Porous resin body, compound semiconductor polishing pad, and method for manufacturing porous resin body

Abstract

A method for producing a resin porous body having fine pores is provided. [Solution] The method for producing a resin porous body includes a melt preparation step P1 in which a base resin having high resistance to oxidizing agents and abrasion and a disaccharide such as lactose are melted in an organic solvent to obtain a melt, a forming step P2 in which the melt is formed into a thin plate to obtain a thin plate-like molded body, a precipitation step P3 in which the thin plate-like molded body is left in cold water to finely precipitate a solid of the disaccharide in the thin plate-like molded body, a substitution step P4 in which the thin plate-like molded body that has been subjected to the precipitation step P3 is left in hot water to substitute the solid of the disaccharide with water, and a drying step P5 in which the thin plate-like molded body is dried until all moisture is removed. The resin porous body is made of a base resin having high resistance to strong oxidizing agents, and fine pores are formed in the base resin, so that when a hard-to-polish wafer is polished using a polishing pad 18, there are no scratches, and the polishing rate PR and surface roughness Sa can be maintained for a long time.

Description

[Technical field]

[0001] The present invention relates to a method for producing a porous resin body having high chemical resistance and fine pores, and to a compound semiconductor polishing pad using the porous resin body. [Background technology]

[0002] There is a demand for resin porous bodies that are highly chemical-resistant and have fine pores for use in compound semiconductor polishing pads for polishing compound semiconductor wafers, water-adhesive pads for fixing compound semiconductor wafers on polishing disks, synthetic leather, vibration-proof sheets, sound-absorbing materials, water-absorbing and water-retaining bodies, separators and separation membranes for fuel cells, and the like.

[0003] For example, semiconductor wafers such as SiC wafers, GaN wafers, Si wafers, and Si oxide wafers are known to be difficult to polish. A polishing method based on the CMP method has been proposed for polishing such semiconductor wafers using a resin polishing pad that mechanically promotes polishing and a polishing solution that chemically promotes polishing. For example, the polishing method described in Patent Document 1 is one such method. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-057368 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the hard-to-polish wafer is polished on a polishing pad using a polishing solution containing a strong oxidizing agent such as potassium permanganate, if the resin constituting the polishing pad is a resin with low resistance to the oxidizing agent, such as a foamed polyurethane resin, the resin deteriorates, and the surface roughness and shape of the polishing material are easily deteriorated, resulting in a short service life of the polishing pad. On the other hand, when a polishing pad with a high proportion of polyurethane resin in the polishing pad and fewer pores is used, the service life is longer, but there is a problem that scratches are easily caused due to the small number of pores.

[0006] The present invention has been made against the background of the above circumstances, and an object of the present invention is to provide a method for producing a resin porous body which, when used in a compound semiconductor polishing pad, produces a resin porous body which is free of scratches when polishing a difficult-to-polish wafer and can maintain the polishing rate and surface roughness for a long period of time, and a compound semiconductor polishing pad using the resin porous body.

[0007] The present inventors have conducted various studies in light of the above circumstances, and as a result, have found that PES (polyethersulfone) resin or PVDF-HFP resin (solid) which is highly resistant to permanganate-based strong oxidizing agents and lactose (solid), which is a disaccharide, are dissolved in a normal water-soluble solvent such as N-methyl-2-pyrrolidone under warm conditions, and the melt obtained by dissolving is molded into a predetermined shape. When the molded body is placed in cold water, lactose precipitates as a fine solid in the melt, and when the precipitated solid and the solvent are replaced with water, a resin porous body having fine pores with an average diameter of about 0.2 to 3 μm is obtained. The inventors have found that when polishing is performed with a polishing pad using the resin porous body, there are no scratches, and the polishing rate and surface roughness can be maintained for a long time. The present invention is based on this finding. [Means for solving the problem]

[0010] No. 1 The gist of the invention is (1) a method for producing a resin porous body having high resistance to oxidizing agents and abrasion and having fine pores, comprising: (2) PES (polyethersulfone) resin or PVDF-HFP (copolymer of 80% polyvinylidene fluoride and 20% hexafluoropropylene) resinThe method includes the steps of: (1) melt preparation step of melting a base resin and a disaccharide in an organic solvent to obtain a melt; (2) molding step of molding the melt into a thin plate to obtain a thin plate-like molded body; (3) precipitation step of leaving the thin plate-like molded body in cold water whose temperature is lower than the melting point of the disaccharide to finely precipitate a solid of the disaccharide in the thin plate-like molded body; (4) replacement step of leaving the thin plate-like molded body that has been subjected to the precipitation step in warm water whose temperature is higher than the cold water to replace the finely precipitated solid of the disaccharide in the thin plate-like molded body and the organic solvent in the thin plate-like molded body with water; and (5) drying step of drying the thin plate-like molded body until no moisture remains in the thin plate-like molded body.

[0012] No. 2 The gist of the invention is as follows: 1 In the present invention, the organic solvent is N-methyl-2-pyrrolidone or 2-pyrrolidone. If room temperature is defined as 10°C to 30°C, N-methyl-2-pyrrolidone has a melting point below freezing (-24°C), and 2-pyrrolidone has a melting point at room temperature (24.6°C).

[0013] No. 3 The gist of the invention is as follows: 1 In the present invention, the organic solvent is a solvent that disperses in water and dissolves the PES (polyethersulfone) resin and the PVDF-HFP (a copolymer of 80% polyvinylidene fluoride and 20% propylene hexafluoride) resin.

[0014] No. 4 The gist of the invention is as follows: 1 In the present invention, the precipitation step involves leaving the thin plate-shaped body in the cold water at 5 to 10°C, and the replacement step involves leaving the thin plate-shaped body that has undergone the precipitation step in the warm water at 40 to 60°C.

[0016] No. 5The gist of the invention is a composite material made of a base resin, which is a PES (polyethersulfone) resin or a PVDF-HFP (a copolymer of 80% polyvinylidene fluoride and 20% propylene hexafluoride) resin, and fine pores formed in the base resin. Have A compound semiconductor polishing pad is constructed of a resin porous body and used to polish difficult-to-polish compound semiconductor wafers using a polishing liquid containing a permanganate-based strong oxidizing agent, the compound semiconductor polishing pad having 48.4 to 85.2 volume % pores, 14.8 to 51.6 volume % of the base resin, and a durometer hardness (Type-D) of 12.5 to 58.1. Effect of the Invention

[0019] No. 1 In the method for producing a resin porous body having high oxidizing agent resistance and abrasion resistance and fine pores according to the present invention, PES (polyethersulfone) resin or PVDF-HFP (copolymer of 80% polyvinylidene fluoride and 20% hexafluoropropylene) resin The process includes a melt preparation step in which a base resin and a disaccharide (e.g., lactose) are melted in an organic solvent to obtain a melt, a molding step in which the melt is molded into a thin plate to obtain a thin plate-like molded body, a precipitation step in which the thin plate-like molded body is left in cold water whose temperature is lower than the melting point of the disaccharide to finely precipitate a solid of the disaccharide in the thin plate-like molded body, a substitution step in which the thin plate-like molded body that has been subjected to the precipitation step is left in hot water whose temperature is higher than the cold water to substitute the solid of the disaccharide finely precipitated in the thin plate-like molded body and the organic solvent in the thin plate-like molded body with water, and a drying step in which the thin plate-like molded body is dried until no moisture remains in the thin plate-like molded body. can The resin porous body is made of a base resin that is highly resistant to strong oxidizing agents, and fine pores are formed within the base resin, so there are no scratches when polishing difficult-to-polish wafers, and the polishing rate and surface roughness are improved. Sato can be maintained for a long time. In addition, since the resin porous body is made of PES (polyethersulfone) resin or PVDF-HFP (a copolymer of 80% polyvinylidene fluoride and 20% propylene hexafluoride) resin, a resin porous body having high resistance to oxidizing agents and abrasion is obtained.

[0021] No. 2. InventionIn the above, the organic solvent is N-methyl-2-pyrrolidone or 2-pyrrolidone. If room temperature is defined as 10°C to 30°C, N-methyl-2-pyrrolidone has a melting point below the freezing point, and 2-pyrrolidone has a melting point at room temperature. These organic solvents dissolve the base resins, PES (polyethersulfone) resin and PVDF-HFP (a copolymer of 80% polyvinylidene fluoride and 20% propylene hexafluoride), and lactose, and in the precipitation step, the thin plate-shaped molded body is left in cold water at a temperature lower than the melting point of lactose, so that the solid lactose can be finely precipitated in the thin plate-shaped molded body. In addition, when the organic solvent is 2-pyrrolidone, which has a melting point at room temperature, in the precipitation step, in addition to the fine precipitation of the solid lactose, the solid 2-pyrrolidone can also be precipitated.

[0022] No. 3 In the present invention, the organic solvent is a solvent that disperses in water and dissolves PES (polyethersulfone) resin and PVDF-HFP (copolymer of 80% polyvinylidene fluoride and 20% hexafluoropropylene) resin. This allows the thin plate-shaped body that has been subjected to the precipitation step to be left in hot water that is higher than the temperature of the cold water and the melting point of the organic solvent, so that the lactose solid finely precipitated in the thin plate-shaped body and the organic solvent in the thin plate-shaped body can be replaced with water.

[0023] No. 4 In the present invention, the precipitation step involves leaving the thin plate-like molded body in cold water at 5 to 10° C., and the replacement step involves leaving the thin plate-like molded body that has been subjected to the precipitation step in warm water at 40 to 60° C. As a result, after lactose solids are finely precipitated in the thin plate-like molded body in the precipitation step, the lactose solids precipitated in the thin plate-like molded body and the organic solvent in the thin plate-like molded body are replaced with water in the warm water.

[0025] No. 5 In the present invention, a base resin, which is a PES (polyethersulfone) resin or a PVDF-HFP (a copolymer of 80% polyvinylidene fluoride and 20% propylene hexafluoride) resin, and fine pores formed in the base resin are HaveThis compound semiconductor polishing pad is composed of a resin porous body and is used to polish difficult-to-polish compound semiconductor wafers using a polishing liquid containing a permanganate-based strong oxidizing agent. The compound semiconductor polishing pad has 48.4 to 85.2 volume % of pores, 14.8 to 51.6 volume % of the base resin, and a durometer hardness (Type-D) of 12.5 to 58.1, and is therefore free from scratches and can maintain the polishing rate and surface roughness for a long period of time. [Brief description of the drawings]

[0026] [Figure 1] 1 is a perspective view showing a schematic diagram of a surface polishing apparatus used for polishing by a CMP method in which a polishing pad according to an embodiment of the present invention is used. [Diagram 2] 2 is a plan view for explaining a rotation mechanism of an application disk of the surface polishing apparatus of FIG. 1. FIG. [Diagram 3] 2 is a process diagram illustrating a manufacturing process for manufacturing a resin porous body constituting the polishing pad of FIG. 1. [Figure 4] FIG. 2 is a diagram showing the chemical structure of a PES resin (polyethersulfone resin), which is an example of a resin constituting the polishing pad of FIG. [Diagram 5] FIG. 2 is a diagram showing the chemical structure of PVDF-HFP resin (polyvinylidene fluoride 80% + hexafluoropropylene 20% copolymer resin), which is another example of the resin constituting the polishing pad of FIG. [Figure 6] 1 is a table showing samples used in polishing test 1 and the results of the polishing test. [Figure 7] 1 is a table showing the PES resin ratio, pore ratio, and durometer hardness of Examples 5 to 6 and 9 in the samples used in Polishing Test 1. [Figure 8] 1 is a table showing the PVDF-HFP resin ratio, pore ratio, and durometer hardness of Example Products 7 and 8 in the samples used in Polishing Test 1. [Figure 9] FIG. 2 is a 500x SEM photograph of a cross section of Example Product 6 in the sample used in Polishing Test 1 to show pores in Example Product 6. [Figure 10]FIG. 2 is a 10,000x SEM photograph of a cross section of Example Product 6 in the sample used in Polishing Test 1 to show pores in Example Product 6. [Figure 11] FIG. 13 is a 500x SEM photograph of a cross section of Example Product 9 in the sample used in Polishing Test 1 to show pores in Example Product 9. [Figure 12] FIG. 2 is a 10,000x SEM photograph of a cross section of Example Product 9 in the sample used in Polishing Test 1 to show pores in Example Product 9. [Figure 13] FIG. 2 is a 500x SEM photograph of a cross section of Comparative Example 1 in a sample used in Polishing Test 1 to show pores in Comparative Example 1. [Figure 14] FIG. 2 is a 500x SEM photograph of a cross section of Comparative Example 2 in the sample used in Polishing Test 1 to show pores in Comparative Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] An embodiment of the present invention will now be described with reference to the drawings. Note that in the following embodiment, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. EXAMPLES

[0028] Fig. 1 is a schematic diagram of a main part of a surface polishing apparatus 10 for polishing hard-to-polish compound semiconductor wafers such as SiC wafers, GaN wafers, and InP wafers, with the guide roller fixing table removed, according to an example of the present invention. In Fig. 1, the surface polishing apparatus 10 is provided with a circular polishing platen (rotary table) 12 supported so as to be rotatable about its vertical rotation axis C1, and the polishing platen 12 is rotated at a constant speed in one rotation direction indicated by an arrow in the figure by a platen driving motor 14. A compound semiconductor polishing pad (hereinafter referred to as polishing pad) 18 made of a sheet-like resin porous body 17 is attached to the upper surface of the polishing platen 12, i.e., the surface against which a workpiece (hard-to-polish compound semiconductor wafer) 16 is pressed.

[0029] The workpiece 16 is held on the lower surface of the application disc 20, i.e., the surface facing the polishing pad 18, and the application disc 20 presses the workpiece 16 against the polishing pad 18 with a predetermined load. A drip nozzle 22 is provided near the application disc 20 of the surface polishing device 10, and a strongly acidic polishing solution PF containing a strong oxidizing agent of permanganate such as potassium permanganate (KMnO4) added thereto is supplied onto the polishing table 12 from a tank (not shown).

[0030] The surface polishing apparatus 10 is provided, as required, with an adjustment tool holding member (not shown) that is arranged rotatable about the rotation axis C1 of the polishing table 12 and movable in the direction of the rotation axis C1 and in the radial direction of the polishing table 12, and an abrasive body adjustment tool (dresser or conditioner) such as a diamond wheel (not shown) that is attached to the lower surface of the adjustment tool holding member, i.e., the surface facing the polishing pad 18. The adjustment tool holding member and the abrasive body adjustment tool attached thereto are pressed against the polishing pad 18 while being rotated and driven by an adjustment tool drive motor (not shown), and are moved back and forth in the radial direction of the polishing table 12, thereby adjusting the polishing surface of the polishing pad 18 and constantly maintaining the surface state of the polishing pad 18 in a state suitable for polishing.

[0031] 2, at a position eccentric from the rotation axis C1 on the polishing table 12, the outer peripheral surface of a short cylindrical attachment disk 20, which holds the workpiece 16 to be polished on its underside by suction, adhesion, or a holding frame, is received by a pair of rotatable guide rollers 30 and a drive guide roller 32 provided on a guide roller fixing base 28, which is fixed in a position and fixed to a frame (not shown), so that the attachment disk 20 can rotate about the rotation axis C2. The attachment disk 20 is rotated about the rotation axis C2 by a rotation force based on the difference in peripheral speed between the polishing table 12 or the polishing pad 18, and the attachment disk 20 is pressed against the polishing pad 18 on the polishing table 12 by the load of, for example, a weight 34, thereby polishing the workpiece 16.

[0032] The following polishing method is applied during polishing by the surface polishing device 10. That is, while the polishing pad 18 attached to the polishing table 12, the attachment disk 20, and the workpiece 16 held on its lower surface are rotated around the rotation axis C1 and the rotation axis C2 by the table drive motor 14 and the drive guide roller 32, the polishing liquid PF not containing abrasive grains is supplied from the drip nozzle 22 onto the surface of the polishing pad 18, while the workpiece 16 held on the attachment disk 20 is pressed against the polishing pad 18. As a result, the surface to be polished of the workpiece 16, i.e., the surface facing the polishing pad 18, is polished flat by the chemical polishing action of the polishing liquid PF.

[0033] The polishing pad 18 is composed of a resin porous body 17 including fine pores with an average diameter of 0.2 to 3 μm. The resin porous body 17 functions as a base resin of the polishing pad 18. The resin porous body 17 is made of PES (polyethersulfone) resin that does not contain abrasive grains, or PVDF-HFP resin (polyvinylidene fluoride 80% + hexafluoropropylene 20% copolymer resin) and is formed into a sheet shape with a thickness of about 2 to 3 mm. PES resin and PVDF-HFP resin have high resistance to the strong oxidizing agent of permanganate in the polishing liquid PF and abrasion resistance that can obtain a high polishing rate PR. The PES resin has the chemical structure shown in FIG. 4, and the PVDF-HFP resin has the chemical structure shown in FIG. 5.

[0034] The polishing pad 18 preferably has 48.4 to 85.2 volume % of pores, 14.8 to 51.6 volume % of base resin, and a durometer hardness (Type-D) of 12.5 to 58.1.

[0035] The resin porous body 17 constituting the polishing pad 18 is manufactured by the manufacturing steps P1 to P5 shown in Fig. 3. In Fig. 3, in the melt preparation step P1, PES resin or PVDF-HFP resin (solid at room temperature) and disaccharide, for example, lactose (C 12 H 22 O 11A melt is prepared by heating and stirring the lactose (which is solid at room temperature) together with a normal organic solvent having a freezing point below the freezing point, such as N-methyl-2-pyrrolidone, at a temperature of 50°C or higher. Next, in the molding step P2, the melt is molded into a thin plate of, for example, about 3 mm by slip casting or blade casting to obtain a thin plate-like molded body. Next, in the precipitation step P3, the thin plate-like molded body is left for about 5 hours in cold water at a temperature of, for example, 5 to 10°C, which is sufficiently lower than the melting point of lactose (202.8°C), to finely precipitate solid lactose in the thin plate-like molded body. The fine precipitates (crystals) of lactose form micropores in the PES resin after the drying step P5 described below. The size of the micropores is adjusted by the temperature of the cold water and the leaving time, but the average diameter is preferably 0.2 to 3 μm.

[0036] In the subsequent substitution step P4, the thin plate-shaped body that has been subjected to the precipitation step P3 is left in hot water, for example, at 40 to 60°C, which is higher than the temperature of the cold water and the melting point of 2-pyrrolidone, for about 5 hours, so that the solid lactose finely precipitated in the thin plate-shaped body and the organic solvent in the thin plate-shaped body are replaced with water, and the thin plate-shaped body is hardened. Then, in the drying step P5, the thin plate-shaped body is dried until all moisture is removed from the body. This produces a thin plate-shaped PES resin or PVDF-HFP resin porous resin body (base resin of polishing pad 18) 17 having micropores of about 0.2 to 3 μm.

[0037] N-methyl-2-pyrrolidone has the chemical formula CHNO, has a freezing point of -24°C and a boiling point of 202°C, is soluble in water, and is capable of dissolving the base resin (PES resin or PVDF-HFP resin). As described in the melt preparation step P1, the precipitation step P3, and the replacement step P4 above, an organic solvent other than N-methyl-2-pyrrolidone may be used as long as it can melt the PES resin, has a freezing point below the freezing point, and can be replaced with water at the temperature of hot water.

[0038] [Polishing test 1] Hereinafter, the inventors will explain the polishing test 1 for semiconductor wafers. In the polishing test 1, the comparative examples 1-2 and the examples 5-9 shown in FIG. 6 were applied to an apparatus configured similarly to the surface polishing apparatus 10 shown in FIG. 1, and a 4-inch diameter SiC wafer was polished under the test conditions of the polishing test 1 shown below. The examples 5-6 were produced using the manufacturing process shown in FIG. 3 by changing the ratio of N-methyl-2-pyrrolidone, lactose, and PES resin so that the ratio of pores (volume %) differs between the examples. The examples 7-8 were produced using the manufacturing process shown in FIG. 3 by changing the ratio of N-methyl-2-pyrrolidone, lactose, and PVDF-HFP resin so that the ratio of pores (volume %) differs between the examples. The example 9 was produced using the manufacturing process shown in FIG. 3 by changing the ratio of 2-pyrrolidone, lactose, and PES resin so that the ratio of pores (volume %) differs between the examples.

[0039] Fig. 7 shows the volume fraction of PES resin, the volume fraction of pores, and the durometer hardness (Type-D) of Examples 5 to 6 and 9. Fig. 8 shows the volume fraction of PVDF-HFP resin, the volume fraction of pores, and the durometer hardness (Type-D) of Examples 7 to 8.

[0040] 9 and 10 show SEM photographs of Example 6, which is representative of Examples 5 to 8, at 500 and 10,000 magnifications. From the SEM photograph of FIG. 10, fine pores of about 0.2 to 2 or 3 μm are observed. FIG. 11 and FIG. 12 show SEM photographs of Example 9 at 500 and 10,000 magnifications. From the SEM photograph of FIG. 12, homogeneous fine pores of about 0.2 to 3 μm are observed. In Example 9, 2-pyrrolidone having a melting point at room temperature (24.6° C.) is used as an organic solvent to dissolve the base resin, so in the precipitation step P3, a solid of 2-pyrrolidone is precipitated in addition to lactose, contributing to the formation of pores. Note that DMSO (dimethyl sulfoxide) having a melting point at room temperature (18.4° C.) may be used instead of the above 2-pyrrolidone.

[0041] Comparative Example 1 is made of a hard polyurethane resin in which pores of 20 to 40 μm are created using a pore-forming agent. FIG. 13 shows an SEM photograph of Comparative Example 1 at 500 times magnification. Pores of about 20 to 40 μm are observed in the SEM photograph of FIG. 13. Comparative Example 2 is a nonwoven fabric in which intertwined polyester fibers are bonded with polyurethane resin, and gaps of about 100 μm are formed between the fibers. FIG. 14 shows an SEM photograph of Comparative Example 2 at 500 times magnification. Large pores of about 100 μm are observed in the SEM photograph of FIG. 14.

[0042] The polishing rate PR, surface roughness Sa, and number of scratches of the SiC wafer after the polishing test of Polishing Test 1 were measured by the following methods.

[0043] [Test conditions for polishing test 1] Workpiece: 4-inch diameter SiC wafer (0001) Si surface, tilt angle 4° Workpiece rotation speed: 60 rpm Polishing pad diameter: 300mmφ Polishing pad rotation speed: 60 rpm Polishing pressure: 42kPa Polishing liquid: KMnO4 (0.25mol / l) pH=3.2 (Abrasive grains not included) Polishing liquid flow rate: 10ml / min Polishing time: [Comparative example 1] 200 hours [Comparative Example 2] 70 hours [Example 5] 2 hours [Example 6] 2 hours [Example 7] 2 hours [Example 8] 2 hours [Example 9] 2 hours

[0044] [Method for measuring polishing rate PR] The difference in mass of the SiC wafer before and after the polishing test was determined using an analytical balance, and the amount of polishing (wear thickness) was calculated from the known density of the SiC wafer and the surface area of ​​the polished surface. The polishing rate PR (nm / h) was calculated by dividing the amount of polishing by the polishing time.

[0045] [Surface roughness Sa measurement method] The surface roughness Sa of the surface profile of the polished surface of the SiC wafer after the polishing test was measured using a white light interference microscope (Hitachi High-Tech VS-1330), and the arithmetic mean surface roughness Sa specified in ISO25178 was calculated.

[0046] [Method of measuring the number of scratches] The entire surface of the polished SiC wafer was observed with a confocal differential interference microscope (Lasertec Corporation, OPTELICS HYBRID), and scratches detected by the equipped scratch judgment software were counted as one.

[0047] FIG. 6 shows the polishing test results (polishing rate PR (nm / h) and surface roughness Sa (nm) of the polished surface) and the number of scratches (count) when using Example products 5 to 9 and Comparative examples 1 to 2, respectively. The polishing results show that Example products 5 to 9 have a higher polishing rate PR (nm / h) than Comparative examples 1 to 2. Also, Example products 5 to 9 have a better surface roughness Sa than Comparative examples 1 to 2. SiC wafers are polished while supported by the edges of bubbles, but Example products 5 to 9 have fine pores of about 0.2 to 3 μm, so they are supported by many edges, which is thought to be the reason for the above polishing results.

[0048] As described above, according to the resin porous body 17 of this embodiment, the base resin is PES (polyethersulfone) resin or PVDF-HFP (a copolymer of 80% polyvinylidene fluoride and 20% hexafluoropropylene) resin, which has high resistance to oxidizing agents and abrasion, and the size of the micropores formed in the base resin is 0.2 to 3 μm. Therefore, since the resin porous body 17 is used as the base resin of a compound semiconductor polishing pad used in polishing by the CMP method, which uses a resin polishing pad that mechanically promotes polishing and a polishing liquid that chemically promotes polishing when polishing a difficult-to-polish wafer by the CMP method, a compound semiconductor polishing pad that is free of scratches and can maintain the polishing rate and surface roughness for a long time can be obtained.

[0049] Since the resin porous body 17 of this embodiment has micropores with a size of 0.2 to 3 μm, when the polishing pad 18 to which the resin porous body 17 is applied is used for polishing a hard-to-polish compound semiconductor wafer by the CMP method using a polishing liquid containing a permanganate-based strong oxidizing agent, there are no scratches and the polishing rate and surface roughness can be maintained for a long time.

[0050] The manufacturing method of the resin porous body 17 constituting the polishing pad 18 of this embodiment includes a melt preparation process P1 in which a base resin and lactose having high resistance to oxidizing agents and abrasion are melted in an organic solvent to obtain a melt, a molding process P2 in which the melt is molded into a thin plate to obtain a thin plate-like molded body, a precipitation process P3 in which the thin plate-like molded body is placed in cold water whose temperature is lower than the melting point of lactose to finely precipitate lactose solids in the thin plate-like molded body, a replacement process P4 in which the thin plate-like molded body that has undergone the precipitation process P3 is placed in hot water whose temperature is higher than the cold water to replace the lactose solids finely precipitated in the thin plate-like molded body and the organic solvent in the thin plate-like molded body with water, and a drying process P5 in which the thin plate-like molded body is dried until all moisture is removed from the thin plate-like molded body. As a result, the resin porous body constituting the polishing pad 18 is made of PES resin or PVDF-HFP resin, which has high resistance to strong oxidizing agents, and fine pores are formed within the PES resin or PVDF-HFP resin, so that when polishing difficult-to-polish wafers, there are no scratches and the polishing rate PR and surface roughness Sa can be maintained for a long time.

[0051] The base resin in this embodiment is PES (polyethersulfone) resin or PVDF-HFP (a copolymer of 80% polyvinylidene fluoride and 20% propylene hexafluoride) resin, so that a resin porous body having high resistance to oxidizing agents and abrasion is obtained.

[0052] The organic solvent in this embodiment is N-methyl-2-pyrrolidone or 2-pyrrolidone. These solvents dissolve the base resins, PES (polyethersulfone) resin and PVDF-HFP (copolymer of 80% polyvinylidene fluoride and 20% propylene hexafluoride), and lactose, so that in the precipitation step P3, the thin plate-shaped body is left in cold water at a temperature lower than the melting point of lactose, thereby allowing the lactose solid to be finely precipitated in the thin plate-shaped body.

[0053] The organic solvent in this embodiment is a solvent that disperses in water and dissolves PES (polyethersulfone) resin and PVDF-HFP resin. By leaving the thin plate-shaped molded body that has been subjected to the precipitation step P3 in hot water that is higher than the temperature of the cold water and the melting point of the organic solvent, the lactose solid finely precipitated in the thin plate-shaped molded body and the organic solvent in the thin plate-shaped molded body can be replaced with water.

[0054] In this embodiment, the precipitation step P3 is to leave the thin plate-shaped body in cold water at 5 to 10° C., and the replacement step P4 is to leave the thin plate-shaped body that has been subjected to the precipitation step P3 in warm water at 40 to 60° C., which is sufficiently higher than the melting point of lactose. As a result, after the lactose solid can be finely precipitated in the thin plate-shaped body in the precipitation step P3, the lactose solid precipitated in the thin plate-shaped body and the organic solvent in the thin plate-shaped body are replaced with water in the warm water.

[0055] The resin porous body of this embodiment constitutes a polishing pad 18 having fine pores, and this polishing pad 18 allows the workpiece 16 to be polished without scratches using a polishing solution PF containing a permanganate-based strong oxidizing agent, thereby obtaining a polishing pad 18 that can maintain the polishing rate PR and surface roughness Sa for a long period of time.

[0056] The resin porous body of this embodiment has micropores with an average diameter of 0.2 to 3 μm. This has the advantage that when the workpiece 16 is polished with the polishing pad 18 made of the resin porous body, the edges of the many micropores contribute to the polishing mechanism, making it difficult for scratches to occur, and thus favorable polishing rate PR and surface roughness Sa can be obtained.

[0057] The polishing pad 18 of this embodiment has 48.4 to 85.2 volume % pores, 14.8 to 51.6 volume % base resin, and a durometer hardness of 12.5 to 58.1, so it is free of scratches and can maintain the polishing rate PR and surface roughness Sa for a long time.

[0058] Although the preferred embodiment of the present invention has been described in detail above with reference to the drawings, the present invention is not limited to this embodiment and may be carried out in other embodiments.

[0059] For example, in the above-mentioned examples, lactose was used as a disaccharide (an oligosaccharide consisting of two monosaccharide molecules), but instead of lactose, maltose, sucrose, cellobiose, etc. may be used. Any disaccharide may be used as long as it is a solid that dissolves in a water-soluble solvent and water.

[0060] Furthermore, the polishing solution PF in the above-described embodiment does not contain abrasive grains, but it may contain abrasive grains.

[0061] Further, the polishing solution PF in the above-mentioned embodiment contains a permanganate-based strong oxidizing agent such as potassium permanganate (KMnO4), but other strong oxidizing agents may be added.

[0062] Furthermore, the polishing pad 18 in the above embodiment does not contain abrasive grains, but it may contain abrasive grains.

[0063] Furthermore, although the resin porous body in the above-mentioned embodiment was used as the polishing pad 18, it may also be used for other purposes, such as a water-adhesive pad for fixing a compound semiconductor wafer on a polishing table, synthetic leather, an anti-vibration sheet, a sound-absorbing material, a water-absorbing and water-retaining body, a separator or separation membrane for a fuel cell, etc.

[0064] Note that the above is merely one embodiment, and other examples are not provided, but the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit of the present invention. [Explanation of symbols]

[0065] 16: Workpiece (hard-to-polish compound semiconductor wafer) 17: Porous resin 18: Polishing pad (compound semiconductor polishing pad made of resin porous body) PF: Polishing fluid

Claims

1. A method for producing a resin porous body having high oxidant resistance and abrasion resistance and fine pores, comprising the steps of: a melt preparation step of melting a base resin, which is a PES (polyethersulfone) resin or a PVDF-HFP (a copolymer of 80% polyvinylidene fluoride and 20% propylene hexafluoride) resin, and a disaccharide in an organic solvent to obtain a melt; a molding step of molding the molten material into a thin plate to obtain a thin plate-shaped body; a precipitation step of leaving the thin plate-like molded body in cold water at a temperature lower than the melting point of the disaccharide to finely precipitate a solid of the disaccharide in the thin plate-like molded body; a replacement step in which the thin plate-shaped body that has been subjected to the precipitation step is left in hot water having a temperature higher than that of the cold water, and the disaccharide solid finely precipitated in the thin plate-shaped body and the organic solvent in the thin plate-shaped body are replaced with water; A drying step of drying the thin plate-like molded body until all moisture is removed from the thin plate-like molded body. The present invention relates to a method for producing a porous resin body.

2. The organic solvent is N-methyl-2-pyrrolidone or 2-pyrrolidone. The method for producing a resin porous body according to claim 1.

3. The organic solvent is a solvent that disperses in water and dissolves the PES (polyethersulfone) resin and the PVDF-HFP (a copolymer of 80% polyvinylidene fluoride and 20% propylene hexafluoride) resin. The method for producing a resin porous body according to claim 1.

4. The precipitation step is a step of leaving the thin plate-shaped body in the cold water at 5 to 10°C, and the replacement step is a step of leaving the thin plate-shaped body having been subjected to the precipitation step in the warm water at 40 to 60°C. The method for producing a resin porous body according to claim 1.

5. A compound semiconductor polishing pad is composed of a resin porous body having a base resin which is a PES (polyethersulfone) resin or a PVDF-HFP (copolymer of 80% polyvinylidene fluoride and 20% propylene hexafluoride) resin and micropores formed in the base resin, and is used to polish a hard-to-polish compound semiconductor wafer using a polishing solution containing a permanganate-based strong oxidizing agent, The compound semiconductor polishing pad has 48.4 to 85.2 volume % of pores, 14.8 to 51.6 volume % of the base resin, and a durometer hardness (Type-D) of 12.5 to 58.

1.

1. A compound semiconductor polishing pad comprising:

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