Polishing pad

Abstract

To provide a polishing pad which has excellent start-up performance from the initial stage of polishing, and has excellent stability of polishing rate.SOLUTION: A polishing pad includes a polyurethane sheet having a polishing surface that has a plurality of tear-shaped air bubbles and polishes an object to be polished, wherein when a ratio of the total area of openings per 11.7 mm2 area of an arbitrary cut surface obtained by cutting the resin sheet perpendicularly in a thickness direction is denoted as an opening ratio, A(%), an average opening diameter per 11.7 mm2 area in the arbitrary cut surface is denoted by B, and a distance in a thickness direction between the polishing surface and a cut surface where the average opening diameter B becomes maximum is denoted by X, a difference between a maximum value and a minimum value of the opening ratio A between the polishing surface of the resin sheet and the cut surface in a range of 0 to X is less than 10%, and the number of openings of the polishing surface is 2,000 or more per 12 mm2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polishing pad, and more particularly to a polishing pad for CMP of semiconductor devices. [Background technology]

[0002] To accurately form multilayer wiring, the surface of materials such as semiconductor wafers must be flat. Chemical mechanical polishing (CMP), a free-abrasive polishing method using a polishing pad, is typically used to flatten each layer. CMP uses a polishing solution (slurry) containing abrasive particles such as silica, anticorrosive agents, surfactants, etc. to modify the surface of the workpiece while enhancing the mechanical polishing effect of the abrasive particles. In CMP, the polishing solution containing abrasive particles penetrates between the workpiece and the polishing pad, allowing the polishing pad to rotate at high speed and polish the workpiece stably.

[0003] Polishing pads for semiconductor device manufacturing require perforations on the surface to hold the polishing slurry, hardness to maintain the flatness of the workpiece, and viscoelasticity to prevent scratches on the workpiece. To meet these requirements, polishing pads with polishing surfaces made from urethane resin foam are used.

[0004] Polyurethane resin foam is usually formed by curing a prepolymer containing a urethane bond-containing polyisocyanate compound with a curing agent (dry molding method).Then, this foam is sliced ​​into sheets to form a polishing pad.In the polishing pad with a hard polishing layer produced by this dry molding method (hereinafter sometimes abbreviated as hard polishing pad), approximately spherical bubbles are formed by water foaming, hollow bead addition, mechanical foaming, chemical foaming, etc., so that the polishing surface of the polishing pad formed by slicing has openings (openings) that can hold slurry during polishing. The use of hard polishing pads can improve the flatness and polishing rate of substrates. However, due to their hardness, there is a risk of defects such as scratches occurring. In addition, with the recent trend toward finer wiring widths, more precise polishing is required, and situations where hard polishing pads are difficult to meet are becoming more common. For this reason, polishing pads with soft polishing layers manufactured by wet film deposition methods (hereinafter sometimes referred to as soft polishing pads) are being used, particularly in the finishing process.

[0005] In CMP technology, it is desirable to stabilize the polishing rate from the viewpoint of improving productivity and yield. In particular, since the polishing rate at the start of polishing is generally lower than the polishing rate in a steady state, it is desirable to shorten the time it takes for the polishing rate to become substantially constant (called the start-up processing time), that is, to improve the start-up performance. Various studies have been conducted to shorten the start-up processing time (for example, Patent Document 1 and Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-75914 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-160474 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when polishing is continued using a conventional polishing pad, the opening diameter increases as the thickness of the polishing pad decreases, resulting in a significant decrease in the polishing surface and an unstable polishing rate. In addition, a polishing pad that can further shorten the start-up process time is desired.

[0008] The present invention has been made in view of the above problems, and has an object to provide a polishing pad that exhibits excellent start-up from the initial stage of polishing and excellent stability of the polishing rate. [Means for solving the problem]

[0009] The present invention includes the following aspects. [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, 11.7 mm of any cut surface obtained by cutting a resin sheet perpendicular to the thickness direction 2 The ratio of the total area of ​​openings per unit area is defined as the opening ratio A, and the area of ​​the cut surface of the arbitrary cut surface is defined as 11.7 mm. 2 Let B be the average opening diameter per unit area, and X be the distance in the thickness direction from the polished surface to the cutting surface when the average opening diameter B is maximum. The difference between the maximum and minimum values ​​of the opening ratio A in the cut surface within the range of 0 to X from the polished surface of the resin sheet is less than 10%, and The aperture of the polished surface is 12 mm 2 The polishing pad has 2000 or more particles per pad. [2] A polishing pad including a resin sheet having a plurality of teardrop-shaped bubbles and a polishing surface for polishing an object to be polished, The thickness of the resin sheet is T, and the cut surface of any cut surface obtained by cutting the resin sheet perpendicular to the thickness direction is 11.7 mm. 2 When the ratio of the total opening area per unit is defined as the opening rate A (%), The difference between the maximum value and the minimum value of the opening ratio A within a range of 0 to 0.75T from the polished surface of the resin sheet in the thickness direction is less than 10%, and The aperture of the polished surface is 12 mm 2 The polishing pad has 2000 or more particles per pad. [3] The polishing pad according to [1] or [2], wherein the polishing surface has been subjected to a grinding treatment. [4] A polishing pad according to any one of [1] to [3], wherein, when the thickness of the resin sheet is T, the maximum value of the opening ratio A within a range of 0 to 0.5T in the thickness direction from the polishing surface of the resin sheet is 40% or less. [5] The thickness of the resin sheet is T, and the cut surface of any cut surface obtained by cutting the resin sheet perpendicular to the thickness direction is 11.7 mm. 2 The polishing pad according to any one of [1] to [4], wherein the maximum value of the average opening diameter B within a range of 0 to 0.5T in the thickness direction from the polishing surface of the resin sheet is 200 μm or less, where B is the average opening diameter per hole. [6] The polishing pad according to any one of [1] to [5], wherein the resin sheet contains a polyurethane resin. [7] A polishing pad according to any one of [1] to [6], wherein when the polyurethane resin is separated into three components, namely an amorphous phase, an interfacial phase, and a crystalline phase, in order of the length of the spin-spin relaxation time T2, by subtracting the free induction decay signal (FID) obtained by pulse NMR in order of the length of the spin-spin relaxation time T2 by the least squares method and waveform separation, the proportion of the interfacial phase component at 20°C is less than 10%. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a polishing pad that exhibits excellent start-up from the initial stage of polishing and excellent stability of the polishing rate. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a photograph showing a cross section in the thickness direction of the polishing pad of Example 1. FIG. [Figure 2] 1 is a photograph showing a cross section in the thickness direction of a polishing pad of Comparative Example 1. FIG. [Figure 3] 1 is a diagram in which the depth from the polishing surface of the polishing pads of Example 1 and Comparative Example 1 is plotted on the horizontal axis and the average opening diameter on the vertical axis. [Figure 4] 1 is a diagram in which the depth from the polishing surface of the polishing pads of Example 1 and Comparative Example 1 is plotted on the horizontal axis and the opening ratio on the vertical axis. [Figure 5]1 is a diagram in which the depth from the polishing surface of the polishing pads of Example 1 and Comparative Example 1 is plotted on the horizontal axis and the numerical aperture per 12 mm 2 of the polishing surface on the vertical axis. [Figure 6] 1 is a plot diagram of the polishing pads of Example 1 and Comparative Example 1, with the horizontal axis representing the number of wafers polished and the vertical axis representing the polishing rate. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described. <Polishing pad> The polishing pad 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 surface to be polished, 11.7 mm of any cut surface obtained by cutting a resin sheet perpendicular to the thickness direction 2 The ratio of the total area of ​​openings per unit area is defined as the opening ratio A, and the area of ​​the cut surface of the arbitrary cut surface is defined as 11.7 mm. 2 Let B be the average opening diameter per unit area, and X be the distance in the thickness direction from the polished surface to the cutting surface when the average opening diameter B is maximum. The difference between the maximum and minimum values ​​of the opening ratio A in the cut surface within the range of 0 to X from the polished surface of the resin sheet is less than 10%, and The aperture of the polished surface is 12 mm 2 The polishing pad has 2000 or more particles per one particle.

[0013] <Resin sheet> The resin sheet has multiple teardrop-shaped bubbles. The term "teardrop-shaped bubbles" refers to bubbles formed within the resin sheet by a wet film-forming method (bubbles that are anisotropic and have a diameter that increases from the top to the bottom of the resin sheet (the side in contact with the substrate)). These bubbles are distinct from the roughly spherical bubbles formed in the polishing pad by a dry molding method. Therefore, the resin sheet of the present invention having multiple teardrop-shaped bubbles 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 solution to a sheet-like substrate, and then passing the resin through a coagulation liquid that dissolves the organic solvent but not the resin, replacing the organic solvent with the coagulation liquid. The resin is then solidified and dried to form a foamed layer. Typically, when a resin sheet is produced by a wet film-forming method, the escape route for the organic solvent inside the resin sheet to escape into the coagulation liquid becomes hollow, resulting in the formation of multiple roughly teardrop-shaped macrobubbles (teardrop-shaped bubbles). At this stage, the surface of the resin sheet is covered with a skin layer, but by subsequently grinding (buffing) the surface of the resin sheet, openings are exposed on the polished surface. This results in openings on the surface of the resin sheet opposite the substrate. The diameter of the openings formed on the surface of the resin sheet (opening diameter) is the smallest among the teardrop-shaped bubbles. The resin sheet preferably contains a polyurethane resin. The resin sheet is preferably a polyurethane sheet. In the present invention, a polyurethane sheet refers to a sheet containing polyurethane resin as a main component (50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more), and is clearly distinguished from sheets containing other resins (such as silicone resins) as a main component.

[0014] The polishing pad according to the first aspect of the present invention has a polishing surface for polishing an object to be polished, and has a cross section of 11.7 mm on any cut surface obtained by cutting a resin sheet perpendicular to the thickness direction. 2 The ratio of the total area of ​​openings per unit area is defined as the opening ratio A, and the area of ​​the cut surface of the arbitrary cut surface is defined as 11.7 mm. 2When the average opening diameter per polishing pad is B and the distance in the thickness direction from the polishing surface to the cut surface at which the average opening diameter B is maximum is X, the difference between the maximum and minimum values ​​of the opening ratio A at the cut surface within the range of 0 to X from the polishing surface of the resin sheet is less than 10%. In the present invention, the polishing surface means the surface of the polishing pad in a state before it is used. Therefore, the above X is the distance in the thickness direction from the polishing surface of an unused polishing pad. The "openings" in any cut surface obtained by cutting the resin sheet perpendicular to the thickness direction are the portions derived from the macro-bubbles in the resin sheet formed by the wet film forming method as described above. The "opening rate A" is the percentage of the openings in any cut surface of 11.7 mm. 2 Total area of ​​all openings per unit (mm 2 ) (total opening area) (unit: %). "Opening diameter" is defined as the equivalent circle diameter calculated from the area of ​​the opening, that is, the diameter when the opening is assumed to be a perfect circle. Note that the settings were made so that bubbles in contact with the boundary of the observation area were excluded during measurement. The cutoff value (lower limit) of the bubble diameter was set to 20 μm to exclude noise components. "Average opening diameter B" is the diameter of an arbitrary cut surface of 11.7 mm 2 It is the average diameter of the openings present in the area. As described above, conventional polishing pads lack stability in the polishing rate because the average opening diameter of the polishing surface increases as polishing proceeds. On the other hand, the polishing pad of the present invention is designed so that, although the openings of the polishing surface gradually increase as polishing proceeds, the difference between the maximum and minimum values ​​of the opening ratio until the average opening diameter reaches its maximum is smaller than that of conventional polishing pads. Therefore, the polishing pad of the present invention achieves a stable polishing rate even when polishing is continued. The average opening diameter and the opening ratio can be measured, for example, by a three-dimensional measuring X-ray CT device. The difference between the maximum and minimum values ​​of the aperture ratio is preferably less than 9%, and more preferably less than 8%.

[0015] The polishing pad according to the second aspect of the present invention has a polishing surface for polishing an object to be polished, and the thickness of the resin sheet is T. The resin sheet is cut perpendicularly to the thickness direction to obtain an arbitrary cut surface having a cross section of 11.7 mm. 2 When the ratio of the total area of ​​openings per unit area is defined as the opening ratio A, the difference between the maximum and minimum values ​​of the opening ratio A within a range of 0 to 0.75T from the polishing surface of the resin sheet in the thickness direction is less than 10%. Because the polishing pad of the present invention has a small difference between the maximum and minimum values ​​of the opening ratio A, a stable polishing rate is achieved even when the polishing pad is thin (for example, even when the thickness is about 0.5T). The difference between the maximum and minimum values ​​of the aperture ratio is preferably less than 9%, and more preferably less than 8%.

[0016] The polishing pad of the present invention has a polishing surface with an aperture of 12 mm. 2 This increases the retention of polishing slurry, thereby improving the stand-up of the polishing pad. 2 Preferably, the number of apertures per surface is 2100 or more, more preferably 2200 or more. There is no particular upper limit to the number of apertures on the polishing surface, but from the viewpoint of increasing the polishing rate, it is preferably 3000 or less, more preferably 2800 or less. Furthermore, from the viewpoint of improving the rising property of the polishing pad, the average aperture diameter of the polishing surface is preferably 40 μm or more. The numerical aperture of the polished surface can be measured using a 3D measurement X-ray CT device, a scanning electron microscope, or a microscope. 2 The numerical aperture per bubble can be calculated from the numerical aperture confirmed in the actual observation range. The cutoff value (lower limit) of the bubble diameter was set to 20 μm to eliminate noise components.

[0017] In the polishing pad of the present invention, when the thickness of the resin sheet is T, the maximum value of the opening ratio within a range of 0 to 0.5T in the thickness direction from the polishing surface of the resin sheet is preferably 40% or less. This allows for a greater improvement in the stability of the polishing rate, since there are many resin regions that contribute to polishing even when the resin sheet is thinned to half its original thickness by polishing. It is more preferable that the maximum value of the opening ratio within a range of 0 to 0.5T in the thickness direction from the polishing surface of the resin sheet is 39% or less. The maximum value of the opening ratio can be measured using the same method for measuring the opening ratio as described above.

[0018] The polishing pad of the present invention has a thickness of 11.7 mm on any cut surface obtained by cutting the resin sheet perpendicular to the thickness direction, where T is the thickness of the resin sheet. 2 When the average opening diameter per hole is B, the maximum value of the average opening diameter B within a range of 0 to 0.5T from the polished surface of the resin sheet in the thickness direction is preferably 200 μm or less. This allows for a greater amount of resin region that contributes to polishing even when the resin sheet is thinned to half its original thickness by polishing, thereby further improving the stability of the polishing rate. The maximum value of the average opening diameter B within a range of 0 to 0.5T from the polished surface of the resin sheet in the thickness direction is more preferably 190 μm or less, and even more preferably 180 μm or less. The maximum value of the average opening diameter can be measured by the method described above.

[0019] In order to reduce the difference between the maximum and minimum values ​​of the opening ratio of the polishing pad, for example, the skin layer may be made coarse (for example, by increasing the size of the air bubbles contained in the skin layer) or thin. When a sheet coated with a resin solution on a substrate is immersed in a coagulation bath, a dense skin layer first forms at the interface of the resin solution in contact with the coagulation liquid. Subsequently, solvent exchange between the organic solvent in the resin solution and the coagulation liquid proceeds through the skin layer, resulting in a solidified resin sheet regenerated on the substrate, forming multiple bubbles within the resin sheet. Because conventional skin layers are densely formed, solvent exchange proceeds relatively slowly, resulting in the average opening diameter of the resulting bubbles increasing from the surface toward the thickness. In contrast, forming a rough or thin skin layer facilitates penetration of the coagulation liquid into the resin sheet (rapid solvent exchange), resulting in the formation of teardrop-shaped bubbles with a smaller change in opening ratio toward the thickness than conventional methods. Methods for forming a rough or thin skin layer include, for example, adjusting the temperature of the coagulation bath, adjusting the composition of the coagulation liquid, and adjusting the resin composition contained in the resin sheet.

[0020] (Pulsed NMR) Pulse NMR can be measured at 20°C using a pulse NMR measurement device (JNM-MU25, 25 MHz, manufactured by JEOL Ltd.) by the solid echo method. The solid echo method is already well known, so we will not go into detail here; however, it is primarily used to measure samples with short relaxation times, such as glassy and crystalline polymers. A method that seemingly eliminates dead time is the 90°x-τ-90°y pulse method, in which two 90° pulses are applied with a 90° phase difference. When a 90° pulse is applied in the x-axis direction, a free induction decay (FID) signal is observed after the dead time. If a second 90° pulse is applied in the y-axis direction at time τ, when the FID signal does not decay, the magnetization orientation aligns and an echo appears at time t = 2τ. The resulting echo can be approximated to the FID signal after a 90° pulse. Methods for analyzing the relationship between physical properties, phase-separated structure, and composition from the results of pulsed NMR analysis are already well known. The free induction decay (FID) signal obtained by pulsed NMR can be separated into three components by subtracting the component with the longest spin-spin relaxation time T2 using the least-squares method and waveform separation. The component with the longest relaxation time is defined as the amorphous phase, with high mobility; the component with the shortest relaxation time is defined as the crystalline phase, with low mobility; and the intermediate component is defined as the interfacial phase (if it is difficult to separate the interfacial phase and the amorphous phase, it is analyzed as the interfacial phase). The amount of each component can be calculated using a formula using Gaussian and Lorentzian functions (see, for example, "Analysis of the Phase-Separated Structure of Polyurethane Resin by Solid-State NMR (High-Resolution NMR and Pulsed NMR)" (DIC Technical Review No. 12, pp. 7-12, 2006)).

[0021] The pulsed NMR measurement is described in detail below. First, a 1-cm-diameter glass tube is filled with a sample approximately 1–3 mm square, packed to a height of 1–2 cm, and placed in a magnetic field. After a high-frequency pulsed magnetic field is applied, the relaxation behavior of the macroscopic magnetization is measured, yielding a free induction decay (FID) signal (horizontal axis: time (μsec), vertical axis: free induction decay signal). The initial value of the FID signal is proportional to the number of protons in the sample. If the sample contains three components, the FID signal appears as the sum of the response signals of the three components. However, because the components in the sample have different mobilities, the decay rates of the response signals differ between the components, resulting in different spin-spin relaxation times, T2. Therefore, the sample can be separated into three components using the least-squares method. The components with the longest spin-spin relaxation times, T2, are the amorphous phase, the interface phase, and the crystalline phase, respectively. 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. For the above-mentioned pulse NMR, solid echo method, and spin-spin relaxation time T2, reference can be made to Japanese Patent Application Laid-Open No. 2007-238783 (particularly paragraphs

[0028] to

[0033] ).

[0022] When the resin sheet contains a polyurethane resin, the polyurethane resin is preferably separated into three phases, namely, an amorphous phase, an interfacial phase, and a crystalline phase, in descending order of the spin-spin relaxation time T2, by subtracting the free induction decay signal (FID) obtained by pulse NMR using the least squares method and waveform separation. The three phases are separated in descending order of the spin-spin relaxation time T2. The interfacial phase is the interface between the hard and soft segments. A low interfacial phase fraction indicates a clear interface between the hard and soft segments (clear phase separation between the hard and soft segments) and low compatibility between the hard and soft segments. Using such a polyurethane resin tends to reduce the difference between the maximum and minimum values ​​of the aperture ratio A at a cut surface within the range of 0 to X from the polished surface and the difference between the maximum and minimum values ​​of the aperture ratio within the range of 0 to 0.75T in the thickness direction from the polished surface to less than 10%. Although the mechanism behind this is unclear, it is thought that the urethane resin, which previously precipitated gradually from the surface layer toward the thickness direction when a resin sheet was immersed in a coagulation bath, can now be rapidly precipitated inside the resin sheet as well. The polyurethane resins may be used alone or in combination of two or more, but it is preferable to use one type alone.

[0023] There are no particular limitations on the means for reducing the abundance ratio of interfacial phase components in a polyurethane resin at 20°C to less than 10%, and examples include increasing the difference in polarity between the hard and soft segments of the polyurethane resin to facilitate separation. To increase the difference in polarity between the hard and soft segments, the materials, blending ratios, molecular weights, etc. of the polyol component, polyisocyanate component, and chain extender used may be appropriately adjusted. Specifically, for example, when a polyester polyol obtained by dehydration condensation of a diol and a dibasic acid is used as the polyol component, the longer the diol chain (the greater the number of carbon atoms between hydroxyl groups), the lower the polarity, and the easier it is for the polyisocyanate component to separate from the highly polar hard segment. Furthermore, the higher the blending ratio of the polyisocyanate component (especially MDI), the higher the polarity of the hard segment, facilitating separation from the soft segment. Furthermore, using a diol with a low carbon number as a chain extender increases the polarity of the hard segment, facilitating separation from the soft segment.

[0024] The soft segment preferably contains a polyester polyol. Because polyester polyols have a high coagulation value, they do not easily form a dense skin layer and facilitate interdiffusion between the coagulation liquid (e.g., water) and the solvent (e.g., DMF). In the present invention, the coagulation value refers to the amount of water (ml) required to gel the polyurethane resin and reach a point where the opacity does not disappear when a diluted resin-containing solution is prepared by diluting the resin-containing solution with the solvent used in the subsequent resin-containing solution so that the resin content of the solution becomes 1% by mass, and then adding a poor solvent at 25°C dropwise to 100 g of this solution while adjusting the temperature to 25°C and stirring with a stirrer.

[0025] The polyol component is not particularly limited, and various polyol components can be used, such as polyether diol, polyester diol, polycarbonate diol, etc., with polyester diol being preferred. One type of polyol component may be used alone, or two or more types may be used in combination.

[0026] The polyether diol is not particularly limited, and various polyether diols can be used. Preferred examples of polyether polyols include poly(ethylene glycol), poly(propylene glycol), poly(tetramethylene glycol), and poly(methyltetramethylene glycol). One type of polyether polyol may be used alone, or two or more types may be used in combination.

[0027] The polyester diol is not particularly limited, and various polyester diols can be used. Examples of preferred polyester diols include polyester diols obtained by directly esterifying or transesterifying a dicarboxylic acid or an ester-forming derivative thereof, such as an ester or anhydride, with a low-molecular-weight diol. Examples of the dicarboxylic acid include aliphatic carboxylic acids having 4 to 12 carbon atoms, such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, 2-methylsuccinic acid, 2-methyladipic acid, 3-methyladipic acid, 3-methylpentanedioic acid, 2-methyloctanedioic acid, 3,8-dimethyldecanedioic acid, and 3,7-dimethyldecanedioic acid; and aromatic dicarboxylic acids, such as terephthalic acid, isophthalic acid, and orthophthalic acid. Examples of the low molecular weight diol include aliphatic diols such as ethylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol; and alicyclic diols such as cyclohexanedimethanol and cyclohexanediol. The carbon number of the low molecular weight diol is preferably 2 to 12. One type of polyester diol may be used alone, or two or more types may be used in combination.

[0028] When a polyester diol is used as a polyol component, it is preferable to reduce the content of low-molecular-weight diol contained in the polyester diol from the viewpoint of reducing interfacial phase components in the polyurethane resin. During the polymerization of an ester-forming derivative such as a dicarboxylic acid with a low-molecular-weight diol, a significant amount of low-molecular-weight diol is contained as a by-product of an equilibrium reaction. Because this low-molecular-weight diol behaves as a hard segment in the polyurethane resin, the hard segment is dispersed among the soft segment. As a result, the interface (interfacial phase components) between the hard segment and the soft segment increases. From the viewpoint of reducing interfacial phase components in the polyurethane resin, the number average molecular weight of the polyol component is preferably in the range of 700 to 10,000, more preferably in the range of 800 to 7,500, and even more preferably in the range of 1,000 to 5,000. When the number average molecular weight is within the above range, clear separation of the hard segment and the soft segment is likely to occur, and the interfacial phase components are likely to be reduced.

[0029] (Polyisocyanate component) The polyisocyanate component is not particularly limited, and various polyisocyanate components can be used. Examples of the polyisocyanate component include aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate (MDI), phenylene diisocyanate, and xylylene diisocyanate; aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylylene diisocyanate; and prepolymers obtained by reacting a polyisocyanate component with a polyol component in advance to obtain a high molecular weight. Among these, aromatic diisocyanates are preferred, and 4,4'-diphenylmethane diisocyanate is more preferred.

[0030] From the viewpoint of reducing the interfacial phase components of polyurethane resins, the polyisocyanate component is preferably 4,4'-diphenylmethane diisocyanate with a reduced oligomer content. 4,4'-Diphenylmethane diisocyanate (MDI) is commercially available and easily available, but it is highly reactive and begins to gradually produce oligomers by self-polymerization immediately after production, so commercially available products generally contain a certain amount of oligomers. If MDI containing oligomers is used as a raw material in the production of polyurethane resins, the aggregation of hard segments is inhibited, making it difficult to reduce the interfacial phase components. The oligomer content in MDI is not particularly limited, but is preferably, for example, 0.5% by mass or less. The method for reducing the content of oligomers in MDI is not particularly limited, and known purification methods can be used, such as distillation, recrystallization, reprecipitation, and filtration, with filtration being preferred from the viewpoint of efficiency.

[0031] (Chain extender) The chain extender is not particularly limited, and various chain extenders can be used. Examples of the chain extender include propylene glycol, 1-ethyl-1,2-ethanediol, 1,2-dimethyl-1,2-ethanediol, 1-methyl-2-ethyl-1,2-ethanediol, 1-methyl-1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-dimethyl-1,2-propanediol, 1,3-dimethyl-1,3-propanediol, 2,2-dimethyl-1, 3-Propanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 1-methyl-1,4-butanediol, 2-methyl-1,4-butanediol, 2,3-dimethyl-1,4-butanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,5-pentanediol, 3-ethyl-1,5-pentanediol Examples of suitable chain extenders include aliphatic polyol compounds such as pentanediol, 2,4-dimethyl-1,5-pentanediol, 3-methyl-1,6-hexanediol, 2-methyl-1,8-octanediol, 2,7-dimethyl-1,8-octanediol, 2-methyl-1,9-nonanediol, 2,8-dimethyl-1,9-nonanediol, ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, hexamethylene glycol, sucrose, methylene glycol, glycerin, and sorbitol; aromatic polyol compounds such as bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, and hydroquinone; and water. These chain extenders may be used alone or in combination of two or more. From the viewpoint of reducing interfacial phase components in the polyurethane resin, the chain extender preferably contains 50 to 100% by weight of a linear, short-chain chain extender having a number average molecular weight of 250 or less. The chain extender is preferably a low-molecular-weight diol having 2 to 6 carbon atoms, more preferably ethylene glycol or 1,4-butanediol. These chain extenders can increase the cohesive force of the hard segments, which tends to reduce interfacial phase components.

[0032] (Other ingredients) The polyurethane resin may or may not contain, in addition to the above components, inorganic fillers such as carbon black, film-forming stabilizers, surfactants, etc., as long as the effects of the present invention are not impaired. While inorganic fillers such as carbon black improve the polishing rate, they also cause polishing defects, so it is preferable that the polyurethane sheet contains a small amount of inorganic filler, more preferably 5% by mass or less (preferably 3% by mass or less, more preferably 1% by mass or less), and even more preferably no inorganic filler is contained. Furthermore, it is preferable that the polyurethane sheet contains a small amount of carbon black, and it is more preferable that the amount of carbon black is 5% by mass or less (preferably 3% by mass or less, and more preferably 1% by mass or less), and it is even more preferable that the polyurethane sheet does not contain any carbon black.

[0033] The polyurethane sheet in the polishing pad of the present invention has a polishing surface for polishing an object to be polished. In the polishing pad of the present invention, the polishing surface and / or the surface opposite to the polishing surface of the polyurethane sheet may be ground (buffed) or not, but it is preferable that the polishing surface of the polyurethane sheet be ground, which results in the presence of many openings originating from microbubbles on the polishing surface, and the openings can hold the slurry, thereby improving the polishing rate. The polishing pad of the present invention may have grooves, embossing, and / or holes (punching) on ​​the polishing surface of the polyurethane sheet. The polishing pad of the present invention may have a light-transmitting portion. The polishing pad of the present invention may have a single-layer structure consisting of only a polyurethane sheet, or may have a multi-layer structure in which a substrate is attached to the surface of the polyurethane sheet opposite the polishing surface. Examples of the substrate include substrates made of nonwoven fabric, PET, and vinyl chloride. While there are no particular limitations on the properties of the substrate, it is preferable that the substrate be harder than the polyurethane sheet (for example, have a higher A hardness or D hardness). By providing a layer harder than the polyurethane sheet, the polishing pad can be prevented from expanding, contracting, or bending when polishing an object to be polished.

[0034] The polishing pad of the present invention is used for polishing optical materials, semiconductor devices, glass substrates for hard disks, etc., and is particularly suitable for chemical mechanical polishing (CMP) of devices in which an oxide layer or barrier metal layer and a metal layer such as copper are formed on a semiconductor wafer.

[0035] <Polishing Pad Manufacturing Method> The polishing pad of the present invention can be manufactured by a method for manufacturing a polishing pad, which includes, for example, a step of preparing a resin solution containing a polyurethane resin, a step of applying the resin solution to a film-forming substrate, and a step of immersing the film-forming substrate to which the solution has been applied in a coagulation liquid to coagulate the solution. Each step will be described below.

[0036] (Step of preparing a resin solution) In this step, a polyurethane resin is dissolved in a water-miscible organic solvent to prepare a resin solution containing the polyurethane resin. As the polyurethane resin, those mentioned above can be used. Examples of the organic solvent include N,N-dimethylformamide (DMF), methyl ethyl ketone, N,N-dimethylacetamide (DMAc), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), acetone, and 1,3-dimethyl-2-imidazolidinone (DMI). One or more of the organic solvents may be used. Among these, DMF or DMAc is preferred. The solid content of the resin solution is not particularly limited, but is preferably 15 to 50 mass %, more preferably 15 to 40 mass %, and even more preferably 20 to 35 mass %. When the solid content is within the above range, the resin solution has appropriate fluidity, making it easy to apply the resin solution uniformly to the film-forming substrate. The resin solution may contain components other than the above components as long as the effects of the present invention are not impaired.

[0037] (Process for applying a resin solution to a film-forming substrate) The resin solution obtained above is continuously applied to the film-forming substrate so as to be approximately uniform using a coating machine such as a knife coater, a reverse coater, etc. At this time, the thickness of the coating film can be adjusted by adjusting the gap (clearance) between the film-forming substrate and the die or knife of the coating machine. The film-forming substrate can be any substrate commonly used in this technical field without any particular limitation, and examples thereof include flexible polymer films such as polyester films and polyolefin films, nonwoven fabrics impregnated with elastic resins, etc. Among these, polyester films are preferably used.

[0038] (Process for solidifying the resin solution) The substrate coated with the resin solution is immersed in a coagulation liquid (coagulation bath) whose main component is water, which is a poor solvent for polyurethane resin, to coagulate and regenerate the polyurethane resin. The coagulation liquid may be water or a mixed solvent of water and a polar organic solvent such as DMF. Examples of the polar organic solvent include the water-miscible organic solvents used to dissolve the polyurethane resin, such as DMF, DMAc, THF, DMSO, NMP, acetone, and DMI. The concentration of the polar organic solvent in the mixed solvent is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, and even more preferably 0 to 5% by mass. If the coagulation liquid contains a small amount of polar organic solvent, a rough or thin skin layer is likely to be formed. The coagulation liquid is preferably water or a mixed solvent of water and DMF, and more preferably a mixed solvent of water and DMF. The temperature of the coagulation liquid is not particularly limited, but is preferably 10 to 40° C., more preferably 15 to 25° C. A temperature in this range makes it easier to form a rough or thin skin layer. The immersion time is also not particularly limited, but is preferably 5 to 120 minutes.

[0039] Thereafter, the coagulated and regenerated polyurethane sheet is peeled off from the resin sheet, or is washed and dried without being peeled off. The washing treatment removes the organic solvent remaining in the polyurethane sheet. The washing liquid used for washing includes water. After washing, the polyurethane sheet is dried by a conventional method, for example, by drying in a dryer at 80 to 150°C for about 5 to 60 minutes.

[0040] It is preferable that the polishing surface of the polyurethane sheet be ground (buffed) and the surface opposite the polishing surface be not ground (buffed). Leaving the polishing surface open improves polishing start-up, while leaving the surface opposite the polishing surface unopened prevents slurry from seeping in through the open polishing surface, preventing the polishing layer from peeling off from the substrate. The polishing surface of the polyurethane sheet may also be grooved, embossed, and / or perforated (punched), or a substrate may be attached to the surface opposite the polishing surface. There are no particular limitations on the grinding method, and known methods such as grinding using sandpaper, grinding using a buffing machine or a slicing machine can be used. Among these, using a buffing machine or a slicing machine is preferred because it allows for obtaining a polyurethane sheet with a substantially uniform thickness. There are no particular limitations on the shape of the grooves and embossing, and examples thereof include lattice, concentric circle, and radial shapes. When a substrate is attached to a polyurethane sheet to form a multilayer structure, the multiple layers may be bonded and fixed together using double-sided tape, adhesive, etc., while applying pressure as necessary. There are no particular restrictions on the double-sided tape or adhesive used in this case, and any double-sided tape or adhesive known in the art may be selected and used. [Example]

[0041] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0042] (polishing pad manufacturing) Example 1 A polyurethane resin-containing solution was obtained by adding 55 parts by weight of DMF and 2 parts by weight of a nonionic surfactant consisting of a polyether resin / silicone resin mixture (7 / 3 by weight, product name: CRISBON ASISTOR SD-7, manufactured by DIC Corporation) to 100 parts by weight of a DMF solution containing a 30% solids concentration of polyester-based polyurethane resin with a 100% modulus of 7.2 MPa. The mixture was then stirred to obtain a polyester-based polyurethane resin. The polyester-based polyurethane resin was obtained by condensing a polyester polyol obtained by dehydration condensation of ethylene glycol, propylene glycol, and adipic acid, followed by vacuum distillation at 120°C to 140°C for several hours to adjust the content of low-molecular-weight diol components of 160 or less to 1.3 mol%, with a chain extender of 1,4-butanediol / trimethylolpropane in a molar ratio of 97 / 3, and 4,4'-diphenylmethane diisocyanate (MDI). Next, a PET film was prepared as a substrate for film formation. The resin-containing solution was applied to the film using a knife coater, and the film was immersed in a coagulation bath containing DMF and water in a 95:5 mass ratio at 18°C ​​for 60 minutes to coagulate the resin-containing solution. The film was then washed and dried to obtain a resin film. The skin layer formed on the surface of the resulting resin film was subjected to a 12 μm buffing treatment to obtain a 0.80 mm thick polyurethane sheet. Double-sided tape was then attached to the back of the buffed surface, and the buffed surface was embossed with a grid-shaped mold to obtain a polishing pad.

[0043] Comparative Example 1 A polyurethane resin-containing solution was obtained by adding 55 parts by weight of DMF and 2 parts by weight of a nonionic surfactant consisting of a polyether resin / silicone resin mixture (7 / 3 by weight, product name: CRISBON ASISTOR SD-7, manufactured by DIC Corporation) to 100 parts by weight of a DMF solution containing a 30% solids concentration of polyester-based polyurethane resin with a 100% modulus of 7.0 MPa. The polyester-based polyurethane resin was obtained by condensing a polyester polyol (used without distillation, containing 12.9 mol% low-molecular-weight diol components with a molecular weight of 160 or less) obtained by dehydration condensation of 1,4-butanediol and adipic acid with a chain extender of 1,4-butanediol / trimethylolpropane in a 60 / 40 molar ratio with 4,4'-diphenylmethane diisocyanate (MDI). Next, a PET film was prepared as a substrate for film formation. The resin-containing solution was applied to the film using a knife coater, and the film was immersed in a coagulation bath of water at 18°C ​​for 60 minutes to coagulate the resin-containing solution. The film was then washed and dried to obtain a resin film. The skin layer formed on the surface of the resulting resin film was buffed to a thickness of 3 μm to obtain a polyurethane sheet with a thickness of 0.80 mm. Double-sided tape was then attached to the back of the buffed surface, and the buffed surface was embossed with a grid-shaped mold to obtain a polishing pad.

[0044] (Aperture ratio and difference between its maximum and minimum values) The difference between the maximum and minimum values ​​of the opening ratio in the thickness (X) from the polished surface to the cut surface where the average opening diameter is maximum was determined using a three-dimensional measuring X-ray CT device in the following manner. A 3D X-ray CT image was obtained at a 50 μm interval parallel to the surface (perpendicular to the thickness direction) from the polished surface of the polishing layer to the surface opposite the polished surface of the polishing layer using a 3D measurement X-ray CT device (Yamato Scientific Co., Ltd. TDM1000H-II (2K)). The obtained tomographic images were then binarized using image processing software (Volume Graphics VG Studio MAX 3.0) to distinguish between the bubble portion and the resin portion, and the circular equivalent diameter, i.e., the opening diameter, was calculated from the area of ​​each opening, assuming that the opening was a perfect circle. The arithmetic mean of the opening diameters of each opening was then determined as the average opening diameter (μm). The area of ​​the opening relative to the total area of ​​the opening and the remaining resin portion was determined as the opening ratio (%). Among the obtained tomographic images, the position at which the tomographic image with the largest average opening diameter was obtained was defined as the thickness direction distance (X) from the polished surface to the cut surface at which the average opening diameter was largest, and the difference between the maximum and minimum opening ratios was calculated by subtracting the opening ratio of the tomographic image with the smallest opening ratio from the opening ratio of the tomographic image with the largest opening ratio among the tomographic images from the polished surface to the thickness direction distance (X). Furthermore, the thickness of the resin sheet is defined as T, and the difference between the maximum and minimum values ​​of the aperture ratio within the range of 0 to 0.75T in the thickness direction from the polished surface of the resin sheet was calculated by subtracting the aperture ratio of the tomographic image with the minimum aperture ratio from the aperture ratio of the tomographic image with the maximum aperture ratio among the above-mentioned tomographic images within the range of 0 to 0.75T in the thickness direction from the polished surface of the resin sheet.

[0045] (Numerical aperture of polished surface) The numerical aperture of the polished surface was calculated by counting the numerical aperture of the tomographic image (surface image) of the polished surface, that is, the 0 mm thickness of the above tomographic image. 2 The actual measured aperture is 11.7mm 2 The value was calculated by converting the number of pieces per unit.

[0046] (Maximum aperture ratio up to 0.5T) The maximum aperture ratio from the polished surface to half the thickness (0.5T) of the resin sheet was determined from the largest aperture ratio among the above-mentioned tomographic images from the polished surface to half the thickness (0.5T) of the resin sheet.

[0047] (Maximum average opening diameter up to 0.5T) The maximum value of the average opening diameter from the polished surface to half the thickness (0.5T) of the resin sheet was determined to be the largest value among the average opening diameters of each of the above tomographic images from the polished surface to half the thickness (0.5T) of the resin sheet.

[0048] The measurement conditions for the three-dimensional measurement X-ray CT device were: number of views per rotation: 1200, number of frames / view: 10, X-ray tube voltage: 30 kV, tube current: 0.2 mA, magnification axis position: 30 mm, reconstruction pixel size X: 0.008355 mm, reconstruction pixel size Y: 0.008355 mm, reconstruction pixel size Z: 0.008355 mm, number of pixels: 512 × 512 pixels, field of view: 4.32 mm × 4.32 mm, aperture measurement range: 3.35 mm × 3.50 mm (11.7 mm 2 ), and cutoff value (lower limit): 20 μm.

[0049] (Pulse NMR measurement) The resulting polishing pad was subjected to pulsed NMR measurement under the following conditions. Specifically, sample pieces of approximately 1 to 3 mm square were cut from the land portion of the ground polishing pad with a cutter, filled into a 10 mm diameter sample tube to a height of 1 to 2 cm, and pulsed NMR measurement was performed to obtain an attenuation curve. To ensure that the obtained attenuation curve and the fitting curve matched, analysis was performed by the least squares method using a Lorentz function (linear portion) and a Gaussian function (curved portion), and the proportions (abundance ratios (mass%)) of the amorphous phase, interface phase, and crystalline phase in the polishing layer, as well as the relaxation time (T2), were determined. The fitting and analysis were performed using the software attached to the measurement device described below. [Measurement conditions] Equipment: JNM-MU25 manufactured by JEOL Ltd. Measurement magnetic field strength: 0.58T Observation frequency: 25MHz Observed nucleus: 1H Measurement: Spin-spin relaxation (T2) Measurement method: Solid Echo method Pulse width: 2.2 μs Pulse interval: 13.0 μs Pulse repetition time: 4.0 seconds Accumulation count: 16 times Measurement temperature: 20℃

[0050] (Polishing test) Using the obtained polishing pad, 400 silicon wafers with TiN (titanium nitride) film (blanket wafers with a 1.5 μm thick TiN film formed on a silicon substrate) were polished under the following conditions, and the stability and start-up of the polishing rate were evaluated.

[0051] [Polishing conditions] Polishing machine used: Ebara Corporation, product name "F-REX300X" Grinding pressure: 3.1psi Abrasive: CuBM slurry Abrasive temperature: room temperature Dresser: 3M diamond dresser, model number "A188" Object to be polished: 300mmφTiN Pad break: 30N x 30 minutes, surface plate rotation speed 80 rpm, ultrapure water 500 mL / min Conditioning: Ex-situ 30N, 4 scans, 16 seconds Polishing: Platen rotation speed 90 rpm, head rotation speed 91 rpm, slurry flow rate 300 mL / min, polishing time 60 seconds

[0052] (Stability of polishing rate) For 1 to 400 TiN-coated wafers, the thickness was measured at 121 points before and after polishing, and the average value was calculated. The thickness measured at each point was then divided by the polishing time to calculate the polishing rate (Å / min). The thickness was measured using an optical film thickness and film quality measuring device (KLA-Tencor Corporation, trade name "ASET-F5x", measurement: DBS mode). Of the 400 film-coated wafers polished, the maximum, minimum, average and standard deviation of the polishing rates for 20 to 150 wafers were determined, and the polishing rate fluctuation was evaluated using the following formula. The lower the polishing rate fluctuation value, the higher the stability of the polishing rate was evaluated. Polishing rate fluctuation (%) = (maximum polishing rate - minimum polishing rate) / average polishing rate x 100

[0053] (Standing up ability) Whether the polishing rate at the initial stage of polishing quickly stabilized was evaluated as follows. The polishing rate relative to the number of wafers polished was tracked, and the number of wafers polished at the point where no increase in the polishing rate was observed was defined as the "initial number of wafers processed." The smaller this "initial number of wafers processed," the more quickly the polishing rate stabilized. The results are shown in Table 1 and FIGS.

[0054] [Table 1]

[0055] 3 is a plot of the average opening diameter at each depth position of the polishing pads of Example 1 and Comparative Example 1, with the horizontal axis representing the depth when the polishing surface is defined as 0 and the vertical axis representing the average opening diameter at each depth position. For the polishing pads of Example 1 and Comparative Example 1, the thickness direction distance X from the polishing surface to the cut surface at which the average opening diameter was maximum was 0.60 mm and 0.50 mm, respectively. Furthermore, in Example 1 and Comparative Example 1, when the thickness of the resin sheet is defined as T, the maximum average opening diameter within a range of 0 to 0.5T (0.4 mm in both the Examples and Comparative Examples) in the thickness direction from the polishing surface of the resin sheet was 128 μm and 208 μm, respectively. 4 is a plot of the aperture ratio at depth for the polishing pads of Example 1 and Comparative Example 1, with the horizontal axis representing the depth when the polishing surface is defined as 0 and the vertical axis representing the aperture ratio at that depth. For the polishing pad of Example 1, the minimum aperture ratio was 28.17% and the maximum aperture ratio was 34.98%, with a difference of 6.81, until the average aperture diameter reached its maximum (up to a thickness of 0.60 mm). The maximum aperture ratio within a range of 0 to 0.5T (0 to 0.4 mm) in the thickness direction from the polishing surface of the resin sheet was 34.5%. For the polishing pad of Comparative Example 1, the minimum aperture ratio was 28.17% and the maximum aperture ratio was 42.30%, with a difference of 15.13, until the average aperture diameter reached its maximum (up to a thickness of 0.5 mm). FIG. 5 shows the measurement range of 11.7 mm for the polishing pads of Example 1 and Comparative Example 1, with the horizontal axis representing the depth when the polishing surface is set to 0. 2 The polishing surface of the polishing pads of Example 1 and Comparative Example 1 is 11.7 mm. 2 The number of apertures per aperture was 2331 and 819, respectively. 6 is a plot of the number of wafers polished on the horizontal axis and the polishing rate on the vertical axis for the polishing pads of Example 1 and Comparative Example 1. The polishing pad of Example 1 had a relatively large numerical aperture on the polishing surface, and therefore the number of wafers required to polish the pad until the polishing rate became almost constant was only 15, showing excellent start-up properties. However, the polishing pad of Comparative Example 1 did not stabilize its polishing rate until the number of wafers polished reached 150.

[0056] Furthermore, as can be seen from Table 1, the polishing pad of Example 1 had excellent stability of polishing rate, since the difference between the maximum and minimum values ​​of the opening ratio until the average opening diameter reached its maximum was less than 10%. [Industrial Applicability]

[0057] The polishing pad of the present invention has excellent start-up properties from the initial stage of polishing and excellent stability of the polishing rate, and therefore has industrial applicability.

Claims

1. A polishing pad including a resin sheet having a plurality of teardrop-shaped bubbles and having a polishing surface for polishing an object to be polished, A cut surface of 11.7 mm on any cut surface obtained by cutting the resin sheet perpendicular to the thickness direction 2 The ratio of the total area of ​​the openings per 11.7 mm of the cut surface of the arbitrary cut surface is defined as the opening ratio A (%). 2 When the average opening diameter per hole is B and the distance in the thickness direction from the polished surface to the cut surface when the average opening diameter B is maximum is X, The difference between the maximum and minimum values ​​of the opening ratio A in the cut surface within the range of 0 to X from the polished surface of the resin sheet is 6.81% or more and less than 10%, and The aperture of the polished surface is 12 mm 2 The number of pieces is 2,000 or more and 3,000 or less per piece, However, the opening diameter of the polishing pad is 20 μm or more.

2. The polishing pad of claim 1 , wherein the polishing surface has been subjected to a grinding treatment.

3. 3. The polishing pad according to claim 1, wherein the maximum value of the opening ratio A within a range of 0 to 0.5T in the thickness direction from the polishing surface of the resin sheet is 40% or less, where T is the thickness of the resin sheet.

4. 4. The polishing pad according to claim 1, wherein the maximum value of the average opening diameter B within a range of 0 to 0.5T in the thickness direction from the polishing surface of the resin sheet is 200 μm or less.

5. 5. The polishing pad according to claim 1, wherein the resin sheet comprises a polyurethane resin.

6. 6. The polishing pad according to claim 5, wherein when the polyurethane resin is separated into three components, an amorphous phase, an interface phase, and a crystalline phase, in order of decreasing spin-spin relaxation time T2, by subtracting the free induction decay signal (FID) obtained by pulse NMR in order of decreasing spin-spin relaxation time T2 by the least squares method, the abundance ratio of the interface phase component at 20°C is less than 10%.

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