weight diol content 12.9 mol%) obtained by dehydration condensation of 1,4-butanediol and adipic acid, a chain extender in a 60 / 40 molar ratio of 1,4-butanediol / trimethylolpropane, and 4,4'-diphenylmethane diisocyanate (MDI). Next, a PET film was prepared as a film-forming substrate. The resin solution was applied to the film using a knife coater, immersed in a coagulation bath of water, and the resin-containing solution was coagulated. The resin film was then washed and dried to obtain a resin film. The skin layer formed on the surface of the resulting resin film was subjected to a 150 μm buffing process to obtain a 0.80 mm-thick polyurethane sheet. A PET substrate was then attached to the backside of the buffed surface via double-sided tape, the buffed surface was embossed using a grid-shaped mold, and double-sided tape with release paper was attached to the unembossed surface to fix it to the polishing platen, thereby obtaining a polishing pad.

[0060] <Comparative Example 2> A resin-containing solution was obtained by adding 31.8 parts by mass of DMF, 2 parts by mass of a coagulation adjuster consisting of paraffin (trade name: CRISBON ASISTER SD-8i, manufactured by DIC Corporation), 2 parts by mass of a nonionic surfactant consisting of a copolymer of ethylene oxide and propylene oxide (trade name: CRISBON ASISTER SD-21, manufactured by DIC Corporation), 2 parts by mass of acetylcellulose (trade name: L-20, manufactured by Daicel Corporation), and 5 parts by mass of pure water to 100 parts by mass of an ester-based polyurethane resin solution (solids concentration: 30% by mass) with a 100% modulus of 5.9 MPa. The polyester-based polyurethane resin used was a polyester polyol (used without distillation, low-molecular-weight diol component 12.9 mol%) obtained by dehydration condensation of 1,4-butanediol and adipic acid, a chain extender of 1,4-butanediol / trimethylolpropane = 60 / 40 molar ratio, and condensation with 4,4'-diphenylmethane diisocyanate (MDI). Next, a PET film was prepared as a film-forming substrate, and the above resin solution was applied to it using a knife coater. The film was then immersed in a coagulation bath of water to coagulate the resin-containing solution, followed by washing and drying to obtain a resin film. The skin layer formed on the surface of the obtained resin film was subjected to 150 μm buffing to obtain a polyurethane sheet with a thickness of 0.80 mm. A PET substrate was then attached to the backside of the buffed surface via double-sided tape, the buffed surface was embossed using a grid-shaped mold, and double-sided tape with release paper was attached to the unembossed surface to fix it to the polishing platen, thereby obtaining a polishing pad.

[0061] <1. Pulsed NMR analysis> The relaxation times and proportions of the crystalline phase, interface phase, and amorphous phase in the polyurethane sheet were measured using pulsed NMR as follows. First, four pieces of polishing pads were cut into approximately 20 x 10 mm squares. After peeling off the release paper from the backside, the two pieces were glued together to prepare two plate-shaped samples with double polishing surfaces. A 1 cm diameter glass tube containing two plate-shaped samples was placed in a magnetic field. A high-frequency pulsed magnetic field was applied, and the relaxation behavior of the macroscopic magnetization was measured. Free induction decay (FID) signals were obtained, as shown in Figure 2 (horizontal axis: time (msec); vertical axis: free induction decay signal). The initial value of the FID signal obtained is proportional to the number of protons in the sample. If the sample contains three components, the FID signal appears as the sum of the response signals of the three components. However, because the components in the sample have different mobilities, the decay rates of the response signals differ between the components, resulting in different spin-spin relaxation times, T2. Therefore, the sample can be separated into three components using the least-squares method. The phases with the longest spin-spin relaxation times, T2, are the amorphous phase, the interface phase, and the crystalline phase, respectively (see Figure 2). The amorphous phase is a component with large molecular mobility, the crystalline phase is a component with small molecular mobility, and the component in between is the interface phase. After the FID signal is obtained, fitting is performed to separate the FID signal into signals for three components with different kinetics (crystalline phase component, interface phase component, and amorphous phase component). Fitting is performed using BRUKER's analysis software "TD-NMR Analyzer," and the obtained relaxation curve is fitted using the following calculation formula 1 according to the product manual. The ratio and relaxation time of each component are determined from the curve derived from the three components obtained by measurement. The fitting is performed in two stages. First, in the first stage, the FID signal in the measurement time range of 0.15-2.0 ms is fitted to a single component (i.e., the amorphous phase component only), and the FID signal of the single component (amorphous phase component) in the 0-2.0 ms range is calculated (the FID signal of the single component (amorphous phase component) in the 0-0.15 ms range is also determined by fitting). Next, in the second step, the waveform obtained in the first fitting step is subtracted from the FID signal of all three components in the measurement time interval of 0-2.0 ms, and the waveform after subtraction is fitted as two components (i.e., the crystalline phase and the interface phase, which are the two components excluding the amorphous phase component from the three components of the crystalline phase, interface phase, and amorphous phase). This allows the FID signals of the crystalline phase and the interface phase to be separated from each other. In this embodiment, fitting is performed with the Weibull coefficients W(1)=2.0, W(2)=1.0, and W(3)=1.0 in ascending order of relaxation time T2. In the first step, the FID signal in the measurement time range of 0.15-2.0 ms was fitted using only the amorphous phase component because the amorphous phase component has a longer relaxation time than the crystalline phase component and the interface phase component (see Figure 2), and the FID signal with a measurement time of 0.15 ms or longer is thought to be derived from the amorphous phase component. In the second step, the FID signals of only the crystalline phase and interface phase are obtained by subtracting the waveform obtained in the first step. Therefore, by fitting using these two components, the waveforms of the crystalline phase component and the interface phase component can be determined more accurately. This analysis method is an analysis method that can obtain the characteristics of amorphous phase components with long relaxation times more clearly by dividing the number of components used in fitting and the analysis interval.

[0062] formula 1 TIFF2025156108000003.tif1773where I(t) is the fitting intensity at time t, a _i (n) represents the intensity factor of the nth component, T2(n) represents the relaxation time of the nth component, and W(n) represents the Weibull coefficient of the nth component.

[0063] (Sample preparation) Dry sample: The polishing pads of Examples 1 to 3 and Comparative Examples 1 and 2 were cut into approximately 20 × 10 mm squares, the release paper was peeled off, and the adhesive surfaces were bonded together to prepare plate-shaped samples. Two of the prepared plate-shaped samples (four 20 × 10 mm square polishing pads) were placed in a 10 mmφ pulse NMR measurement sample tube to prepare pulse NMR measurement samples. Dress sample: The 300 mm diameter polishing pads of Examples 1-3 and Comparative Examples 1-2 were placed on the surface plate of a single-sided polisher FAM 12BS (manufactured by SpeedFam Co., Ltd.), and then dressed using colloidal silica slurry and a 100 mm diameter diamond dresser (manufactured by 3M, model number A188) under the following dressing conditions. Dressing was performed for 5, 15, 30, 60, 90, and 120 minutes, respectively. The dressed polishing pads were cut into approximately 20 x 10 mm squares and bonded together to prepare plate-like samples. Two of the prepared plate-like samples (four 20 x 10 mm square polishing pads) were placed in a 10 mm diameter pulsed NMR measurement sample tube to prepare pulsed NMR measurement samples.

[0064] (Dress conditions) Polishing machine used: Speedfam, product name "FAM-12BS" Platen rotation speed (polishing pad rotation speed): 30 rpm Slurry: Colloidal silica slurry (pH: 11.5, a mixture of colloidal silica stock solution (silica concentration 14-16 wt%) and water = 1:3 (mass ratio) was used) Flow rate: 80 mL / min (The slurry was dropped from the center of rotation of the polishing pad.) Dresser: 3M diamond dresser, model number "A188" Dresser rotation speed: 30 rpm Dressing pressure: 10N Test duration: 5, 15, 30, 60, 90, 120 minutes

[0065] (Relaxation time of amorphous phase component) Pulsed NMR measurements were performed on samples (dressed samples) that had been dressed for 5, 15, 30, 60, 90, and 120 minutes in a dressing test, and on samples (dry samples) that had not been dressed. Analysis was performed using the method described in "Pulse NMR Analysis" above. The relaxation times of the amorphous phase components of the samples after 5-minute dressing, 15-minute dressing, 30-minute dressing, 60-minute dressing, 90-minute dressing, and 120-minute dressing, and the sample (dry sample) that had not been dressed, were measured as T 2s,5min , T 2s,15min , T2s,30min , T 2s,60min , T 2s,90min , T 2s,120min , T 2s,dry These relaxation times were determined for each of Examples 1 to 3 and Comparative Examples 1 and 2. The results are shown in Table 1 and FIG.

[0066] [Table 1]

[0067] (Amorphous phase component ratio (%)) The proportion of amorphous phase components in the polishing pads at each dressing time was determined based on the method described above in "Pulse NMR Analysis" for the polishing pads of Examples 1 to 3 and Comparative Examples 1 and 2. The results are shown in Table 2 and FIG.

[0068] [Table 2]

[0069] (ΔT2s,15, ΔT2s,120, SD(T2s,15-120min)) Using the results of the relaxation times obtained for the polishing pads of Examples 1 to 3 and Comparative Examples 1 and 2, ΔT was calculated using the following formula: 2s,15min , ΔT 2s,120min , SD(T 2s,15-120min The results are shown in Table 3. TIFF2025156108000006.tif45151 ΔT 2s,15min The difference between the relaxation time T2s, 15 min of the amorphous phase components in a specimen dressed for 15 minutes and the relaxation time T2s, dry of the amorphous phase components in a specimen not subjected to a dressing test ΔT 2s,120min The difference between the relaxation time T2s, 120 min of the amorphous phase components in the specimen dressed for 120 min and the relaxation time T2s, dry of the amorphous phase components in the specimen not subjected to the dressing test SD(T 2s,15-120min ): Variation in the five relaxation time T2s values ​​obtained from the relaxation time T2s of the amorphous phase components in samples dressed for 15, 30, 60, 90, and 120 minutes

[0070] [Table 3]

[0071] (amount of diethylene glycol) In order to confirm that hydrophilic surfactants and polyol compounds are likely to remain in the resin sheet in the polishing pads of the present invention, the amount of diethylene glycol contained in the resin film after film formation in Example 3 and Comparative Example 1 was measured using the following method. Approximately 270 mg of the resin film after film formation in Example 3 and Comparative Example 1 was sampled and weighed. The sampled resin was then transferred to a vial and extracted with ethanol (3 mL of ethanol, left to stand on a hot plate at 70°C for 6 hours for extraction). The above procedure from collection to extraction was repeated three times, and a total of approximately 9 mL of extract was obtained. Ethanol was added to the extracted solution to make a total volume of 10 mL. The extracted solution after adding ethanol was diluted with acetone (HPLC-grade acetone to which a small amount of tetradecane (an amount that approximates the peak size of the target compound to some extent)) (extract:acetone = 2:1 (volume ratio)) to obtain a measurement sample. The measurement sample prepared as described above was measured by gas chromatography mass spectrometry to quantify (mg) the amount of diethylene glycol (DEG). The results are shown in Figures 10 and 11.

[0072] The measurement conditions for gas chromatography mass spectrometry are as follows: [Device] Gas chromatograph mass spectrometer: GC / MS-QP2020 NX (Shimadzu Corporation) Sample injector: AOC-20i Plus (Shimadzu Corporation) [Gas chromatographic conditions] Carrier gas: Helium Column: DB-WAXetr (inner diameter 0.25 mm, length 30 m, film thickness 0.25 μm) Linear speed: 36.1cm / sec Sample injection volume: 1 μL Gas chromatograph inlet temperature: 250°C Split ratio = 1:20 Column bath temperature program: Temperature rise conditions are as shown in Table 4. [Mass spectrometry conditions] Ionization method: electron ionization method Mass spectrometer interface temperature: 220°C Scan range: m / z 29-350 Detection start time: 5 minutes after sample introduction

[0073] [Table 4] In the table, "-" indicates that no specific heating rate was set.

[0074] The DEG concentration in the resin was calculated by dividing the weight (mg) of the quantified DEG by the total weight (g) of the collected resin. The results are shown in Table 5. As shown in Table 5, a sufficient amount of DEG was contained in the resin sheet of Example 3. A very small amount of DEG was also detected in Comparative Example 1, but this is thought to be due to DEG contained in the raw materials.

[0075] [Table 5]

[0076] <2. Polishing test> Using the polishing pads of each Example and Comparative Example, polishing was performed on 120 silicon wafers with a TEOS (tetraethoxysilane) film and 120 silicon wafers with a Cu film under the following conditions, and the polishing rate and defect performance were evaluated.

[0077] (polishing conditions) Polishing machine used: Ebara Corporation, product name "F-REX300" Polishing speed (platen rotation speed): 70 rpm Processing pressure: 176g / cm 2 Slurry flow rate: 200 mL / min Dresser: 3M diamond dresser, model number "A189L" Conditioning: Ex-situ, 30N, 4 scans Polishing time: 60 seconds Polished object: TEOS-coated silicon wafer and Cu-coated silicon wafer Polishing slurry: Colloidal silica slurry (pH: 11.5, a mixture of colloidal silica stock solution (silica concentration 14-16 wt%):water = 1:3 (mass ratio) was used) The polishing pad was placed on the polishing platen of the polishing machine, and before the polishing test, the dresser and polishing pad were rotated using the slurry and the dresser at a dressing pressure of 30 N, a dresser rotation speed of 70 rpm, and a polishing pad rotation speed of 70 rpm, and the polishing pad was dressed for 30 minutes while dropping the slurry onto the center of rotation of the polishing pad at a rate of 200 mL per minute. Then, the following polishing test was performed.

[0078] (polishing rate) The polishing rate (Å / min) was calculated by dividing the thickness measured at each point by the polishing time. The thickness was measured using an optical film thickness and film quality analyzer (KLA-Tencor Corporation, model number "ASET-F5x" in DBS mode). The results are shown in Table 6 and Figures 5 to 8. The leftward arrows in Figures 6 to 8 indicate that the number of wafers required to stabilize the polishing rate was reduced from 300 wafers in Comparative Example 1 and 150 wafers in Comparative Example 2 to 50 wafers in Examples 1 and 2 (Figure 7) and 10 wafers in Example 3 (Figure 8).

[0079] [Table 6]

[0080] From the obtained polishing rate results, the number of wafers required until the polishing rate stabilized (number of wafers in the initial process) was calculated and evaluated according to the following criteria. A+ and A were considered acceptable. The results are shown in Table 7. Evaluation criteria: A+: The number of sheets processed at startup is 25 or less, A: The number of sheets processed at startup is between 25 and 75 sheets. B: The number of sheets processed at startup is between 75 and 150 sheets. C: The number of sheets processed at startup is between 150 and 250 sheets. D: The number of sheets processed at startup is over 250.

[0081] [Table 7]

[0082] (Defect performance evaluation) For the Cu-coated silicon wafers after the polishing test described above, the 2nd, 4th, 6th, 8th, 12th, 27th, 52nd, and 77th polished wafers were examined using the high-sensitivity measurement mode of a surface inspection device (KLA-Tencor Corporation, Surfscan SP5) to detect and count defects (surface defects such as scratches) measuring 110 nm or larger. The results are shown in Table 8 and Figure 9. Furthermore, defect performance was evaluated according to the following criteria, with A+ and A being considered pass. The results are shown in Table 8. A+: The average number of defects on the surface of the 2nd, 4th, 6th, 8th, 12th, 27th, 52nd, and 77th silicon wafers processed is within 20. A: The average number of defects on the surface of the 2nd, 4th, 6th, 8th, 12th, 27th, 52nd, and 77th silicon wafers processed is between 20 and 40. B: The average number of defects on the surface of the processed silicon wafers (2nd, 4th, 6th, 8th, 12th, 27th, 52nd, and 77th) is more than 40.

[0083] [Table 8]

[0084] As a result of the polishing test, the polishing rate of the polishing pads of Comparative Examples 1 and 2 continued to increase from the beginning of polishing until the polishing of 300 or 150 wafers was completed, and it took a long time for the polishing rate to stabilize (poor start-up processability). Furthermore, the polishing pad of Comparative Example 1 had many defects at the time of start-up. In contrast, the polishing pads of Examples 1 to 3 stabilized their polishing rate after polishing about 50 wafers, and the time until the polishing rate stabilized was significantly shorter than that of Comparative Examples 1 and 2 (FIGS. 7 and 8), demonstrating excellent start-up processability. Furthermore, the polishing pads of Examples 1 to 3 also had few defects, demonstrating excellent start-up performance and defect reduction performance. Furthermore, it was also found that the polishing pads of Examples 1 to 3 had sufficiently high polishing rates and excellent polishing performance. [Industrial Applicability]

[0085] According to the present invention, a polishing pad with excellent build-up properties can be obtained, and therefore the polishing pad of the present invention is extremely useful industrially.

Claims

1. A polishing pad including a resin sheet having a plurality of teardrop-shaped bubbles and having a polishing surface for polishing an object to be polished, The free induction decay signal (FID) obtained by pulsed NMR was fitted to the spin-spin relaxation time T 2s By subtracting the longest component and separating the waveform, the spin-spin relaxation time T 2s When the resin sheet is divided into three components, namely, an amorphous phase, an interface phase, and a crystalline phase, in order from the longest, the relaxation time T of the amorphous phase component of the resin sheet obtained from the measurement result of the relaxation time using pulse NMR after dressing the polishing pad for 15 minutes is 2s,15min and the relaxation time T of the amorphous phase component of the resin sheet obtained from the measurement results of the relaxation time using pulse NMR in a dry state before dressing the polishing pad. 2s,dry The difference between 2s、15min is 0.35 ms or more.

2. 2. The polishing pad according to claim 1, wherein the resin sheet is a polyurethane sheet.

3. The relaxation time T of the amorphous phase component obtained from the measurement results of relaxation time using pulse NMR when the polishing pad was dressed for five times: 15 minutes, 30 minutes, 60 minutes, 90 minutes, and 120 minutes. 2s The standard deviation (S.D.) is the variation in the value of 2s,15-120min 3. The polishing pad according to claim 1, wherein the time t is less than 0.05 ms.

4. The relaxation time T of the amorphous phase component obtained from the measurement result of the relaxation time using pulse NMR after dressing the polishing pad for 2 hours 2s,120min and the relaxation time T of the amorphous phase component obtained from the measurement result of the relaxation time using pulse NMR in a dry state before dressing the polishing pad. 2s,dry The difference between 2s,120min The polishing pad according to claim 1 or 2, wherein the polishing time is 0.35 ms or more.

5. 3. The polishing pad according to claim 1, wherein the dressing time required for the relaxation time of the non-crystalline phase component obtained from the relaxation time measurement results using pulse NMR to become 0.8 ms or more when the polishing pad is dressed is within 15 minutes.

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