Grinding method for grinding pad and workpiece

Abstract

The abrasive pad of the present invention comprises an abrasive layer containing hydrolyzable resin and abrasive grains. After being immersed in ion-exchange water at 80°C for 3 hours, the pencil hardness of the aforementioned abrasive layer at 25°C and 60%RH is lower than that of the aforementioned abrasive layer at 25°C and 60%RH before immersion, and the difference in pencil hardness of the aforementioned abrasive layer at 25°C and 60%RH before and after immersion is 3 levels or more.

Description

Technical Field

[0001] This invention relates to an abrasive pad and an abrasive method for abrasive objects. Prior Technology

[0002] In the polishing process of substrates used in semiconductor devices, a method using a fixed abrasive polishing pad is known. This fixed abrasive polishing pad has an polishing layer containing an adhesive resin and abrasive grains fixed thereon. As the aforementioned adhesive resin, cured products of curable resins such as phenolic resin, epoxy resin, and acrylic phenolic resin have conventionally been used (see, for example, Patent Document 1).

[0003] In recent years, from the perspective of reducing environmental pollution, attempts have been made to simply bury the grinding pads in the soil after disposal, allowing them to decompose through microorganisms. Therefore, grinding pads using biodegradable resins as adhesive resins are being researched (for example, see Patent Documents 2 and 3). [Previous Technical Documents] [Patent Literature]

[0004] Patent Document 1: Japanese Patent Application Publication No. 2018-51733 Patent Document 2: U.S. Patent Application Publication No. 20050101228 Patent Document 3: Japanese Patent Application Publication No. 2005-305570 Summary of the Invention

[0005] The problem that the invention aims to solve Furthermore, coarse grinding using a fixed abrasive grinding pad (sometimes simply referred to as "grinding") is performed using abrasive grains exposed on the surface of the grinding pad. During grinding, abrasive grains may detach from the grinding pad, or wear and tear may cause abrasive grain passivation (a state where the leading edge of the abrasive grain wears down and flattens), thus reducing the number of abrasive grains available for grinding and decreasing the grinding ability of the grinding pad. Therefore, it is desirable to achieve a structure where the adhesive resin on the grinding surface of the grinding pad is appropriately eliminated, allowing the abrasive grains to detach appropriately, while simultaneously allowing new abrasive grains to protrude, thereby creating a structure where abrasive grains are always exposed without any passivation.

[0006] However, according to the research of the inventors, it has been clarified that in the abrasive pads of Patent Documents 2 and 3, even if the adhesive resin decomposes, the decomposed adhesive resin is difficult to remove from the abrasive surface of the abrasive pad. Therefore, it was found that it is difficult to expose new abrasive grains without abrasive passivation, and the abrasive speed tends to decrease.

[0007] The present invention was made in view of the above circumstances, and its object is to provide a grinding pad that is easy to remove the decomposed adhesive resin and has a small decrease in grinding speed, and a grinding method for the workpiece using the pad. Technical means to solve the problem

[0008] This invention relates to the following grinding pad and grinding method for the workpiece.

[0009] [1] An abrasive pad comprising an abrasive layer containing hydrolyzable resin and abrasive particles, wherein after being immersed in ion-exchange water at 80°C for 3 hours, the pencil hardness of the aforementioned abrasive layer at 25°C and 60%RH is lower than the pencil hardness of the aforementioned abrasive layer at 25°C and 60%RH before immersion, and the difference between the pencil hardness of the aforementioned abrasive layer at 25°C and 60%RH before and after immersion is 3 levels or more. [2] The abrasive pad described in [1] has a pencil hardness of 2H or higher at 25°C and 60%RH before impregnation. [3] As described in [1] or [2], the scratches on the abrasive pads that have been immersed in ion-exchange water at 80°C for 3 hours are cohesive damage when a pencil with a higher hardness than the pencil hardness of the aforementioned abrasive pad at 25°C and 60%RH after immersion are used in a pencil hardness test. [4] The abrasive pad described in any of [1] to [3], wherein the median particle size of the aforementioned abrasive grains is less than 30 μm. [5] The abrasive pad described in any of [1] to [4], wherein the content of the aforementioned abrasive particles in the aforementioned abrasive layer is more than 1% by mass and less than 55% by mass relative to the total mass of the aforementioned abrasive layer. [6] The abrasive pad described in any of [1] to [5], wherein the content of the aforementioned hydrolyzable resin in the aforementioned abrasive layer is more than 20% by mass and less than 98.5% by mass relative to the total mass of the aforementioned abrasive layer. [7] The abrasive pad described in any of [1] to [6], wherein the aforementioned hydrolyzable resin is mainly composed of glycolic acid polymer. [8] The abrasive pad described in any of [1] to [7], wherein the aforementioned abrasive layer further contains a hydrolysis accelerator. [9] The abrasive pad described in [8] contains at least one selected from the group consisting of carboxylic anhydrides, phosphorus compounds, cyclic esters and basic metal oxides.

[10] The abrasive pad described in any of [1] to [9], wherein the thickness of the aforementioned abrasive layer is more than 0.1 mm and less than 30 mm.

[11] The abrasive pad described in any of [1] to

[10] , wherein the density of the aforementioned abrasive layer is more than 1.57 g / cm3 and less than 3.00 g / cm3.

[12] A grinding method for a workpiece, comprising the following procedure: while supplying a water-containing grinding liquid to the surface of the grinding layer of a grinding pad as described in any of [1] to

[11] , the grinding pad and the workpiece are slid relative to each other to grind the workpiece. Invention efficacy

[0010] According to the present invention, a grinding pad that easily removes the decomposed adhesive resin and has a small decrease in grinding speed, and a grinding method for grinding objects using the same pad, are provided. Simple Explanation of the Diagram

[0011] [Figure 1] is a schematic cross-sectional view showing a grinding method for a workpiece according to one embodiment of the present invention. [Figure 2] is a laser microscope image of the test piece before impregnation of the abrasive pad 1 and after immersion in ion-exchange water at 80°C for 3 hours, and after pencil hardness tests at various hardness levels. [Figure 3] is a laser microscope image of the test piece before impregnation of the abrasive pad 7 and after immersion in ion-exchange water at 80°C for 3 hours, and after pencil hardness tests at various hardness levels. [Figure 4] is an explanatory diagram illustrating the observation area using a laser microscope. [Figure 5A] is the measurement image before image processing, and [Figure 5B] is the measurement image after image processing. [Figures 6A to 6C] are schematic diagrams illustrating the image processing sequence. [Figure 7] shows the measurement results of the contour on the straight line passing through the origin O and point A in Figure 5B. Implementation

[0012] From the viewpoint of stabilizing abrasive grains and obtaining the desired grinding performance, it is desirable for the grinding layer to have a hardness of at least a specified value. On the other hand, the inventors have discovered that, in order to facilitate the removal of decomposed hydrolyzable resin (adhesive resin), it is desirable for the surface hardness of the grinding layer to decrease and become brittle after a specified period of contact with the grinding fluid.

[0013] Specifically, it was found that if the difference in pencil hardness of the abrasive layer before and after immersion in ion-exchange water at 25°C and 60%RH for 3 hours is greater than 3, the abrasive grains can be stably maintained during grinding, and the decomposed hydrolyzed resin is easily removed by the shear force during grinding, resulting in less decrease in grinding speed. Furthermore, the pencil hardness of the abrasive layer before and after immersion, as described later, can be adjusted by the type and content of the hydrolyzed resin, the type and content of the hydrolysis accelerator, and the median particle size of the abrasive grains.

[0014] The following is a detailed description of one embodiment of the present invention. However, the present invention is not limited to this embodiment. In addition, in this specification, the numerical range indicated by "to" means the range of values ​​recorded before and after "to" as the lower limit and upper limit values. [ ] [1.] [Abrasive Pad]

[0015] The abrasive pad of this embodiment includes an abrasive layer containing hydrolyzable resin and abrasive grains. That is, the abrasive layer includes a base material containing hydrolyzable resin and abrasive grains fixed by the base material. [ ] [1-1.] [Abrasive Layer]

[0016] As described above, the pencil hardness of the abrasive layer after immersion in ion-exchange water at 80°C for 3 hours at 25°C and 60%RH is lower than that of the abrasive layer before immersion at 25°C and 60%RH. Furthermore, the difference in pencil hardness between the abrasive layer before and after immersion in ion-exchange water at 80°C for 3 hours is 3 levels or more.

[0017] If the difference in pencil hardness before and after impregnation is 3 or more, the abrasive grains can be stably maintained during grinding, and the brittle layer formed by the decomposed hydrolyzed resin can be easily removed by the shear force during grinding. Therefore, the decrease in grinding speed can be reduced. From the same point of view, the difference in pencil hardness between the abrasive layer before and after impregnation in ion-exchange water at 80°C for 3 hours is preferably 6 or more, and more preferably 8 or more. The upper limit of the difference in pencil hardness before and after impregnation is, for example, 13 or less.

[0018] Furthermore, in this instruction manual, pencil hardness is evaluated using 14 levels: 6B, 5B, 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, and 6H. Here, if the pencil hardness before impregnation is 6H and the pencil hardness after impregnation is F, then the difference in pencil hardness before and after impregnation (before impregnation - after impregnation) is the difference between 6H and F, which is level 6. Specifically, when the pencil hardness before impregnation is 6H and the pencil hardness after impregnation is F, the hardness of the pencil after impregnation is set to 1, and numbers (levels) are assigned sequentially up to the pencil hardness before impregnation, namely F(1), H(2), 2H(3), 3H(4), 4H(5), 5H(6), and 6H(7). Then, the value 7-1=6 obtained by subtracting the level assigned to the pencil hardness after impregnation from the level assigned to the pencil hardness before impregnation "7" is defined as the "difference in pencil hardness".

[0019] When conducting pencil hardness tests within the range of 6B to 6H, there are no particular restrictions on the pencil hardness of the abrasive layer before impregnation at 25°C and 60%RH, as long as it meets the aforementioned pencil hardness difference. However, it is preferable, for example, to be 2H or higher (i.e., 2H or higher hardness). If the pencil hardness of the abrasive layer before impregnation is 2H or higher, the retention of abrasive grains by the hydrolyzable resin is better, resulting in better abrasive performance as an abrasive pad. From the same point of view, the pencil hardness of the abrasive layer before impregnation is preferably 4H or higher, and more preferably 6H. For example, the pencil hardness of the abrasive layer before impregnation is preferably 4H or higher but less than 6H (a pencil hardness of any one of 4H, 5H, or 6H).

[0020] On the other hand, the pencil hardness of the abrasive layer after immersion in ion-exchange water at 80°C for 3 hours at 25°C and 60% RH is not particularly limited as long as it meets the aforementioned pencil hardness difference, but it is preferably 3H or lower (i.e., 3H or lower hardness). Near the surface of the abrasive layer after immersion, a brittle layer of decomposed hydrolyzable resin is formed. If the pencil hardness of this brittle layer is 3H or lower, it is easier to remove by the shear force during abrasion, thus exposing the unpassivated abrasive grains more easily, further suppressing the decrease in abrasion speed. From the same perspective, the pencil hardness of the abrasive layer after immersion is preferably F or lower, and even more preferably B or lower. From the viewpoint of suppressing excessive collapse due to rapid decomposition, the lower limit of the pencil hardness of the abrasive layer after immersion can be 6B or higher. For example, the pencil hardness of the abrasive layer after immersion is preferably 6B or higher and F or lower (pencil hardness is any one of 6B, 5B, 4B, 3B, 2B, B, HB, and F).

[0021] The hardness of the pencil before and after impregnation can be measured in the following order. Specifically, a center O is set on the abrasive pad, and the radius (distance) from center O to the end of the abrasive pad (abrasive layer) is set to 1. Next, a circle with a radius of 0.6 is drawn with center O as the center. Two points on this circle are set at positions that divide the circle into two equal parts, and 10 mm × 10 mm pieces are cut out from each point to prepare two test pieces. However, when the abrasive pad has grooves, it is preferable to avoid cutting the test pieces to prevent affecting the pencil hardness test results. For one of the test pieces, the pencil hardness (h0) before impregnation is measured under conditions of 25°C and 60% RH. Next, another test piece was immersed in ion-exchange water at 80°C for 3 hours, and then dried in a drying chamber at a dew point temperature of -40°C for 1 hour. For the dried test piece, the pencil hardness (h1) of the test piece surface after immersion was measured using the same method as above.

[0022] In addition, except for the following points, the above pencil hardness test can be generally carried out according to JIS K 5600-5-4:1999. (1) Since the test piece has a thickness, a plate-shaped component with a thickness equivalent to it is laid under the testing machine and fixed with double-sided tape so that the pencil lead is at the same height as the test piece. (2) The observation position of the scratch is set as the starting position of the test. (3) In order to make the scratches clear and easy to observe, the pencil hardness test should be carried out after the pencil is set up and left to stand for 2 minutes.

[0023] The pencil hardness of the abrasive layer can be adjusted by the type and content of the hydrolyzable resin, the type and content of the hydrolysis accelerator, and the median particle size of the abrasive grains. For example, if glycolic acid polymer is used as the hydrolyzable resin, the pencil hardness before impregnation tends to be higher, while the pencil hardness after impregnation tends to be lower. Furthermore, if carboxylic anhydride is used as the hydrolysis accelerator, or the content of the hydrolysis accelerator is increased, or the median particle size of the abrasive grains is increased, the pencil hardness after impregnation tends to be lower.

[0024] Furthermore, it is preferable to immerse the pencil in ion-exchange water at 80°C for 3 hours, and then perform the same pencil hardness test using a pencil with a harder hardness than the pencil after the abrasive layer is immersed. The resulting scratches are considered cohesive damage. For example, if the pencil after the abrasive layer is immersed has a hardness of B, then the next higher hardness level is HB. In this case, it is preferable to confirm the scratches after performing the pencil hardness test using a pencil with a hardness of HB. By performing the pencil hardness test using a pencil with a harder hardness than the pencil after the abrasive layer is immersed and confirming the scratches, the mode of damage can be determined.

[0025] Cohesive failure refers to scratches left after resin is removed, which differs from plastic deformation where only the resin deforms. Here, the pencil hardness test is performed more than twice, and cohesive failure is defined as the occurrence of scratches showing signs of cohesive failure in more than 80% of the test counts (or all test counts if the number of test counts is 2 to 4). If the scratches show signs of cohesive failure, it indicates that a brittle layer has formed on the surface of the abrasive layer, making it easily removed by the shear force during abrasion. Scratches can be observed visually at the starting point of the pencil hardness test.

[0026] Whether agglomerative failure is present can be determined by examining the area around the scratch created by the pencil hardness test at the start of the test. This is similar to the solid portion that appears to bulge from the surface of the abrasive layer, as seen in plastic deformation. For example, if the depth of the deepest part of the pencil scratch is D, and the height of the highest point of the bulge from the surface of the abrasive layer is H, then when H / D is less than 1.0, it can be considered agglomerative failure. D, H, and H / D can be measured using a laser microscope (e.g., Keyence VK-X260).

[0027] Figure 4 is an explanatory diagram illustrating the observation area using a laser microscope. Figure 5A is the measurement image before image processing, and Figure 5B is the measurement image after image processing. Figures 6A to 6C are schematic diagrams showing the image processing sequence. Figure 7 shows the measurement results of the contour along the straight line passing through the origin O and point A in Figure 5B. Specifically, when the field of view is divided into two equal parts, the lower half of which includes the scratch at the start of the experiment, is observed using a laser microscope with a 20x magnification objective lens (e.g., Nikon) and an NA of 0.46 (see Figures 4, 5A, and 6A). Furthermore, in Figure 4, the area enclosed by the outermost thin line represents the field of view, and the width of the field of view (length along the x-axis, described later) is set to approximately 700 μm. Next, a reference plane is estimated for the entire field of view using the least squares method. Then, all height data is rotated to make this reference plane horizontal, adjusting it so that the height of the reference plane is 0 (see Figures 5B and 6B). Furthermore, the setting of the reference plane using the least squares method and the adjustment to make the reference plane height 0 can be performed by analyzing the measurement results using image processing software (e.g., a multi-file analysis application (Keyence VK-H1XM)). Here, the deepest point of the scratch at the start of the test is taken as the origin O. A straight line passing through the origin O and perpendicular to the direction of the pencil hardness test is set as the x-axis, and a straight line passing through the origin O and perpendicular to the x-axis is set as the y-axis (see Figure 4). The absolute value of the height from the origin O to the reference plane is set as D (see Figure 6C). In addition, the highest point in the area (enclosed by the thick line) of the scratch observation area (filled part) on the y-axis that includes the origin O and the area (non-filled part) extending approximately 200 μm into the direction of pencil travel is set as point A (see Figure 4). The absolute value of the height from the reference plane to point A is set as H (see Figure 6C). In addition, when the scratches of the same depth at the start of the test cover a wide area, making it impossible to observe the scratches and raised areas simultaneously, D and H can be obtained by performing image linking and conducting the same measurements as described above. In addition, if cracks are observed on the surface after immersion in ion-exchange water at 80°C for 3 hours, it can be determined that the surface is obviously embrittled due to the formation of an embrittlement layer, and therefore the scratches are caused by coagulation damage.

[0028] If a brittle layer of decomposed hydrolyzed resin forms on the impregnated abrasive layer, scratches are prone to agglomeration damage. This is especially true when cracks or fissures are observed on the surface of the impregnated abrasive layer. Because the molecular weight of the hydrolyzed resin forming the abrasive layer is reduced, the surface is in a state of brittle layer formation, making scratches prone to agglomeration damage. For example, if glycolic acid polymers are used as the hydrolyzed resin, a brittle layer is easily formed on the impregnated abrasive layer, making scratches prone to agglomeration damage. Furthermore, if carboxylic anhydrides are used as hydrolysis accelerators, or the content of hydrolysis accelerators is increased, or the median particle size of the abrasive grains is increased, a brittle layer is easily formed on the impregnated abrasive layer, making scratches prone to agglomeration damage.

[0029] The following is an explanation of the components contained in the polishing layer. [ ] [1-1-1:] [Hydrolyzable resin]

[0030] There are no particular limitations on the type of hydrolyzable resin, as long as it exhibits hydrolytic properties. Examples of hydrolyzable resins include polyester, polycarbonate, and polyamide. Among these, polyester is preferred, and aliphatic polyester is even more preferred, considering its good hydrolytic properties.

[0031] Aliphatic polyesters can be obtained by homopolymerization or copolymerization of hydroxycarboxylic acids and / or lactones, esterification of aliphatic dicarboxylic acids and aliphatic diols, copolymerization of aliphatic dicarboxylic acids and aliphatic diols and hydroxycarboxylic acids and / or lactones.

[0032] Examples of hydroxycarboxylic acids include aliphatic hydroxycarboxylic acids with 2 to 8 carbon atoms, such as glycolic acid, lactic acid, malic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvalerate, hydroxyhexanoic acid, hydroxyheptanoic acid, and hydroxyoctanoic acid.

[0033] Examples of lactones include propiolactone, butiolactone, valproic acid lactone, and ε-caprolactone, which have 3 to 10 carbon atoms.

[0034] Examples of aliphatic dicarboxylic acids include: oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, and other aliphatic saturated dicarboxylic acids with 2 to 8 carbon atoms; and maleic acid, trans-butenedioic acid, and other aliphatic unsaturated dicarboxylic acids with 4 to 8 carbon atoms.

[0035] Examples of aliphatic diols include: ethylene glycol, propylene glycol, butanediol, hexanediol, and other alkyl diols with 2 to 6 carbon atoms; polyethylene glycol, polypropylene glycol, polybutanediol, and other polyalkyl diols with 2 to 4 carbon atoms.

[0036] These components can be used individually or in combination of two or more. In addition, aliphatic polyesters that are hydrolyzable may further contain structural units derived from aromatic dicarboxylic acids such as terephthalic acid, aromatic diols such as bisphenol A, and aromatic hydroxycarboxylic acids such as hydroxybenzoic acid.

[0037] Preferably, the polymer contains structural units derived from hydroxycarboxylic acids, and more preferably, lactic acid polymers or glycolic acid polymers. Glycolic acid polymers are preferred due to their high strength and ease of molecular weight reduction through hydrolysis, which facilitates the formation of an brittle layer. That is, the hydrolyzable resin preferably contains glycolic acid polymers as a main component. "Containing glycolic acid polymers as a main component" means that, relative to the total mass of the hydrolyzable resin, the content of glycolic acid polymers is 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0038] Glycolic acid polymers are polymers comprising structural units (-(-O-CH2-CO-)-) derived from glycolic acid. Glycolic acid polymers can be homopolymers of glycolic acid or copolymers of glycolic acid with monomers that can copolymerize with it.

[0039] Examples of monomers that can be copolymerized include: hydroxycarboxylic acids other than glycolic acid, lactones, aliphatic dicarboxylic acids, aliphatic diols, aromatic dicarboxylic acids, aromatic diols, and aromatic hydroxycarboxylic acids.

[0040] The content of glycolic acid-derived structural units in the glycolic acid polymer relative to the total mass of the structural units constituting the glycolic acid polymer is preferably 50% by mass or more, more preferably 75% by mass or more, further preferably 90% by mass or more, even more preferably 95% by mass or more, and most preferably 99% by mass or more. If the above-mentioned content of glycolic acid-derived structural units is 50% by mass or more, the strength of the glycolic acid polymer can be further improved, thus obtaining more sufficient strength when used in abrasive pads.

[0041] While the weight-average molecular weight of the hydrolyzable resin varies depending on its type, it is preferably between 70,000 and 500,000. If the weight-average molecular weight of the hydrolyzable resin is 70,000 or higher, its strength can be further improved, thus further enhancing abrasive grain retention and the durability of the grinding pad. Furthermore, it provides sufficient strength for operations such as removing the grinding pad from the mold during molding and attaching the grinding pad to the pressure plate of the grinding device. In addition, when the workpiece contacts the grinding pad and a load is applied, it is less likely that protruding abrasive grains will be pressed back into the base material. This further reduces the grinding speed, even when using fine abrasive grains. If the weight-average molecular weight of the hydrolyzable resin is 500,000 or lower, not only can moldability be further maintained, but the time until disintegration due to hydrolysis can also be further shortened. From the same perspective, the weight-average molecular weight of the hydrolyzable resin is preferably between 110,000 and 400,000.

[0042] The weight-average molecular weight of hydrolyzable resins can be determined by gel permeation chromatography (GPC). The determination conditions are as follows. (Measurement conditions) Device: Showa Denko Corporation "Shodex-104" Tube Column: Two HFIP-606M tubes are connected in series with one HFIP-G tube serving as a protective pre-column. Column temperature: 40℃ Solution: HFIP solution containing 5 mM sodium trifluoroacetate Flow rate: 0.6 mL / min Detector: RI (Differential Refractive Index) Detector Molecular weight correction: Five standard polymethyl methacrylates with different molecular weights

[0043] The content of hydrolyzable resin relative to the total mass of the abrasive layer is preferably 20% by mass to 98.5% by mass, more preferably 50% by mass to 94% by mass, and even more preferably 70% by mass to 89% by mass. If the content of hydrolyzable resin is 20% by mass or more, the strength of the abrasive layer containing abrasive particles is higher. If the content of hydrolyzable resin is 98.5% by mass or less, the proportion of abrasive particles will not be too low, and therefore the grinding speed will not be too low. If the content of hydrolyzable resin is within the above range, while suppressing excessive disintegration of the abrasive layer, a more stable grinding speed can be easily obtained through the dressing effect. [ ] [1-1-2.] [Abrasive grains]

[0044] There are no particular limitations on the material of the abrasive grains. Examples include: diamond, silicon carbide, boron carbide, boron nitride, silicon nitride, cerium oxide, aluminum oxide, zirconium oxide, silicon oxide, iron oxide, manganese oxide, magnesium oxide, calcium oxide, barium oxide, zinc oxide, titanium oxide, chromium oxide, barium carbonate, and calcium carbonate. Among these, from the viewpoint of further improving the grinding speed, diamond, boron carbide, and boron nitride are preferred. From the viewpoint of easily processing high-hardness substrates such as SiC substrates, diamond is even more preferred.

[0045] While the upper limit of the median abrasive grain size also depends on the required grinding degree, it is preferably less than 30 μm, more preferably less than 20 μm, further preferably less than 10 μm, especially preferably less than 5 μm, very preferably less than 3 μm, and most preferably less than 1 μm. The lower limit of the median abrasive grain size is not particularly limited as long as a grinding speed above the specified level can be achieved; it is preferably 0.05 μm or more, more preferably 0.1 μm or more, and further preferably 0.2 μm or more.

[0046] The median particle size of abrasive particles can be determined based on the particle size distribution measured by particle size analysis - laser diffraction scattering method (ISO 13320:2020). Specifically, a laser diffraction particle size analyzer (such as the Mastersizer 3000 from Malvern) can be used to measure particle size at a temperature of 21°C, with ion-exchanged water as the dispersion medium, a refractive index of 1.330, and the Mie theory as the light scattering model. Abrasive particles can be obtained by heating and melting the abrasive layer, then passing the resulting melt through a filter to separate the abrasive particles from the hydrolyzable resin.

[0047] There is no particular limitation on the content of abrasive particles, but it is preferably 1% to 55% by mass relative to the total mass of the grinding layer, and more preferably 5% to 40% by mass. If the above-mentioned content of abrasive particles is 1% by mass or more, the grinding speed can be further improved. If the above-mentioned content of abrasive particles is 55% by mass or less, the formability or machinability of the grinding pad can be further improved. Specifically, when the median particle size of the abrasive particles is less than 1 μm, the content of abrasive particles relative to the total mass of the grinding layer is preferably 5% to 15% by mass, and when the median particle size of the abrasive particles is 1 μm or more, the content of abrasive particles relative to the total mass of the grinding layer is preferably 9% to 30% by mass.

[0048] The content of abrasive particles can be determined using a thermogravimetric analysis (TGA) device. Specifically, on the surface of the abrasive layer of an unused abrasive pad, an arbitrary straight line passing through the center O of the abrasive layer is designated as line L, and a straight line perpendicular to line L and passing through the center O of the abrasive layer is designated as line M. The center O of the abrasive layer is then defined. Points located on line L and at the midpoint between the center O and the end of the abrasive layer are designated as a1 and a2, respectively. Points located on line M and at the midpoint between the center O and the end of the abrasive layer are designated as b1 and b2. At least 100 mg of test sample is taken from the abrasive layer within the range of each test point including O, a1, a2, b1, and b2, and appropriately pulverized to obtain the test sample from each test point. 20 mg ± 2 of the test sample is placed in a platinum flat-bottomed pan and heated from room temperature to 800°C at a rate of 10°C / min in air, and maintained at 800°C for 30 minutes to burn off components other than abrasive particles. The weight of the remaining sample is divided by the mass of the test sample to determine the abrasive particle content in the abrasive layer at each test point. In this case, the arithmetic mean of the abrasive content of each of the aforementioned five points is set as the representative value of the abrasive content of the grinding layer. [ ] [1-1-3.] [Other ingredients]

[0049] The abrasive layer may further contain other components besides hydrolyzable resin and abrasive particles. Examples of other components include resins other than hydrolyzable resin and hydrolysis accelerators. From the viewpoint of further improving the removal of decomposed hydrolyzable resin, the abrasive layer preferably contains a hydrolysis accelerator. A single hydrolysis accelerator may be used alone, or two or more may be used simultaneously.

[0050] Hydrolysis accelerators are compounds that promote the hydrolysis reaction of hydrolyzable resins. For example, they are preferably compounds that promote the penetration of the solution into the hydrolyzable resin by dissolving into the grinding fluid; more preferably, they are compounds that generate acids or bases in the presence of water. Examples of such decomposition accelerators include carboxylic anhydrides, phosphorus compounds, cyclic esters, and alkali metal oxides.

[0051] Examples of carboxylic anhydrides include hexanoic anhydride, octanoic anhydride, decanoic anhydride, lauric anhydride, myristic anhydride, palmitic anhydride, stearic anhydride, benzoic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, trimellitic anhydride, tetrahydrophthalic anhydride, butanetetracarboxylic anhydride, 3,3',4,4'-benzophenonetetracarboxylic anhydride, pyrocalcite dianhydride, diphenyltricarboxylic anhydride, biphenyltetracarboxylic anhydride, ethylene glycol bis(dehydrated trimellitic ester), and glyceryl bis(dehydrated trimellitic ester) monoacetate.

[0052] As a phosphorus compound, it is preferably an organophosphorus compound such as phosphate esters and phosphites, and more preferably an organophosphorus compound having at least one of the group consisting of a long-chain alkyl group selected from 8 to 24 carbon atoms, an aromatic ring, and a neopentyl tertrol skeleton.

[0053] Examples of phosphate esters having long-chain alkyl groups having 8 to 24 carbon atoms include mono- or di-stearyl acid phosphate esters or mixtures thereof, and di-2-ethylhexyl acid phosphate esters, etc. Examples of phosphites having an aromatic ring include tris(nonylphenyl) phosphite, etc. Examples of phosphites with a neopentyltetrayl backbone include cyclic neopentanetetrayl bis(2,6-di-tertiary butyl-4-methylphenyl) phosphite, cyclic neopentanetetrayl bis(2,4-di-tertiary butylphenyl) phosphite, and cyclic neopentanetetrayl bis(octadecyl) phosphite.

[0054] Examples of cyclic esters include glycolide, lactide, ε-caprolactone, γ-valerolactone, δ-valerolactone, diethanolamine, and glutaric anhydride.

[0055] Examples of alkaline metal oxides include magnesium oxide, zinc oxide, calcium oxide, sodium oxide, and copper oxide.

[0056] From the viewpoint that it exists relatively stably during molding and can further promote the hydrolysis of hydrolytic resin in the water-permeable grinding layer, carboxylic anhydride is preferred, more preferably phthalic anhydride, trimellitic anhydride, benzoic anhydride, 3,3',4,4'-benzophenone tetracarboxylic anhydride, pyrocalcite dianhydride, and especially preferably pyrocalcite dianhydride.

[0057] When the grinding layer contains a hydrolysis accelerator, the content of the hydrolysis accelerator relative to the total mass of the grinding layer is preferably 1% to 50% by mass, more preferably 3% to 15% by mass, and even more preferably 5% to 9% by mass. If the above-mentioned content of the hydrolysis accelerator is 1% by mass or more, it not only further promotes the decomposition of the hydrolyzable resin, but also easily forms an embrittled layer, thus further improving the removability of the decomposed hydrolyzable resin. If the above-mentioned content of the hydrolysis accelerator is 50% by mass or less, it not only makes it more difficult for the hydrolysis accelerator to exudate, but also further inhibits excessive spalling caused by excessive hydrolysis.

[0058] From the same perspective, the content of hydrolysis accelerator relative to the total mass of hydrolyzable resin is preferably 0.5% by mass or more and 45% by mass, more preferably 2% by mass or more and 14% by mass, and even more preferably 4% by mass or more and 8% by mass.

[0059] The content of hydrolysis accelerator in the grinding layer can be determined by gel permeation chromatography (GC). Specifically, similar to the determination of the content of abrasive particles, a sample is taken from the grinding layer, and the sample is dissolved in any solvent with p-chlorobenzophenone as an internal standard. The solution is then filtered and used as the test sample. When the hydrolyzable resin is a glycolic acid polymer, the aforementioned solvent is preferably DMSO (dimethyl sulfoxide). The GC assay conditions are shown below. Device: Shimadzu Corporation GC-2010 Carrier gas: Helium, Flow rate: 1.08 mL / min Column: RESTEK Rxi-5ms Column temperature: Hold at 150℃ for 5 minutes → (increase temperature at 20℃ / min) → Hold at 270℃ for 3 minutes Detector: FID (Flame Ionization Detector) Detector temperature: 300℃ Injection temperature: 180℃ GC determination calculates the content of hydrolysis accelerator in the grinding layer at each measurement point. In this case, the arithmetic mean of the hydrolysis accelerator content at the aforementioned measurement points is set as the representative value of the hydrolysis accelerator content in the grinding layer. [ ] [1-1-4.] [physical properties] (Tensile strength)

[0060] The tensile strength of the base material for the fixed abrasive grains at 25°C is not particularly limited, but it is preferably 55 MPa or higher. If the tensile modulus is 55 MPa or higher, when the workpiece is brought into contact with the abrasive pad and a load is applied, it is difficult for the abrasive grains protruding from the surface to be pressed back into the base material. From the same point of view, the tensile strength of the aforementioned base material is more preferably 60 MPa or higher. There is no particular upper limit to the tensile strength of the aforementioned base material; for example, it can be set to 1000 MPa or lower. The tensile strength can be measured according to ISO 527. (Tension Modulus)

[0061] The tensile modulus of the base material at 25°C is not particularly limited, but it is preferably 1 GPa or higher. If the tensile modulus is 1 GPa or higher, when the workpiece is brought into contact with the grinding pad and a load is applied, it is difficult for the abrasive grains protruding from the surface to be pressed back into the base material. This further reduces the decrease in grinding speed, even when using fine abrasive grains. Additionally, it reduces edge sinking of the workpiece after grinding (the phenomenon of concentrated grinding at the edges leading to a decrease in dimensional accuracy). From the same perspective, the tensile modulus of the base material is more preferably 3 GPa or higher, and more preferably 5 GPa or higher. There is no particular upper limit to the tensile modulus of the base material; for example, it can be set to 50 GPa or lower. The tensile modulus can be measured according to ISO 527.

[0062] The tensile strength and tensile modulus of the aforementioned base material can be adjusted by the type and content of the hydrolyzable resin, the type and content of the hydrolysis accelerator, the weight average molecular weight, and the cooling process during molding. For example, the lower the content of the hydrolysis accelerator, the easier it is to increase the tensile strength and tensile modulus. (density)

[0063] The density of the abrasive layer is not particularly limited, but it is preferably between 1.57 g / cm³ and 3.00 g / cm³, and more preferably between 1.60 g / cm³ and 2.00 g / cm³. The density of the abrasive layer can be determined according to JIS K 0061:2001 at 20°C and 65%RH. Furthermore, the test piece can be prepared in the same manner as the test piece for the pencil hardness test.

[0064] The density of the grinding layer can be adjusted by factors such as the content of abrasive grains. For example, the higher the content of abrasive grains, the greater the density of the grinding layer. (thickness)

[0065] There is no particular limitation on the thickness of the polishing layer, but for example, when used for processing substrates of semiconductor devices, it is preferably 0.1 mm to 30 mm, more preferably 0.3 mm to 10 mm, and even more preferably 0.5 mm to 5 mm. If the thickness of the polishing layer is 0.1 mm or more, the abrasive grains can be retained more adequately. [ ] [1-2.] [Other layers]

[0066] The polishing pad may consist of only a polishing layer, or it may further contain other layers. Examples of other layers include a substrate layer and an adhesive layer. The substrate layer may be, for example, a resin film. When the polishing pad includes a substrate layer, the polishing layer may be uniformly disposed on the substrate layer, or it may be disposed in a pattern. The adhesive layer may be an adhesive layer used to mount the polishing pad 100 onto the polishing pad (pressure plate 210 described later). [ ] [1-3.] [other]

[0067] Grooves can also be provided on the surface of the grinding layer. In this way, the grinding fluid can be easily distributed to the entire surface of the grinding layer through the grooves, and the chips (decomposed hydrolyzed resin, the workpiece, etc.) generated by the hydrolysis of the hydrolyzed resin can be easily discharged to the outside through the grooves.

[0068] The grooves can be configured to allow for the supply and discharge of grinding fluid and the removal of shavings from the hydrolyzed resin produced by hydrolysis. The top view of the grooves can be annular, radial, grid-like, or linear. In addition, the raised parts of the concave-convex pattern formed by the grooves can also be arranged in an island-like configuration. [ ] [2.] [Manufacturing Method of Abrasive Pads]

[0069] The abrasive pad of this embodiment can be manufactured using any method. For example, the abrasive pad can be manufactured by a process of 1) obtaining a composition containing hydrolyzable resin and abrasive particles and 2) molding the obtained composition to form an abrasive layer. 1) Procedure

[0070] The composition containing hydrolyzable resin and abrasive particles can be obtained by any method. For example, the above composition can be obtained by mixing hydrolyzable resin and abrasive particles. As a mixing machine, for example, rollers, kneaders, Bamboo mixers, extruders (single-shaft, multi-shaft), etc. can be used.

[0071] From the perspective of improving processability, mixing is preferably carried out under heating. The heating temperature can be set, for example, between 150°C and 270°C. In particular, when the above-mentioned components contain a hydrolysis accelerator, the heating temperature is preferably a temperature at which the hydrolysis accelerator can be dispersed in a stable state.

[0072] The form of the obtained components is not particularly limited; for example, they can be granular, powdery, or fibrous. 2) Procedure

[0073] The obtained components are then molded into a specified shape. There are no particular limitations on the molding method; for example, it can be any of injection molding, melt extrusion molding, solidification extrusion molding, vacuum forming, transfer molding, and compression molding. Alternatively, 3D printing can also be used for molding.

[0074] In the compression molding process, the particles of the above-mentioned components are supplied into a mold. Then, the mold temperature is set to 150°C to 270°C, and pressure molding is performed to obtain an abrasive pad containing the molded material. In addition, by performing the compression molding process in a drying chamber with a dew point temperature of -40°C (under dry conditions), the hydrolysis of the resin can be prevented, and the strength of the pad can be maintained.

[0075] Grooves can also be formed on the surface of the molded body of the above-mentioned components. There are no particular limitations on the method of forming the grooves; they can be formed by machining the surface of the molded body of the above-mentioned components, or by molding the above-mentioned components using a mold or casting mold with a pattern corresponding to the grooves. Furthermore, from the viewpoint of improving the dimensional stability of the molded product, annealing can be performed as needed. [ ] [3.] [Grinding Method for the Object Being Grinded]

[0076] Figure 1 is a schematic diagram showing a polishing apparatus 100 using the polishing pad of this embodiment. Detailed illustration of the polishing pad 110 is omitted in this figure.

[0077] As shown in Figure 1, the grinding apparatus 100 includes a grinding pad 110, a disc-shaped pressure plate 120 supporting the grinding pad 110, a disc-shaped grinding head 130 holding the workpiece 200, a carrier 140 holding the grinding head 130, a weight 150, and a supply nozzle 160 for supplying grinding fluid W. The pressure plate 120 can be rotated by a rotating shaft (not shown), and the grinding head 130 can be rotated by a rotating shaft 130A.

[0078] Furthermore, in this embodiment, while supplying the surface of the grinding pad 110 with the grinding fluid W containing water, the grinding pad 110 is made to slide relative to the workpiece 200 to grind the workpiece 200.

[0079] Specifically, first, a polishing pad 110 is mounted on the pressure plate 120. Then, the workpiece 200 held by the polishing head 130 is pressed against the polishing surface of the polishing pad 110, and while polishing fluid W is supplied from the supply nozzle 160, the pressure plate 120 and / or the polishing head 130 are rotated. In this way, the polishing pad 110 and the workpiece 200 slide relative to each other to polish the machined surface (polished surface) of the workpiece 200.

[0080] The material of the workpiece 200 is not particularly limited and can be ceramic, glass, etc. Examples of ceramic materials include Si (silicon), SiC (silicon carbide), GaN (silicon nitride), GaAs (gallium arsenide), sapphire, etc., with SiC and GaN being preferred. Specifically, the workpiece 200 can be made of materials used in semiconductor devices, electronic components, etc., especially Si substrates, SiC substrates, GaAs substrates, glass, hard disks, and LCD (liquid crystal display) substrates. Among these, semiconductor wafers are preferred, SiC substrates, sapphire substrates, or GaN substrates used in power devices are more preferred, and SiC substrates or GaN substrates are even more preferred.

[0081] The polishing slurry W contains at least water. When the polishing pad 110 contains glycolic acid polymer as a hydrolyzable resin, from the viewpoint of promoting the hydrolysis of glycolic acid polymer and further improving the finishing effect, the polishing slurry W is preferably an alkaline or acidic aqueous solution. In an alkaline aqueous solution, the carboxylic acid termini produced by hydrolysis remain in the form of carboxylate ions, thereby making it easier for the oligomers of the polymer produced by hydrolysis to dissolve into the liquid, thus promoting hydrolysis.

[0082] Alkaline aqueous solutions contain water and alkaline substances. Examples of alkaline substances include alkali metal hydroxides such as sodium hydroxide (NaOH) and potassium hydroxide (KOH), and organic bases such as tetramethylammonium hydroxide. From the viewpoint of further promoting the hydrolysis of glycolic acid polymers, the pH value of the alkaline aqueous solution is preferably 9 or higher, more preferably 12 or higher, and even more preferably 13 or higher. The upper limit of pH can be set, for example, to 14. The pH value is measured by a pH meter at 20°C according to JIS Z 8802:2011. The pH value of the alkaline aqueous solution can be adjusted by the amount of alkaline substance.

[0083] There are no particular restrictions on the temperature of the polishing slurry W; it can be set to between 1°C and 60°C.

[0084] The grinding fluid W may further contain other components besides those mentioned above, such as hydrolysis accelerators. Example

[0085] The present invention will be described below with reference to embodiments. The scope of the present invention is not to be limited by the embodiments. 1. Materials 1-1. Hydrolyzable resin

[0086] • PGA (a homopolymer of glycolic acid, weight average molecular weight 298,000, tensile strength 112.8 MPa) PLA (Natureworks 7000D, polylactic acid, weight average molecular weight 246,000)

[0087] The weight-average molecular weight and tensile strength of the above-mentioned PGA were determined using the following method. (Determination of weight-average molecular weight)

[0088] The weight-average molecular weight was determined by gel permeation chromatography (GPC). The determination conditions are as follows. Device: Showa Denko Co., Ltd. "Shodex-104" Tube Column: Two HFIP-606M tubes are connected in series with one HFIP-G tube serving as a protective pre-column. Column temperature: 40℃ Solution: HFIP solution containing 5 mM sodium trifluoroacetate Flow rate: 0.6 mL / min Detector: RI (Differential Refractive Index) Detector Molecular weight correction: Five standard polymethyl methacrylates with different molecular weights (Determination of tensile strength)

[0089] The tensile strength of the above-mentioned PGA was determined according to ISO 527. 1-2. Abrasive particles

[0090] Abrasive grain 1: Single-crystal diamond powder FRM (manufactured by Global Diamond, median particle size 0.25μm, amorphous) Abrasive particles 2: Single-crystal diamond powder FRM (manufactured by Global Diamond, median particle size 1.0μm, amorphous) Abrasive grain 3: Single-crystal diamond powder FRM (manufactured by Global Diamond, median particle size 3.0μm, amorphous) (Method for determining median particle size)

[0091] The median particle size of the abrasive particles was determined using the following method. Specifically, the particle size distribution was performed using a Mastersizer 3000 (Malvern) laser diffraction particle size analyzer at a measurement temperature of 21°C, with ion-exchanged water as the dispersion medium, a refractive index of 1.330, a Mie theory-based light scattering model, and a particle absorptivity of 0.100 and a refractive index of 2.418 for the polycrystalline diamond powder. The amount of abrasive particles added to the dispersion medium was adjusted to maintain a laser scattering intensity between 4% and 10%. 1-3. Hydrolysis accelerators

[0092] • Pyrocalcite dianhydride (PMDA) • Glycolide (GL) 2. Fabrication and Evaluation of Grinding Pads 2-1. Fabrication of Grinding Pads 1 to 9 (Mixed training program)

[0093] The ingredients shown in Table 1 were weighed according to the proportions shown in Table 1, and then mixed using a closed-type mixer (manufactured by Toyo Seiki Co., Ltd.) to obtain the composition. The mixing was carried out at the specified heater temperature, preheating time of 1 minute, mixing time of 5 minutes, and rotation speed of 50 rpm. In addition, the heater temperature was set to 250°C. (Molding process)

[0094] A SUS mold with a 150 mm diameter hole is prepared. The aforementioned mixed components are placed in the SUS mold and pressurized to form an abrasive pad consisting of a 2.0 mm thick disc-shaped abrasive layer. The temperature of the press is set to the same temperature as the heater temperature of the aforementioned closed-type mixer. After the pad is made, a grid-like groove is formed on the surface of the pad using a triangular cutter. 2-2. Assessment

[0095] For each of the obtained abrasive pads, the density, pencil hardness, and abrasive speed were determined using the following methods. 2-2-1. Density

[0096] The density of the grinding layer was determined at 20°C and 65%RH according to the specific gravity bottle method described in JIS K 0061:2001. 2-2-2. Pencil Hardness (1) Production of test pieces

[0097] Following the same molding procedure as described above, a polishing pad consisting of a 3.0 mm thick disc-shaped polishing layer is fabricated. The center of this polishing pad is designated as O, and the distance (radius) from center O to the end of the polishing pad (polishing layer) is defined as 1. Next, a circle with a radius of 0.6 is drawn with center O as the center. Two points on this circumference are positioned at the points that bisect the circumference, and two 10 mm × 10 mm × 3 mm rectangular test pieces are cut out centered at each point as test pieces for pencil hardness. Furthermore, to facilitate observation of scratches, portions of the polishing pad without groove processing are cut out. (2) Pencil hardness test

[0098] To prevent the test piece from moving, double-sided tape was applied to the back of the test piece and it was fixed to the base. Then, using a pencil hardness tester 054-1 (manufactured by Allgood), a pencil hardness test was performed on the test piece before and after immersion in ion-exchange water at 80°C for 3 hours. Specifically, a pencil hardness test (pencil hardness test before immersion) was conducted on the largest surface of one of the two prepared test pieces at 25°C and 60%RH. Next, for the other of the two prepared test pieces, after immersing it in ion-exchange water at 80°C for 3 hours, the test piece was dried in a drying chamber at a dew point temperature of -40°C for 1 hour. Then, a pencil hardness test (pencil hardness test after immersion) was performed on the surface of the dried test piece in the same manner as above.

[0099] In addition, except for the following points, the pencil hardness test is generally conducted in accordance with JIS K 5600-5-4:1999. • Because the test piece has thickness, a plate-shaped component of similar thickness is laid under the testing machine and fixed with double-sided tape so that the pencil lead is at the same height as the test piece. • The observation position of the scratch is set as the starting position of the test. • To ensure that the scratches are clearly visible and easy to observe, the pencil hardness test was conducted after setting the pencil and letting it stand for 2 minutes. • After the test, remove the pencil lead powder with an eraser to a degree that will not cause scratches or other damage to the surface. In addition, the pencil hardness test was conducted with a hardness limit of 6H. (3) Determining the hardness of a pencil

[0100] For both the test pieces before and after immersion, visually observe the scratches left after the pencil hardness test to determine the pencil hardness. The observation position of the scratches is set as the starting position of the test. Then, calculate the difference in pencil hardness before and after immersion (h0-h1). (4) Observation of scratches on the test pieces after immersion

[0101] For the impregnated test pieces, a pencil hardness test was conducted using a pencil with a hardness one grade higher than that of the impregnated test piece (the lowest pencil hardness required to produce a scratch). The scratches after the pencil hardness test were then observed using a laser microscope. The test was performed twice.

[0102] Specifically, proceed in the following order. 1) The field of view was divided into two equal parts, with the lower half including the scratch at the start of the experiment. Observation was performed using a laser microscope (Keyence VK-X260) at 20x magnification with an objective lens (Nikon) of NA=0.46. The width of the field of view was set to approximately 700 μm. Subsequently, a reference plane was established by estimating the plane across the entire field of view using the least squares method. Image processing was performed using a multi-file analysis application (Keyence VK-H1XM). 2) Next, taking the deepest point of the scratch at the start of the test as the origin O, the straight line passing through the origin O and perpendicular to the direction of the pencil hardness test as the x-axis, and the straight line passing through the origin O and perpendicular to the x-axis as the y-axis, the absolute value of the height from the origin O to the reference plane is set as D. Furthermore, the highest point within the area encompassing the scratch observation region (approximately 100 μm wide in the direction of pencil travel) and the region extending approximately 200 μm from the origin O to the y-axis in the direction of pencil travel is set as point A, and the absolute value of the height from the reference plane to point A is set as H. Then, H / D is calculated. 2-2-3. Grinding speed (1) Pretreatment of grinding pad

[0103] Since the abrasive grains are embedded in the resin after molding, the polishing pad is dressed for 10 minutes with a pressure of 10.8 kPa using a #1000 diamond dresser (Fujiwara Sangyo Co., Ltd. double-sided diamond grinding stone, round) before a polishing test is conducted. (2) Pre-processing of the workpiece being ground

[0104] The lapping process is performed by using a slurry containing polycrystalline diamonds with a median particle size of 9 μm to coarsely grind the surface of a 20 × 20 mm square SiC substrate, which is the object to be lapped. (3) Grinding test

[0105] As shown in Figure 1, the grinding test is conducted by mounting a grinding pad on the grinding apparatus 100. Specifically, a double-sided adhesive film (e.g., AS ONE OCA50-A4) is used to mount the grinding pad onto the pressure plate 120 (grinding plate). The double-sided adhesive film is applied to the grinding pad and grinding plate using a rubber roller or similar device in a manner that avoids introducing air bubbles.

[0106] Then, the SiC substrate (20×20 mm square) that has undergone the above-mentioned pre-processing is pressed against the rotating polishing pad as the polishing object 200 for polishing. The polishing conditions are as follows. At this time, a load of jig (polishing head 130) and weight 150 is applied to the substrate. (Grinding conditions) Grinding device: Dia-Lap ML-150P (manufactured by Maruto) Grinding disc rotation speed: 100 rpm Grinding disc diameter: 150 mm Forced driving and shaking of the workpiece being ground: None Surface pressure: 250gf / cm2 Flow rate of grinding slurry: 75 mL / h Grinding slurry: NaOH aqueous solution with pH=13 (20℃)

[0107] Then, the grinding speed was determined using the following method. The thickness of the workpiece to be ground is measured using an electric micrometer Millimar 1240 (manufactured by Mahr) while the workpiece is attached to the fixture. The thickness of the workpiece was measured at five locations and the average value was taken. The grinding speed was calculated based on the grinding time (min) and the thickness reduction (removal amount, μm).

[0108] The evaluation results of abrasive pads 1 to 9 are shown in Table 1. In addition, regarding the test piece before impregnation of the abrasive pad 1 (Example) and after immersion in ion-exchange water at 80°C for 3 hours, the laser microscope images of the test piece surface after pencil hardness tests at various hardness levels are shown in Figure 2. In addition, regarding the test pieces of the abrasive pad 7 (comparative example) before impregnation and after being immersed in ion-exchange water at 80°C for 3 hours, the laser microscope images of the test piece surface after the pencil hardness test at various hardness levels are shown in Figure 3.

[0109] [Table 1] Grinding pad number 1 2 3 4 5 6 7 8 9 Composition of the grinding layer Hydrolyzable resin type PGA PGA PGA PGA PGA PGA PLA PLA PGA Content (wt%)* 84.7 66.7 84.7 84.7 84.7 92.6 90.0 84.7 38.9 abrasive grains type Abrasive 1 Abrasive 1 Abrasive 2 Abrasive 3 Abrasive 1 Abrasive 2 Abrasive 1 Abrasive 1 Abrasive 1 Median particle size (μm) 0.25 0.25 1.0 3.0 0.25 1.0 0.25 0.25 1.0 Content (wt%)* 9.41 28.6 9.41 9.41 9.41 0.9 10.0 9.41 58.4 Decomposition Accelerator type PMDA PMDA PMDA PMDA GL PMDA - PMDA PMDA Content (wt%)* 5.9 4.7 5.9 5.9 5.9 6.5 - 5.9 2.7 Physical properties of the grinding layer thickness mm 2 2 2 2 2 2 2 2 - density g / cm3 1.66 1.88 1.66 1.66 1.66 1.58 1.36 1.36 - Evaluate Pencil hardness Before soaking 6H 6H 6H 6H 6H 6H 2H H - After soaking B F 2B 3B 3H 3B 2H HB - Hardness difference Δ 8 6 9 10 3 10 0 2 - Types of scratches Cohesion and Destruction Cohesion and Destruction Cohesion and Destruction Cohesion and Destruction Cohesion and Destruction Cohesion and Destruction Plastic deformation Cohesion and Destruction - H / D 0.18 0.47 0.39 0.45 0.38 0.14 1.1 0.47 - Grinding speed (μm / h) 60min 0.88 0.54 3.0 6.6 1.6 0.34 0.08 0.44 - 90min 1.2 0.48 3.6 6.6 1.0 0.24 0.00 0.18 - 120min 1.06 0.62 2.8 7.2 0.84 0.28 0.02 0.00 - *Containment rate relative to 100% by mass of the abrasive layer (1) Regarding the pencil hardness test

[0110] Before impregnation, the abrasive pad 1 (Example) does not produce scratches below 6H (see left side of Figure 2), indicating that the pencil hardness before impregnation is 6H. On the other hand, after impregnation, it does not produce scratches below B, but scratches do occur above HB (see right side of Figure 2), indicating that the pencil hardness after impregnation is B. Furthermore, the scratches after impregnation are all cohesive damage.

[0111] In contrast, the abrasive pad 7 (comparative example) did not produce scratches on pencils with a hardness below 2H before and after impregnation, but scratches appeared on pencils with a hardness above 3H (see Figure 3). This indicates that the pencil hardness remained unchanged at 2H before and after impregnation. Furthermore, the scratches after impregnation were all plastic deformations. Additionally, the area enclosed by the white line in Figure 3 represents the plastic deformation portion. (2) Regarding the grinding test

[0112] As shown in Table 1, it can be seen that grinding pads 1 to 6, with a pencil hardness difference of 3 or more between the grinding layers before and after impregnation, can maintain the grinding speed well. In contrast, the grinding pads 7 and 8, whose pencil hardness difference between the grinding layers before and after impregnation was less than 3, showed a significant decrease in grinding speed after 120 minutes, indicating that they could not maintain the grinding speed. While it also depends on the median abrasive grain size, it can be observed, for example, that the side with a lower abrasive grain content exhibits a greater difference in hardness before and after impregnation, and a smaller decrease in grinding speed (comparison of grinding pads 1 and 2). Although it also depends on the abrasive grain size, it is believed that the side with a lower abrasive grain content will have higher grinding pressure.

[0113] Therefore, it can be seen that in abrasive pads where the difference in pencil hardness between the abrasive layers before and after impregnation is 3 or more, the decomposed PGA becomes an embrittled layer and is effectively removed, thereby maintaining the abrasive speed effectively.

[0114] This application claims priority based on Japanese Patent Application No. 2024-193663, filed November 5, 2024. The entire contents of the description and drawings of that application are incorporated herein by reference. Industrial utilization

[0115] According to the present invention, a grinding pad that easily removes the decomposed adhesive resin and has a small decrease in grinding speed, and a grinding method for grinding objects using the same pad, are provided.

[0116] 100: Grinding device; grinding pad 110: Grinding pad 120: Pressure plate 130: Grinding head 130A: Rotary shaft 140: Carrier 150: Heavy objects 160: Supply nozzle 200: Grinding material 210: Pressure plate W: Grinding fluid

Claims

1. An abrasive pad comprising an abrasive layer containing a hydrolyzable resin and abrasive particles, wherein after being immersed in ion-exchange water at 80°C for 3 hours, the pencil hardness of the abrasive layer at 25°C and 60%RH is lower than that of the abrasive layer at 25°C and 60%RH before immersion, and the difference in pencil hardness of the abrasive layer at 25°C and 60%RH before and after immersion is 3 levels or more.

2. The abrasive pad as requested in claim 1, wherein the abrasive layer prior to impregnation has a pencil hardness of 2H or higher at 25°C and 60%RH.

3. The abrasive pad as claimed in claim 2, wherein the scratches produced during a pencil hardness test using a pencil with a higher hardness than that of the aforementioned abrasive layer after immersion in ion-exchange water at 80°C for 3 hours are considered cohesive damage.

4. The abrasive pad as requested in item 1, wherein the median particle size of the aforementioned abrasive grains is less than 30 μm.

5. The abrasive pad of claim 1, wherein the content of the aforementioned abrasive grains in the aforementioned abrasive layer is more than 1% by mass and less than 55% by mass relative to the total mass of the aforementioned abrasive layer.

6. The abrasive pad of claim 1, wherein the content of the aforementioned hydrolyzable resin in the aforementioned abrasive layer is more than 20% by mass and less than 98.5% by mass relative to the total mass of the aforementioned abrasive layer.

7. The abrasive pad as claimed in claim 1, wherein the aforementioned hydrolyzable resin is mainly composed of glycolic acid polymer.

8. The abrasive pad of claim 1, wherein the aforementioned abrasive layer further contains a hydrolysis accelerator.

9. The abrasive pad of claim 8, wherein the aforementioned hydrolysis accelerator comprises at least one selected from the group consisting of carboxylic anhydrides, phosphorus compounds, cyclic esters and basic metal oxides.

10. The abrasive pad of claim 1, wherein the thickness of the aforementioned abrasive layer is more than 0.1 mm and less than 30 mm.

11. The abrasive pad of claim 1, wherein the density of the aforementioned abrasive layer is more than 1.57 g / cm3 and less than 3.00 g / cm3.

12. A grinding method for a workpiece, comprising the following steps: while supplying an abrasive liquid containing water to the surface of the abrasive layer of an abrasive pad as claimed in any of claims 1 to 11, the abrasive pad is slid relative to the workpiece to grind the workpiece.

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