Polishing pad and method for manufacturing same

Abstract

The objective of the present invention is to provide a polishing pad having excellent startup properties, and a method for manufacturing the same. The polishing pad includes a resin sheet having a plurality of teardrop-shaped bubbles and having a polishing surface for polishing an object to be polished, wherein, if a free induction decay signal (FID) obtained by means of pulsed NMR is subjected to waveform separation by using the least squares method to sequentially subtract components having the longer spin-spin relaxation time T2s from the free induction decay signal (FID), to thereby divide the free induction decay signal (FID) into three components, namely an amorphous phase, an interface phase and a crystal phase in decreasing order of the spin-spin relaxation time T2s, the resin sheet has a difference ΔT2s,15min of 0.35 ms or more, being the difference between the relaxation time T2s,15min of the amorphous phase component of the resin sheet obtained from the measurement result of the relaxation time using pulsed NMR after dressing the polishing pad for 15 minutes, and the relaxation time T2s,dry of the amorphous phase component of the resin sheet obtained from the measurement result of the relaxation time using pulsed NMR in a dry state before dressing the polishing pad.

Description

Polishing pad and method of manufacturing the same

[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.

[0002] Because flatness is required for the surfaces of materials such as optical materials, semiconductor devices, hard disks, and glass substrates, polishing using a polishing pad is performed using a free abrasive method. The free abrasive method is a method of polishing the processed surface of the object to be polished while supplying a slurry (polishing liquid) containing abrasive particles between the polishing pad and the object to be polished. Polishing of semiconductor devices is performed using the so-called chemical mechanical polishing (CMP) method, which increases the mechanical polishing (surface removal) effect due to the relative movement of the abrasive and the object to be polished by the action of the chemical components contained in the polishing slurry, thereby obtaining a high-speed, smooth polished surface.

[0003] Polishing pads can be broadly divided into two types: polishing pads with a resin sheet formed by a wet film-forming method (soft polishing pads) as the polishing layer, and polishing pads (hard polishing pads) obtained by curing a prepolymer with a curing agent to form polyurethane (dry method) and slicing it. Soft polishing pads are softer than hard polishing pads because they contain numerous teardrop-shaped macro-bubbles within the resin sheet, making them suitable for use in 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 initial polishing of workpieces. On the other hand, polishing pads with a resin sheet formed by a wet film-forming method as the polishing layer are soft. Polishing pads used in polishing semiconductor devices and other devices require high levels of defect-free and planarization characteristics, and soft polishing pads are increasingly being used, particularly in finish polishing processes.

[0004] Since soft polishing pads are used for finish polishing, polishing pads that are less likely to cause scratches on 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, since the polyurethane resin constituting the polishing pad is generally hydrophobic, it does not mix well with the slurry, and 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 ethylene oxide repeating units pendant on the side chain, thereby introducing hydrophilic ethylene oxide repeating units into the surface of the polishing pad made of urethane resin. 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.

[0006] JP 2023-44910 A JP 2007-63323 A JP 2007-63324 A JP 2018-43342 A

[0007] In CMP technology, it is necessary to stabilize the polishing rate from the perspective of improving productivity and yield. In particular, since the polishing rate at the start of polishing is lower than the polishing rate at steady state, it is necessary to further shorten the time required for dummy polishing (start-up processing time) until the polishing rate becomes approximately constant. However, although the polishing pad of Patent Document 1 is a polishing pad with a resin sheet formed by a wet film-forming method as the polishing layer, it aims to reduce scratches by eliminating the film-forming aid, addressing the problem of agglomerates caused by residual film-forming aids, which in turn cause scratches, and does not recognize the problem of start-up processing time as an issue. The polishing pads of Patent Documents 2 and 3 are hard polishing pads formed by curing a prepolymer having repeating units of ethylene oxide in its side chain through a reaction with a curing agent (chain extender), and are not polishing pads containing 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 on the resin surface, and do not address the issue of shortening the start-up 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 rise time in polishing pads whose polishing layer is a resin sheet formed by a wet film-forming method. The present invention has been made in consideration of the above-mentioned problem, and aims to provide a polishing pad having excellent rise time in polishing pads whose polishing layer is a resin sheet formed by a wet film-forming method, and a method for manufacturing the same.

[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 measurement of the relaxation time using pulse NMR after dressing the polishing pad for 15 minutes. 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 The present inventors have found that a polishing pad having a rise time of 0.35 ms (milliseconds) or more has excellent rise time, and have completed the present invention. The present invention can 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, wherein a 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 [2] The polishing pad according to [1], wherein the resin sheet is a polyurethane sheet. [3] The polishing pad is dressed for five time periods of 15 minutes, 30 minutes, 60 minutes, 90 minutes, and 120 minutes, and the relaxation time T of the amorphous phase component obtained from the relaxation time measurement results using pulse NMR is 0.35 ms or more. 2s The standard deviation (S.D.) is the variation in the value of 2s,15-120min [4] The polishing pad according to [1] or [2], wherein the 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 is less than 0.05 ms. 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[5] The 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 amorphous phase component obtained from the measurement result of the relaxation time using pulse NMR to become 0.8 ms or more is 15 minutes or less.

[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.

[0010] This is a scanning electron microscope image of a resin sheet (polyurethane sheet) containing a plurality of teardrop-shaped bubbles formed by a wet film-forming method and a plurality of nearly spherical microbubbles smaller than the teardrop-shaped bubbles, which are interconnected. This is a diagram schematically showing a time-free induction decay signal curve measured by pulse 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 differences in spin-spin relaxation time. This is a diagram showing the change in the relaxation time of the amorphous phase component with respect to dressing time when the spin-spin relaxation time of the polishing pads of Examples 1 to 3 and Comparative Examples 1 and 2 was measured by pulse NMR after dressing. This is a diagram showing the change in the proportion of the amorphous phase component with respect to dressing time when the spin-spin relaxation time of the polishing pads of Examples 1 to 3 and Comparative Examples 1 and 2 was measured by pulse NMR after dressing. 1 is a graph showing the change in polishing rate relative to the number of processed wafers when TEOS (tetraethoxysilane) film-coated silicon wafers are polished using the polishing pads of Examples 1 to 3 and Comparative Examples 1 and 2. 2 is a graph showing the change in polishing rate relative to the number of processed wafers when TEOS (tetraethoxysilane) film-coated silicon wafers are polished using the polishing pads of Comparative Examples 1 and 2. 3 is a graph showing the change in polishing rate relative to the number of processed wafers when TEOS (tetraethoxysilane) film-coated silicon wafers are polished using the polishing pads of Examples 1 to 2 and Comparative Example 1. 4 is a graph showing the change in polishing rate relative to the number of processed wafers when TEOS (tetraethoxysilane) film-coated silicon wafers are polished using the polishing pads of Example 3 and Comparative Example 2. 5 is a graph showing the change in defect count relative to the number of processed wafers when Cu film-coated silicon wafers are polished using the polishing pads of Examples 1 to 3 and Comparative Example 1. 6 is a graph showing the results of measuring the components contained in the resin sheet of Comparative Example 1 by gas chromatography mass spectrometry (GC-MS). 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).

[0011] The following describes embodiments of the present invention. <<Polishing Pad>> The polishing pad of the present invention is a polishing pad including 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 a resin sheet by a wet film-forming method (bubbles that are anisotropic and have a structure in which the diameter increases from the top (the side in contact with the polished object) of the resin sheet to the bottom), and is used to distinguish them from 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 involves dissolving the resin to be formed into a film in an organic solvent, applying the resin-containing solution to a sheet-like substrate, and then passing the solution through a coagulation liquid that dissolves the organic solvent but not the resin to displace the organic solvent, solidifying the solution, and drying to form a foamed layer. Typically, when a resin sheet is produced using the wet film-forming method, multiple teardrop-shaped macro-bubbles (teardrop-shaped bubbles) are generated within the resin sheet. The dry molding method involves curing a prepolymer containing a urethane bond-containing polyisocyanate compound with a curing agent and a foaming agent to form a polyurethane. The foam is then sliced ​​into sheets to form a polishing pad. The polishing pad with a hard polishing layer produced using the dry molding method has relatively small, approximately spherical bubbles within the foam, so that the polishing surface of the polishing pad formed by slicing has pores (openings) that can retain slurry during polishing. The resin sheet with multiple teardrop-shaped bubbles may also contain multiple interconnected bubbles. The plurality of interconnected cells includes teardrop-shaped cells and a plurality of substantially spherical microbubbles smaller than the teardrop-shaped cells, which are interconnected with each other (see FIG. 1 ). In this specification and claims, the resin sheet is preferably a polyurethane sheet.A polyurethane sheet refers to a sheet whose main component is polyurethane resin (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 may be 100% by mass). This is clearly distinguishable from sheets whose main component is other resins (such as silicone resins). Furthermore, 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, a polishing layer refers to a layer having a surface (polishing surface) that comes into contact with a polished object such as a semiconductor device when polishing the object. The polishing pad of the present invention may have another layer, such as a cushion layer, on the opposite side of the polishing surface of the polishing layer.

[0012] <<Polishing Pad of First Aspect>> 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 is a polishing pad in which a free induction decay signal (FID) obtained by pulse NMR is subjected to a least squares method to determine a 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、15minIn this specification, the dressing of the polishing pad for measuring the relaxation time using pulsed NMR can be performed using a dresser and a slurry under the following dressing 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: 10 N. 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, and the polishing pad is dressed while the slurry is dripped onto the center of rotation of the polishing pad at a rate of 80 mL per minute. As the dresser, for example, a 3M Diamond Dresser, model number "A188," can be used. As the slurry, for example, a colloidal silica aqueous solution can be used. An example of such a solution is a colloidal silica aqueous solution with a colloidal silica stock solution (silica concentration 14-16 wt%):water ratio of 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 a liquid 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 a liquid 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] (Pulse NMR) Pulse NMR is also called TD-NMR. Pulse NMR measurements are performed using a pulse NMR spectrometer using the solid echo method, with a 90° pulse of 0.5 seconds, a repetition time of 4 seconds, 128 integrations, and a temperature of 40°C. The solid echo method is well known and will not be described in detail here; however, it is primarily used to measure samples with short relaxation times, such as glassy and crystalline polymers. A 90°x-τ-90°y pulse method, which applies two 90° pulses with a 90° phase difference to seemingly eliminate dead time, is used. When a 90° pulse is applied in the X-axis direction, a free induction decay (FID) signal is observed after the dead time. When a second 90° pulse is applied in the y-axis direction at the time τ during which the FID signal does not decay, the magnetization orientation aligns and an echo appears at t = 2τ. The obtained 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 pulsed NMR analysis results 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 can be performed. 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 interface phase (if it is difficult to separate the interface phase and the amorphous phase, it is analyzed as the interface phase). The amount (abundance ratio) of each component can be calculated using a calculation formula using Gaussian and Lorentzian functions (see, for example, "Analysis of 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 pulsed NMR as follows. First, a sample containing four samples cut into approximately 20 x 10 mm squares packed in a glass tube with a diameter of 1 cm is placed in a magnetic field. After a high-frequency pulse magnetic field is applied, the relaxation behavior of the macroscopic magnetization is measured, and a 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 obtained FID signal is proportional to the number of protons in the measurement sample. When the measurement sample contains three components, the FID signal appears as the sum of the response signals of the three components. On the other hand, since the components contained in the sample have different mobilities, the decay rate of the response signal differs between the components, resulting in different spin-spin relaxation times T2. Therefore, the sample can be divided into three components using the least squares method, and the components with the longest spin-spin relaxation times T2 are the amorphous phase, interface phase, and 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 mobility (crystalline phase component, interface phase component, and amorphous phase component). For fitting, BRUKER's analysis software "TD-NMR Analyzer" is used, 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. In this case, 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 with a single component (i.e., only the amorphous phase component), 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 by the fitting in the first step is subtracted from the FID signal of all three components in the measurement time section 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 Weibull coefficients W(1) = 2.0, W(2) = 1.0, and W(3) = 1.0, starting with the shorter relaxation time T2. The reason why the FID signals in the measurement time range of 0.15-2.0 ms were fitted using only the amorphous phase component in the first stage is that the amorphous phase component has a longer relaxation time than the crystalline phase component and the interface phase component (see Figure 2), and FID signals with measurement times of 0.15 ms or longer are thought to be derived from the amorphous phase component. By subtracting the waveform obtained in the first stage in the second stage, FID signals of only the crystalline phase and the interface phase are obtained. Therefore, by fitting using these two components, the waveforms of the crystalline phase component and the interface phase component can be more accurately determined. This analysis method is an analysis method that more clearly captures the characteristics of the amorphous phase component, which has a long relaxation time, by dividing the number of components used in fitting and the analysis range.

[0017] Formula 1 where I(t) represents the fitting strength 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 A resin sheet having a ΔT of 0.35 ms or more is used. 2s、15minis 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 start-up processability can be improved by using a resin sheet having the above properties is not necessarily clear, but can be assumed as follows. As described above, 1 The spin-spin relaxation time T2 observed by H-pulse NMR is the fastest in 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 adapted 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 By having the value of ΔT be within the above range, it is believed that in a shorter time after the slurry is dropped, many of the portions that were interfacial phase components before the slurry is dropped bond with water molecules derived from the slurry to become amorphous phase components, and the slurry becomes compatible with the resin sheet (penetrates into the resin sheet). This is presumably to improve start-up processability. Furthermore, by using a resin sheet with the above properties, defects such as scratches on the surface of the workpiece to be polished are less likely to occur. Furthermore, a high polishing rate can be obtained. ΔT 2s、15min There is no particular restriction on 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 in which 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. 2s、120min When ΔT is within the above range, a polishing pad with excellent start-up processability is easily obtained. 2s、120min There is no particular restriction on the upper limit, and it may be 0.60 ms or less, 0.55 ms or less, or 0.50 ms or less.

[0020] (S.D.(T 2s,15-120min In the first aspect of the present invention, the relaxation time T of the amorphous phase component obtained from the measurement results of the relaxation time 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 standard deviation (S.D.) is the variation in the value of 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. 2s,15-120min When S.D. (T) is within the above range, a polishing pad with excellent start-up processability is easily obtained. 2s,15-120min ) can be calculated using the following formula 2:

[0021] (Ratio (%) of amorphous phase component) In this specification, the abundance ratio of each phase of the crystalline phase, the interface phase (intermediate phase), and the amorphous phase may be referred to as A1, A2, and A3 (%), respectively. Generally, the lower the ratio of the amorphous phase, the harder the urethane becomes. Furthermore, the smaller the interface phase, the more clearly the crystalline phase and the amorphous phase are separated, and the more likely it is to have elastic properties that are less susceptible to distortion. Conversely, the more the interface phase, the less clearly the crystalline phase and the amorphous phase are separated, and the more likely it is to have delayed elastic properties. In the polishing pad of the first aspect of the present invention, the ratio of the amorphous phase component obtained from the measurement results of the relaxation time using pulse NMR after dressing the polishing pad for 15 minutes is preferably 55% or more (unit: mol%). The ratio of the amorphous phase component is more preferably 58% or more, even more preferably 60% or more, and even more preferably 62% or more. There is no particular limitation on the upper limit of the proportion of the amorphous phase component, 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 the amorphous phase component obtained from the measurement of the relaxation time 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 limitation on the upper limit of the proportion of the amorphous phase component, 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 obtained from the relaxation time measurement results using 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, polyester-based, polyether-based, or polycarbonate-based polyurethane resins can be used. Examples of polyester-based resins include polymers of polyester polyols such as ethylene glycol or butylene glycol (e.g., 1,4-butanediol) and adipic acid with diisocyanates such as diphenylmethane-4,4'-diisocyanate. Furthermore, polyols such as butanediol, trimethylolpropane, and triethanolamine may be further added to form polymers. Among these, a preferred polyester-based polyurethane resin is a polyurethane resin that is a condensate of polyester polyol obtained by dehydration condensation of 1,4-butanediol and adipic acid with 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-based 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-based resins include polymers of polycarbonate polyols with isocyanates, such as diphenylmethane-4,4'-diisocyanate. These resins may be commercially available, such as those sold under the trade name "Crisvon" by DIC Corporation, "Sunpren" by Sanyo Chemical Industries, Ltd., or "Rezamin" by Dainichiseika Color & Chemicals Mfg. Co., Ltd., or resins with desired properties may be produced in-house.

[0024] (Modulus) Modulus is an index representing 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, this may be referred to as the 100% modulus). The higher this value, the harder the resin is. Polyurethane resins preferably have 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 Derivative> The resin sheet preferably contains a cellulose derivative. By containing a cellulose derivative, the difference in relaxation time ΔT 2s,15min This increases the polishing pad's start-up processability. 2s,120min , S.D. (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 derivatives 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), are 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 of the amorphous phase component can be reduced. 2s,15min becomes larger, and ΔT 2s,15min It becomes easier to adjust ΔT to the above numerical range, and the rising processability of the polishing pad becomes easier to improve. 2s,120min , S.D. (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. 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 is thought to allow the hydrophilic surfactant in the resulting resin sheet to trap more water molecules in the slurry, allowing the slurry to adapt to the resin sheet in a short period of time. Until the slurry penetrates into the polishing pad and adapts, uneven adaptability occurs, making the polishing rate prone to instability. It is thought that the slurry's increased adaptability to the resin sheet suppresses uneven adaptability and shortens the time until the polishing rate of the polishing pad 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 ASISTOR SD-11 (trade name) manufactured by DIC Corporation.

[0027] <Solidification Regulator and / or Nonionic Surfactant> The resin sheet may contain a solidification regulator and / or a nonionic surfactant. Examples of solidification regulators include those composed only of carbon and hydrogen atoms (e.g., hydrocarbons having 8 to 18 carbon atoms), such as paraffinic regulators, aromatic regulators, naphthenic regulators, mineral oils, and synthetic oils. Among these, paraffinic regulators (e.g., isoalkanes) and polybutenes are preferred. For example, CRISBON ASISTER 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 a copolymer of ethylene oxide and propylene oxide, for example, CRISBON ASISTER SD-21 manufactured by DIC Corporation can be used.

[0028] <Other Surfactants> The resin sheet may contain surfactants other than those described above. Examples of other surfactants include carboxylic acid surfactants, sulfate ester surfactants, phosphate ester surfactants, ester surfactants, and alkanolamide surfactants.

[0029] <Polyol Compound> 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. There are no particular restrictions on the amount of polyol contained in the resin sheet, but it 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. Also, 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 limit to the upper limit of 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-mentioned components, the difference in relaxation time ΔT of the amorphous phase component can be reduced. 2s,15min becomes larger, and ΔT 2s,15minIt becomes easier to adjust ΔT to the above numerical range, and the rising processability of the polishing pad becomes easier to improve. 2s,120min , S.D. (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 the coagulation adjuster and / or nonionic surfactant are less hydrophilic than hydrophilic surfactants and have poor ability to trap water molecules, by using a polyol compound together with a cellulose derivative, the polyol compound is less likely to escape into the coagulation bath during production, and much of it is contained in the resin sheet. Therefore, even when a coagulation adjuster and / or nonionic surfactant is used, the polyol compound of the resin sheet can trap more water molecules in the slurry, and it is presumed that the slurry can be adapted to the resin sheet (the slurry penetrates into the resin sheet) in a short time, as in the case of using a hydrophilic surfactant. Until the slurry penetrates and adapts into the polishing pad, uneven adaptation occurs, making the polishing rate unstable. It is presumed that the slurry's increased 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 Components> In the polishing pad of the present invention, the resin sheet may contain components other than those described above, as long as the effects of the present invention are not impaired. Examples of other components include fillers such as carbon black.

[0031] (Thickness) The thickness of the resin sheet in the polishing pad of the present invention is not particularly limited, but can be, for example, in the range of 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. In buffing, the buffing is preferably performed on the skin layer side (polishing surface side) of the film-forming resin to ensure a uniform thickness. The amount of grinding 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 openings for retaining the slurry on the polishing surface can be secured. In addition, the resin sheet may be grooved, embossed, and / or perforated (punched), preferably embossed, on its polishing surface.

[0032] (Other Layers) The polishing pad of the present invention is based on the premise that the surface (polishing surface) of the resin sheet will contact the object to be polished, and therefore no other resin layer is present on the polishing surface of the resin sheet. On the other hand, the polishing pad of the present invention may have another resin layer (lower layer, support layer) attached to the surface opposite to the surface (polishing surface) of the resin sheet that polishes the object to be polished, or may not have another resin layer 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 the fine irregularities of the polishing table from affecting the shape of the polishing surface, and the polishing flatness is further improved. 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, improving workability.

[0033] <<Polishing Pad of Second Aspect>> The polishing pad of the second 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 a workpiece, wherein the resin sheet contains a cellulose derivative and a hydrophilic surfactant, or the resin sheet contains a cellulose derivative, a coagulation adjuster and / or a nonionic surfactant, and a polyol compound. The components in the polishing pad of the second aspect can be the same as those described for the polishing pad of the first aspect. Other aspects, such as thickness and buffing, can also be appropriately applied. By incorporating the above combination, the polishing pad of the present invention is likely to have 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. Therefore, it is believed that a large amount of them dissolves from the resin-containing solution composition into the coagulation liquid during the coagulation process, and almost none of them remains in the resin sheet after the coagulation process. In contrast, by using a cellulose derivative in combination with a hydrophilic surfactant or a polyol compound, the cellulose derivative promotes the formation of urethane resin crystal nuclei during the solidification process, and the hydrophilic surfactant or polyol compound is incorporated into the crystalline nuclei together with the resin before elution into the solidification solution, thereby increasing the amount of hydrophilic surfactant or polyol compound remaining in the resin sheet after the solidification process. This is thought to increase the hydrophilicity of the polishing layer of the polishing pad, making it easier to blend with the slurry even in the early stages of polishing, thereby improving the build-up properties. Furthermore, even when using a solidification adjuster or a nonionic surfactant, by combining it with a highly hydrophilic polyol compound and even in combination with a cellulose derivative, it is possible to ensure appropriate hydrophilicity while preventing elution into the coagulation bath, thereby maintaining a high level of hydrophilicity in the resin sheet after the solidification process. This is thought to make it easier to blend with the slurry even in the early stages of polishing, thereby improving the build-up properties. Furthermore, by having the above combination, the polishing pad of the present invention is less likely to cause defects such as scratches on the surface of the object to be polished.Furthermore, a high polishing rate can be obtained.

[0034] In addition, in the polishing pad of the second embodiment, when the free induction decay signal (FID) obtained by pulse NMR is subtracted by the least squares method in order from the component with the longest spin-spin relaxation time T2 and waveform separation is performed to separate the signal into three components, namely, an amorphous phase, an interface phase, and a crystalline phase, in order from the component with the longest spin-spin relaxation time T2, the relaxation time T2 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 is preferably 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. 2s、15min There is no particular restriction on 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 has an S.D. (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 result of the relaxation time using pulse NMR in a dry state before dressing the polishing pad. 2s,dry The difference between 2s,120min is preferably 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. 2s、120min There is no particular restriction on the upper limit, and it may be 0.60 ms or less, 0.55 ms or less, or 0.50 ms or less.

[0037] (Uses) 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, and glass. 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 also be suitably used for chemical mechanical polishing of objects to be polished using a polishing slurry. The polishing pad of the present invention 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] <<Method for manufacturing a polishing pad>> The method for manufacturing a polishing pad of the present invention can be manufactured by a conventionally known wet film-forming method. Preferably, the method for manufacturing a polishing pad includes a step of applying a resin solution composition containing 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 to a film-forming substrate, and a step of 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 Step> 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 derivative) 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. As the hydrophilic surfactant, the hydrophilic surfactants mentioned in the description of the polishing pad can be used. 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, relative to 100 parts by mass of the polyurethane resin.

[0043] (Solidification Adjuster) The resin solution composition may contain a solidification adjuster. As the solidification adjuster, the solidification adjusters mentioned in the description of the polishing pad can be used. The solidification adjuster 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, relative to 100 parts by mass of the polyurethane resin.

[0044] (Nonionic surfactant) 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 nonionic 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 polyurethane resin. Furthermore, the total amount of the coagulation regulator and the nonionic surfactant 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 polyurethane resin.

[0045] (Polyol Compound) The resin solution composition may contain a polyol compound. As the polyol compound, the polyol compounds mentioned in the description of the polishing pad can be used. 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 used without particular limitation as long as it can dissolve the polyurethane resin and is water-miscible. 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 or DMAc is 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% by mass, more preferably 10 to 40% by mass, and even more preferably 20 to 40% by mass. If the concentration is within the above range, the resin solution composition has appropriate fluidity and can be uniformly applied to the film-forming substrate in the subsequent coating process.

[0047] (Micropore Regulator / Density Adjuster) The resin solution composition may contain a micropore regulator or density adjuster in addition to the above components. Examples of the micropore regulator or density adjuster include water. The micropore regulator / 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 Components) 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 Step> The resin solution composition obtained above is continuously applied to a film-forming substrate at room temperature using, for example, a knife coater or reverse coater so as to be substantially uniform. The coating thickness (amount) of the resin solution composition can be adjusted by adjusting the clearance between the knife coater and the film-forming substrate. Any substrate commonly used in this technical field can be used as the film-forming substrate without 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 (e.g., a mixture of DMF and water) in advance to prevent the resin solution composition from penetrating into the film-forming substrate during application. Among these, polyester films are preferably used.

[0050] <Solidification Process> The film-forming substrate coated with the resin solution composition is immersed in a coagulation liquid primarily composed of water, a poor solvent for polyurethane resin. The resin solution composition is solidified to form a wet-film-formed resin sheet. Examples of the coagulation liquid include water and a mixed solution of water and a polar solvent such as DMF. Examples of polar solvents 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 or immersion time of the coagulation liquid; for example, immersion at 5 to 80°C for 5 to 60 minutes is sufficient. In the coagulation process, the coating film obtained in the coating process (the film-forming substrate coated with the resin solution composition) is immersed in a coagulation liquid (e.g., water or a solvent primarily composed of water) that is a poor solvent for polyurethane resin, and the coated film of the resin solution composition is solidified and regenerated into a sheet with numerous bubbles inside. In the coagulation liquid, a skin layer of several micrometers thick containing micropores is generally formed on the surface of the applied resin solution composition. Subsequently, as the organic solvent in the resin solution composition is replaced with the coagulation liquid, the polyurethane resin solidifies and regenerates 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 coagulation liquid. As a result, bubbles with larger pore diameters than the micropores formed in the skin layer (teardrop-shaped bubbles) are formed on the underside of the skin layer (the film-forming substrate side) and are approximately uniformly dispersed across the thickness of the sheet. However, the foam structure is not limited to this. The resulting sheet typically contains multiple interconnected bubbles. The interconnected bubbles include teardrop-shaped bubbles and multiple, approximately spherical microbubbles smaller than the teardrop-shaped bubbles, which are interconnected.

[0051] <Washing and Drying> After the coagulation step, the wet-film-formed resin sheet obtained by coagulation in the coagulation bath may be washed and dried, with or without being peeled off from the film-formation substrate. The washing treatment removes organic solvents remaining in the wet-film-formed resin sheet. An example of a washing liquid used for washing is water. After washing, the wet-film-formed resin sheet may be dried. The drying treatment 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 manufacturing 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 also be grooved, embossed, and / or perforated (punched), or the substrate may be bonded to the resin sheet. Furthermore, a light-transmitting portion may be provided on the resin sheet and / or polishing pad. The grinding method is not particularly limited, and grinding can be performed by a known method. Specific examples include grinding with sandpaper. The shape of the grooves and embossing is not particularly limited, and examples include lattice, concentric, and radial shapes. When bonding substrates to form a multilayer structure, multiple layers may be bonded and fixed together using double-sided tape or adhesive, with pressure applied as necessary. The double-sided tape and adhesive used here are not particularly limited, and can be selected from double-sided tapes and adhesives known in the art.

[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 includes a step of polishing an 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 using a holding pad. When using the polishing pad of the present invention, the polishing pad is attached to the polishing platen of a polishing machine so that the polishing surface of the resin sheet faces the object to be polished. Then, the polishing platen is rotated while supplying an abrasive slurry, polishing the processed surface of the object to be polished. Either a single-sided or double-sided polishing machine can be used as the polishing machine. Below, we will explain the polishing process using a single-sided polishing machine as a specific example. First, the object to be polished is held on the holding platen of the single-sided polishing machine. Next, the 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 object to be polished and the polishing pad, and the polishing platen or holding platen is rotated while pressing the object to be polished against the polishing pad at a predetermined polishing pressure, thereby polishing the object to be polished by chemical mechanical polishing. Examples of the object to be polished (held object) include semiconductor devices, semiconductor wafers, silicon, and glass. Among these, semiconductor devices are preferred. Materials for semiconductor devices include silicon, polysilicon, silicon oxide films, silicon nitride, and metals such as Cu, W, Al, Ta, and TiN. Methods for polishing the object to be polished include, for example, polishing the surface of the object to be polished using a polishing liquid (polishing slurry). Examples of polishing slurries include barrier metal slurries, oxide film slurries, and Cu slurries. The slurry may contain abrasive grains, an oxidizing agent, a polishing object protection component, an etching agent, a chelating agent, and the like. Examples of the abrasive grains in the polishing slurry include silica (SiO), alumina (AlO), and ceria (CeO). Among these, silica is preferred, and colloidal silica is more preferred. Furthermore, the liquid property of the polishing slurry may be an acidic slurry, a neutral slurry, or an alkaline slurry, but it is preferable that the slurry be an acidic slurry or an alkaline slurry in order to prevent aggregation of the abrasive grains and make it easier to disperse the abrasive grains.The liquid properties of the polishing slurry may be adjusted by adding to the above-mentioned slurry, as needed, an acidic component such as sulfuric acid or phosphoric acid, an alkali metal hydroxide such as sodium hydroxide, potassium hydroxide, rubidium hydroxide or cesium hydroxide, an organic alkali compound such as tetramethylammonium hydroxide or choline, or an alkaline component such as ammonia.

[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, "%" means "% by mass" and "parts" means "parts by mass" unless otherwise specified.

[0056] Example 1 A resin-containing solution was obtained by adding 40 parts by weight of DMF, 2 parts by weight of an anionic surfactant consisting of a sulfosuccinic acid alkyl ester sodium salt (trade name: CRISBON ASISTOR SD-11, manufactured by DIC Corporation), 2 parts by weight of acetyl cellulose (trade 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) having 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 component: 12.9 mol%) obtained by dehydration condensation of 1,4-butanediol and adipic acid with a chain extender of 1,4-butanediol / trimethylolpropane = 60 / 40 molar ratio and 4,4'-diphenylmethane diisocyanate (MDI). Next, prepare a PET film as a film-forming substrate, and use a knife coater to apply the above-mentioned resin solution thereto, and then immerse in a coagulation bath made of water, and then coagulate the resin-containing solution, and then wash and dry to obtain a resin film.The skin layer formed on the surface of the obtained resin film is subjected to a 100 μm buffing treatment, and obtain a polyurethane sheet with a thickness of 0.80 mm.Then, a PET substrate is attached to the back of the buffed surface via double-sided tape, and the buffed surface is embossed with a grid-shaped mold, and the double-sided tape with release paper is attached to the surface that is not embossed to fix it to the polishing table, to obtain a polishing pad.

[0057] Example 2 A resin-containing solution was obtained by adding 40 parts by mass of DMF, 2 parts by mass of an anionic surfactant consisting of sulfosuccinic acid alkyl ester sodium salt (trade name: CRISBON ASISTOR SD-11, manufactured by DIC Corporation), and 2 parts by mass of acetyl cellulose (trade name: L-20, manufactured by Daicel Corporation) to 100 parts by mass of an ester-based polyurethane resin solution (solids concentration: 30% by mass) having 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 component: 12.9 mol%) obtained by dehydration condensation of 1,4-butanediol and adipic acid with a chain extender of 1,4-butanediol / trimethylolpropane = 60 / 40 molar ratio and 4,4'-diphenylmethane diisocyanate (MDI). Next, a PET film is prepared as a film-forming substrate, and the resin solution is applied thereto using a knife coater, and then immersed in a coagulation bath made of water, and the resin-containing solution is coagulated, and then washed and dried to obtain a resin film.The skin layer formed on the surface of the obtained resin film is subjected to a 150 μm buffing treatment, and a polyurethane sheet having a thickness of 0.95 mm is obtained.Then, a PET substrate is attached to the back of the buffed surface via double-sided tape, and the buffed surface is embossed with a lattice-shaped mold, and a double-sided tape with release paper is attached to the non-embossed surface to fix it to a polishing platen, thereby 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 made of paraffin (trade name: CRISBON ASISTER SD-8i, manufactured by DIC Corporation), 2 parts by mass of a nonionic surfactant made 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 (solid content concentration 30% by mass) having 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 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 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 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, the buffed surface was embossed with a lattice-shaped mold, and a double-sided tape with release paper for fixing to a polishing platen was attached to the non-embossed surface to obtain 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 made of paraffin (trade name: CRISBON ASISTOR SD-8i, manufactured by DIC Corporation), 2 parts by mass of a nonionic surfactant made of a copolymer of ethylene oxide and propylene oxide (trade name: CRISBON ASISTOR SD-21, manufactured by DIC Corporation), 2 parts by mass of acetyl cellulose (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) having 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 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. Pulse NMR Analysis> The relaxation times and proportions of each component of the crystalline phase, interface phase, and amorphous phase in a polyurethane sheet were measured using pulse NMR as follows. First, four pieces of approximately 20 x 10 mm square polishing pad were cut, and after peeling off the release paper on the backside, the adhesive surfaces were bonded together to prepare two plate-shaped samples with both surfaces as polishing surfaces. A 1 cm diameter glass tube containing two plate-shaped samples was placed in a magnetic field, and the relaxation behavior of macroscopic magnetization after applying a high-frequency pulsed magnetic field was measured. As shown in Figure 2, a free induction decay (FID) signal was obtained (horizontal axis: time (msec), vertical axis: free induction decay signal). The initial value of the obtained FID signal is proportional to the number of protons in the measurement sample. If the measurement sample contains three components, the FID signal appears as the sum of the response signals of the three components. However, because the components contained in the sample have different mobilities, the decay rate of the response signal differs between the components, resulting in different spin-spin relaxation times T2. Therefore, it can be separated into three components using the least squares method, with the spin-spin relaxation time T2 being the longest, followed by the amorphous phase, interface phase, and crystalline phase (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 three components with different mobility (crystalline phase component, interface phase component, and amorphous phase component). For fitting, BRUKER's analytical software "TD-NMR Analyzer" is used, and the obtained relaxation curve is fitted using the following calculation formula 1 according to the product manual. The ratio of each component and the relaxation time are determined from the curve derived from the three components obtained by measurement. In this case, fitting is performed in two stages. In the first step, the FID signal in the measurement time interval of 0.15-2.0 ms is fitted with a single component (i.e., only the amorphous phase component), and the FID signal of the single component (amorphous phase component) in the interval of 0-2.0 ms is calculated (the FID signal of the single component (amorphous phase component) in the interval of 0-0.15 ms 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 section 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, the fitting is performed with Weibull coefficients W(1) = 2.0, W(2) = 1.0, and W(3) = 1.0, starting from the component with the shortest relaxation time T2. The reason why the FID signal in the measurement time section 0.15-2.0 ms in the first step was fitted with only the amorphous phase component is that the amorphous phase component has a longer relaxation time than the crystalline phase component and the interface phase component (see Figure 2), and therefore FID signals with measurement times of 0.15 ms or longer are thought to be derived from the amorphous phase component. In the second stage, the waveform obtained in the first stage is subtracted to obtain the FID signals of only the crystalline phase and the interface phase, and by fitting these two components, the waveforms of the crystalline phase component and the interface phase component can be obtained more accurately. This analysis method is an analysis method that can more clearly obtain the characteristics of the amorphous phase component, which has a long relaxation time, by dividing the number of components used in fitting and the analysis interval.

[0062] Formula 1 where I(t) is the fitting strength 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) Dried sample: The polishing pads of Examples 1 to 3 and Comparative Examples 1 and 2 were cut into approximately 20 x 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 x 10 mm square polishing pads) were placed in a 10 mmφ pulse NMR measurement sample tube to prepare pulse NMR measurement samples. Dressed sample: The 300 mmφ polishing pads of Examples 1 to 3 and Comparative Examples 1 and 2 were placed on the platen of a single-sided polisher FAM 12BS (manufactured by SpeedFam Co., Ltd.), and then dressed using colloidal silica slurry and a 100 mmφ diamond dresser (manufactured by 3M, model number A188) under the following dressing conditions. The dressing was performed for 5, 15, 30, 60, 90, and 120 minutes, and each dressed polishing pad was cut into a 20 × 10 mm square piece. The adhesive surfaces were then bonded together to prepare a plate-like sample. Two of the prepared plate-like samples (four 20 × 10 mm square polishing pads) were placed in a 10 mmφ pulsed NMR measurement sample tube to prepare the pulsed NMR measurement sample.

[0064] (Dressing 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, mixed solution of colloidal silica stock solution (silica concentration 14 to 16 wt%): water = 1:3 (mass ratio)) 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: 10 N Test time: 5, 15, 30, 60, 90, 120 minutes

[0065] (Relaxation Time of Amorphous Phase Components) In the dressing test, pulsed NMR measurements were performed on samples (dressed samples) that had been dressed for 5, 15, 30, 60, 90, and 120 minutes, and on samples (dry samples) that had not been subjected to the dressing test, and the measurements were analyzed by the method described in the "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 subjected to the dressing test were measured as T 2s,5min , T 2s,15min , T 2s,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]

[0067] (Ratio (%) of amorphous phase component) For the polishing pads of Examples 1 to 3 and Comparative Examples 1 and 2, the ratio of amorphous phase component of the polishing pad at each dressing time was determined based on the method described in "Pulse NMR analysis" above. The results are shown in Table 2 and FIG. 4.

[0068]

[0069] (ΔT2s, 15, ΔT2s, 120, SD (T2s, 15-120 min)) 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. ΔT 2s,15min : The difference ΔT between the relaxation time T2s,15min of the amorphous phase component in the sample dressed for 15 minutes and the relaxation time T2s,dry of the amorphous phase component in the sample not subjected to the dressing test 2s,120min: The difference between the relaxation time T2s, 120min of the amorphous phase component in the sample with a dressing time of 120 minutes and the relaxation time T2s, dry of the amorphous phase component in the sample without a dressing test, SD (T 2s,15-120min ): Variation of 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]

[0071] (Amount of Diethylene Glycol) To confirm that hydrophilic surfactants and polyol compounds are likely to remain in the resin sheet of the polishing pad 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 the weight of the sampled resin was measured. The sampled resin was then transferred to a vial and extracted with ethanol (3 mL of ethanol, extracted by leaving it on a hot plate at 70°C for 6 hours). The above procedure from collection to extraction was repeated three times, obtaining a total of approximately 9 mL of extract. Ethanol was added to the obtained extract to make it 10 mL. This extract after adding ethanol was diluted with acetone (HPLC-grade acetone with a small amount of tetradecane (an amount that approximates the peak amplitude of the target compound)) (extract:acetone = 2:1 (volume ratio)) to obtain a measurement sample. The measurement sample prepared as above was measured by gas chromatography-mass spectrometry, and the diethylene glycol (DEG) content (mg) was quantified. The results are shown in Figures 10 and 11.

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

[0073] 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. Although a very small amount of DEG was detected in Comparative Example 1, this is thought to be due to the DEG contained in the raw material.

[0075]

[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: 176 g / cm 2Slurry flow rate: 200 mL / min Dresser: 3M diamond dresser, model number "A189L" Conditioning: Ex-situ, 30 N, 4 scans Polishing time: 60 seconds Workpiece: TEOS-filmed silicon wafer and Cu-filmed silicon wafer Polishing slurry: Colloidal silica slurry (pH: 11.5, a mixture of colloidal silica stock solution (silica concentration 14 to 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 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 the slurry was dropped 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 calculating the average thickness of the TEOS film on the wafer before and after the polishing test from the 121 measurement results, and then 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]

[0080] From the polishing rate results obtained, the number of wafers required until the polishing rate stabilized (initial processing number) was calculated and evaluated according to the following criteria. A+ and A were rated as pass. The results are shown in Table 7. Evaluation criteria: A+: The initial processing number was 25 or less, A: The initial processing number was more than 25 to 75 or less, B: The initial processing number was more than 75 to 150 or less, C: The initial processing number was more than 150 to 250 or less, D: The initial processing number was more than 250.

[0081]

[0082] (Defect Performance Evaluation) For the Cu-film-coated silicon wafers after the polishing test, the second, fourth, sixth, eighth, twelfth, 27th, 52nd, and 77th polished wafers were subjected to 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 more. The results are shown in Table 8 and FIG. 9. The defect performance evaluation was also performed according to the following criteria, with A+ and A being considered acceptable. 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 20 or less. A: The average number of defects on the surface of the 2nd, 4th, 6th, 8th, 12th, 27th, 52nd, and 77th silicon wafers processed is more than 20 but less than 40. B: The average number of defects on the surface of the 2nd, 4th, 6th, 8th, 12th, 27th, 52nd, and 77th silicon wafers processed is more than 40.

[0083]

[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 (Figures 7 and 8), demonstrating excellent start-up processability. Furthermore, the polishing pads of Examples 1 to 3 also had fewer defects, demonstrating excellent start-up performance and defect reduction performance. It was also found that the polishing pads of Examples 1 to 3 had sufficiently high polishing rates and excellent polishing performance.

[0085] According to the present invention, a polishing pad having 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 a polishing surface for polishing an object to be polished, wherein the free induction decay signal (FID) obtained by pulsed NMR is fitted to the spin-spin relaxation time T by the least squares method. 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. 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 is dressed at each of five time points of 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 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. A polishing pad as described in claim 1 or 2, 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 within 15 minutes.

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