TW201109119A - Supporting pad - Google Patents

Abstract

A supporting pad is provided which has a supporting face with heightened flatness precision and can improve the in-plane evenness of an object to be polished. The supporting pad (10) includes a urethane sheet (2). The urethane sheet (2) has been formed by the wet solidification method and has a supporting face (Sh) for supporting an object to be polished. The urethane sheet (2) has a skin layer (2a) of a microporous structure, and has many cells (3) formed on the inner side of the skin layer (2a) and having such a size that the cells (3) extend over almost the whole thickness of the urethane sheet. In the urethane sheet (2), the bottoms of the cells (3) are located in the range of from the back side (Sr) to a depth of 0.1t therefrom, provided that t is the thickness of the urethane sheet (2). In a lower layer part (Pr) sandwiched between the section which is located 0.1t inward from the back side (Sr) and is parallel to the back side (Sr) and the section which is located 0.4t inward from the back side (Sr) and is parallel to the back side (Sr), the urethane sheet has a porosity, concerning the cells (3), regulated to 75-95%. In polishing, the urethane sheet (2) shows an increased compressive deformation in the lower layer part (Pr).

Description

[Technical Field] The present invention relates to a holding mat, and more particularly to a holding mat having a resin sheet for holding a holding surface for an object to be polished. This resin sheet is formed into a longitudinal foam by a wet coagulation method. [Prior Art] The surface (processed surface) of various materials (objects to be polished) such as a glass substrate for a semiconductor or a substrate for a hard disk (Fpd) for use in semiconductors is improved. Flatness is thus performed by using a grinder having two platforms arranged in opposite directions. In the above-mentioned semiconductor wafers, the semiconductor wafer (WF) is required to be manufactured as a polishing process because it is required to be compacted in accordance with the miniaturization of the portable device or the like to be applied. Large-scale

tendency. In addition, the glass substrate for FPD tends to be large and thin, and the glass substrate of the object to be polished tends to be larger and thinner in accordance with the increase in size of the FPD itself. In the case of such a large-scale, thin-plated 7-grinding material, the requirement for flatness is also becoming more and more important. For example, when the object to be ground is subjected to single-side grinding, 'in the grinding machine One of the platforms is provided with a polishing pad, and on the other platform, the object to be polished is kept opposite to the polishing pad, and during the grinding process, the abrasive particles are supplied between the object to be polished and the polishing pad. The slurry of the granules is subjected to a grinding pressure (pressing force) to the object to be ground. In order to avoid damage due to contact between the object and the platform, it is usually placed on a platform for holding the object to be polished. . That is, by holding the mat to temporarily hold the 201109119 abrasive in the grinding process. In the above-mentioned Japanese Patent Application Laid-Open No. 2006-62059, a soft urethane sheet (resin sheet) having a hair fring structure formed by a wet coagulation method is used. The grinding treatment is used as a holding mat. In the sheet towel of the amino acid formic acid formed by the = method, since the surface (holding surface) of the surface layer 2) has smoothness, the object to be polished is retained. Further, on the inner side of the surface layer, vertical foaming having a size of approximately eliiS is formed. Therefore, when subjected to grinding processing: when the pressure is compressed, the longitudinal foaming can be used to buffer the 'inferiority of the workpiece due to the force of the grinding (four) force, causing the stress to concentrate on the enthalpy. On the convex portion of the object to be polished, this stress concentration portion may again be caused by grinding and causing uneven grinding. On the other hand, when the cushioning property of the vertical type increases, the stress on the object to be polished is less likely to occur: although the sentence uniformity t can be used to raise the surface of the object to be polished, but at the same time, there is a degree of collapse. It becomes larger and causes the possibility that the pad is also ground. Therefore, in the wet solidification method, the selection of the body and the various additives are used to adjust the size of the foam, and the density of the portion of the amino acid obtained by the wet coagulation method and the resin between the foams is not. In the case of the foam forming portion and the resin portion, the amount of compressive deformation when the grinding pressure is applied during the grinding = working time is equal to the thinning of the above-mentioned type; The requirement of the flatness of the twist. That is, when the density of the unevenness on the holding mat 4 201109119 is different, the stress applied to the object to be polished is locally different, so it becomes difficult to apply the surface: The whole area is subjected to the uniform-ground grinding process and the damaged surface (four). If the unevenness of the compression deformation can be reduced and the flatness accuracy of the holding surface can be improved, the in-plane uniformity of the object to be polished can be satisfied. [Explanation] [Summary of the Invention] The cloud is in the above-mentioned conventional problems, and the object of the present invention is to provide a kind of holding pad, in particular, to improve the flatness accuracy of the holding surface and to improve the in-plane of the object to be polished. In order to solve the above problems, the holding mat of the present invention is provided with a resin sheet having a holding surface which can be used to keep the object to be polished, which is formed by a wet coagulation method. In the longitudinal direction of the resin sheet, the foamed bottom portion is formed in a range from the back surface of the holding surface to the inner side by 10% by weight. The thickness from the back surface to the inner side is 10% of the body's cross section parallel to the back surface, and 40% of the total thickness from the back side to the inner side, a section parallel to the back surface, and the space of the lower part of the two sections is 70% In the present invention, the resin sheet has a porosity of 7 〇 (four) or less in the lower layer portion of the holding surface on the back surface side of the holding surface, so that the lower layer portion can be used to secure the buffer. Sexuality, so that the load applied to the object to be polished can be dispersed, so that the foaming shape of the lower layer portion when compressed by the grinding process can be reduced, and the pair is ground. In addition, the in-plane uniformity of the object to be polished can be improved by the accuracy of the flatness of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface. On the cross section parallel to the holding surface, the average pore diameter of the pore formed by the foaming is set to A, and the maximum pore diameter of the pore formed by the foaming in the lower cross section of the 'parallel to the holding surface' is set to B. In addition, the ratio B/A is preferably in the range of 2 〇 to 5 。. Further, the entire thickness of the inner surface from the holding surface is 10 /. The flaw, the section parallel to the holding surface, and the orientation from the holding surface 40% of the thickness of the inner side is 'the cross section parallel to the holding surface'. The porosity of the upper layer portion covered by the two cross sections may be 35% or more and 55% or less. The void ratio of the lower portion of the resin sheet is preferably It is 75% or more and 90% or less, and the void ratio of the upper layer portion is preferably 40% or more and 50% or less. On the lower layer portion of the resin sheet, the area per unit area in the cross section parallel to the holding surface shows the ratio at which the ratio of the total area of the pores formed by the foaming is maximum, and the maximum value of the ratio may be 80%. Above 95%. The resin sheet may also be formed of a polyurethane resin. The polyurethane resin in the respective foaming of the resin sheet may also be formed into a microporous shape. In this case, it is preferred to set the 1 〇 〇 % modulus value of the polyurethane resin to less than 20 MPa. It is also possible to apply an adhesive material for mounting on a grinder on the back side of the resin sheet. At this time, a support material for supporting the resin sheet may be bonded between the resin sheet and the adhesive. According to the present invention, since the porosity of the lower layer portion having a certain thickness portion in the back surface side of the holding surface is between 7% and 95%, the cushioning property can be ensured by the lower layer portion. The load on the polishing material can be dispersed, so that the foaming shape change of the lower layer portion when the film is compressed by the polishing process can be reduced, and the burden on the object to be polished can be improved, thereby improving the flatness accuracy of the surface. The effect of the in-plane uniformity of the abrasive. [Embodiment] Hereinafter, a holding embodiment to which the present invention is applied will be described with reference to the drawings. The structure of the holding mat of the present embodiment is as shown in the figure. In the present embodiment, the holding mat 10 is provided with a urethane sheet 2 as a resin sheet made of a polyurethane resin. The polyamino phthalate sheet 2 is formed by a wet coagulation method, and has a holding surface Sh ° urethane phthalate sheet 2 for holding an object to be polished, and has a thickness of about several μηη across the holding surface Sh. Within the range, a dense microporous surface layer 2a is formed. That is, the surface layer 2a has a microporous structure. A plurality of foams 3 in a slightly uniform dispersion state are formed on the inner side (inside) of the surface layer of the urethane sheet 2. The size of the foam 3 is approximately the width of the urethane sheet 2 The size of the entire thickness is approximately long in the thickness direction and has a rounded conical shape. The amine-based methacrylate sheet 2 has a surface layer 2a, so that no foaming is formed on the holding surface Sh. In the urethane sheet 2, the foam 3 is formed in a range from the back surface of the holding surface Sh (hereinafter referred to as the back surface Sr) to the inner thickness of 10% by weight. In the polyurethane resin between the foams 3, micropores (not shown) smaller than the foaming 3 are formed. In the urethane sheet 2, 'the microporous surface layer 2a, foam 3 And the microporous mesh-like shape 201109119 is connected to each other and has a foaming structure. In order to form a continuous foaming shape, in the vinegar sheet 2, the 1G from the back core is oriented toward the inner thickness of the inner shell. % of the air surface parallel to the back Sr, and the distance from the inside is Almost the entire amount of the & Sr stitch sectional plane, the two p-sectional view of the package porosity lower nip portion, based adjusted to be between 70% to 95% or more. That is, when the thickness of the ?-f-ester sheet 2 is set to t, the section from the back surface Sr toward the inside: a section having a wide thickness portion and a section of the thickness portion facing the inner side 'the lower layer portion & In the case, the void ratio based on the foaming 3 is in the range of 75 to 95%.相对 , , 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车 车The void ratio of the upper layer of the two sections is adjusted to be less than or equal to 55/〇. That is, the section from the thickness of the thickness of the inside of the holding surface % to the inside of the O.lt, and the section of the thickness of the portion facing the inner side, the upper part of the two sections is covered by the void ratio of the foaming 3 Between 35~55% range. The void ratio of the upper layer portion Pb or the lower layer portion Pr can be adjusted by the selection of the polyurethane resin to be used and the conditions of the wet solidification method (described later). Further, in the urethane sheet 2, the cross section from the holding surface is a section which is parallel to the holding surface sh in a thickness of all (four) 1% by weight, and has a hole formed according to the foaming 3, when the hole The average aperture is set to A while the lower part is clever on the back 8 201109119

The ratio of the total area of each single hole in the Si* parallel profile (below: two factors = = face = hole formed on the face, the maximum hole of the hole = B, riding the large aperture B to the average aperture The adjustment of a is in the range of 20 to 50. That is, the addition of the average pore diameter of the foam adjacent to the holding surface Sh is such that the foam is formed in the opening of the lower layer portion pr. In addition, the maximum opening ratio can be adjusted to be between 80% and 95%. S° sh urethane sheet 2 $, she is adjacent to the holding surface" The hole formed in the cross section, the hole formed in the cross section parallel to the back surface Sr and the back surface Sr is in a state of being close to each other. As shown in Fig. 2(A), the adjacent holding surface Sh is separated from the holding f sh The position of the thickness 1 of the urethane sheet 2 is 1 〇 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置 位置(Position of arrow c) ^ In this case, as shown in Fig. 2(B), in the section of the B_B line adjacent to the north of the holding surface, The holes formed by the foaming 3 are alienated from each other. Conversely, as shown in Fig. 2(C), the holes formed by the foaming 3 in the c_c line section adjacent to the back surface Sr are close to each other. In the holding mat 10, a double-sided tape 7 as an adhesive material is attached to the back surface Sr side of the urethane sheet 2 to mount the holding mat 10 to the grinder. In the base material shown, a pressure-sensitive adhesive layer (not shown) such as an acrylic adhesive is formed on both surfaces of the substrate. The base material is, for example, Poly Pair 2, 201109119 ethylene formate (hereinafter, simply referred to as PET.) A flexible film such as a film. The double-sided tape 7 is bonded to the urethane sheet 2 by an adhesive layer on one side of the substrate, and the other side (urethane) The surface of the adhesive layer on the opposite side of the sheet 2 is covered with the release paper 8. Further, in the present embodiment, the beauty material of the double-sided tape 7 can also be used as the supporting amine phthalate sheet 2 Branch material = below, will explain the way to keep the pad, keep the pad 1 〇 will be wet The urethane formed by the solid method is prepared by laminating the sheet 2 and the double-sided tape 7. That is, the preparation step of preparing the polyurethane resin solution, and coating the polyurethane resin solution on the film-forming substrate And a coagulation regeneration step of coagulating the polyurethane resin solution to form a polyurethane resin in the coagulating liquid, washing the flaky polyurethane resin, drying and drying the drying/drying step, and bonding the obtained amine group A The lamination step of the acid ester sheet 2 and the double-sided tape 7 is specifically made to maintain a uniform enthalpy. Hereinafter, the steps will be described in the order of the steps. The preparation steps are a mixture of a polyurethane resin and a water-miscible organic resin capable of dissolving the polyurethane resin. The solvent and the additive dissolve the polyurethane resin. As an organic solvent, hydrazine, dimethyl decylamine (hereinafter abbreviated as DMF) or N,N-dimercaptoacetamide (DMAc) may be used. In the present embodiment, DMF is used as an organic solvent. Polyurethane tree The ruthenium can be selected from one of resins such as polyacetal, poly, and polycarbonate. When it is considered that the foaming structure described above is to be formed, the viscosity of the resin solution which is soluble in 20% by weight of the polyurethane resin in the DMF is preferably selected to be 5 at a viscosity of 2 °C using a B-type rotational viscometer. ~l〇pa.s range of resin to make 201109119 use. Further, the polyurethane resin to be used preferably has a 100% modulus value of less than 2 MPa, and the polyurethane resin can be dissolved in DMF to be in the range of 10 to 30% by weight. Further, as the additive, since the size or the number (number) of the foam 3 is to be controlled, a pigment such as carbon black, a hydrophilic additive for promoting foaming, and a hydrophobic additive for stabilizing the regeneration of the polyurethane resin can be used. The obtained solution was defoamed under reduced pressure to obtain a polyurethane resin solution. In the coagulation and regeneration step, the polyurethane resin solution obtained in the preparation step is applied to the strip-shaped film-forming substrate in a sheet form at a normal temperature by a coating device such as a knife coater. At this time, the coating thickness (coating amount) of the resin solution can be adjusted by adjusting the clearance between the knife coater and the like and the film formation substrate. As the film-forming substrate, a resin film, a cloth ratio, a nonwoven fabric or the like can be used. In the present embodiment, a film made of PET is used. The polyurethane resin solution applied to the film-forming substrate is continuously guided to a coagulating liquid (aqueous coagulating liquid) containing water as a main component of the polyurethane resin. In order to adjust the rate of regeneration of the polyurethane resin, an organic solvent such as a polar solvent other than DMF or DMF may be added to the coagulating liquid. However, in the present embodiment, water is used. In the coagulating liquid, first, a film is formed at the interface between the polyurethane resin solution and the coagulating liquid, and a microporous layer which can constitute the surface layer 2a is formed in the polyurethane resin close to the film. Next, the polyurethane resin having a continuous foaming structure is regenerated by the diffusion of DMF in the polyurethane resin solution into the coagulating liquid and the incorporation of water into the polyurethane resin. At this time, since the PET film formed on the film-forming substrate, water (coagulating liquid) cannot penetrate, so on the surface

[S 11 201109119 The replacement of DMF and water occurs on the 2a side, and the film formation substrate side forms foam 3 which is larger than the surface layer 2a side. Here, the formation of foam accompanying the regeneration of the polyurethane resin will be described. In the polyurethane resin, since the cohesive force becomes large, the surface layer 2a is formed by rapidly regenerating in the polyurethane resin close to the skin. In the present embodiment, a polyurethane resin having a 〇〇% % modulus value of less than 20 MPa is used. It is also shown that the viscosity of the polyurethane resin solution is in the range of 5 to 1 〇pa.s. That is, a low-viscosity polyurethane resin solution is dissolved in a low-viscosity polyurethane resin solution. Therefore, after the formation of the surface layer 2a, the polyurethane resin in the polyurethane resin lapis solution before solidification moves to the surface layer side and aggregates, and the amount of the polyurethane resin decreases with the surface layer on the film-forming substrate side. Compared with the 2a side, foaming 3 is formed. In the case of the lower layer portion Pr, the void ratio is increased due to the enlargement of the foaming 3 as compared with the upper layer portion Ph. Further, the desolvent from the DMF polyurethane resin solution, that is, the surface layer 2a, the foam 3 and the micropores are formed by the substitution between DMF and water, and the surface layer 2a is microporous and foamed. And the microporous system is connected to each other in a mesh shape. Further, since the polyurethane resin is recyclable on the film-forming substrate, the opening of the foam 3 is not formed in the back surface formed in contact with the surface of the film-forming substrate. In the washing/drying step, the polyamine vinegar resin to be regenerated in the regeneration step is washed with a washing liquid such as water to remove the residual resin remaining in the polyurethane resin and dried. In the case of polyamine resin = drying, this embodiment is a cylindrical dryer containing a heat source cylinder. Drying is carried out by passing the polyamine brewing resin along the circumferential surface of the cylinder through 12 201109119. The obtained carbamic acid vinegar thin 4 2 was taken into a reel shape. In the layering step, the urethane sheet 2 and the double-sided tape 7 produced by the wet coagulation method are attached. At this time, the back surface Sr of the urethane sheet 2 was bonded to the double-sided tape 7. Next, after cutting into a desired shape and size such as a circle or a polygon, it is checked whether there is damage or adhesion of dirt or foreign matter, and the holding pad 10 is completed. — Next, the effect achieved by the holding mat 1本 of the present embodiment will be described. In order to facilitate the understanding of the description, the foaming structure of the amino formate vinegar sheet formed by the conventional wet coagulation method will be described. In the conventional wet coagulation method, the polyamine vinegar resin solution applied to the film-forming substrate such as a PET film is condensed in a coagulating liquid such as water. Therefore, as shown in Fig. 3, in the urethane sheet 12 constituting the conventional holding crucible (9), the surface layer 12a at the initial stage of the wet coagulation is also formed on the inner side to form a trans-amine. A large amount of foam 13 of the entire thickness of the base formic acid sheet 12 was obtained. The foam 13 has a smaller aperture on the sh side of the face of the female face than the hole on the side of the back Sr, and is formed in the vertical direction along the thickness direction. In the outer layer of the carbamic acid from the first sheet 12, a hole formed in a section parallel to the holding surface Sh, : the two sides Sh, and a hole formed in a section parallel to the back surface 2 and the back surface Sr, The two apertures 2 are alienated from each other. * The hole of the foam 13 on the side of the back surface Sr is larger than the hole of the side of the holding surface Sh, so that the degree of the separation becomes larger on the side of the holding surface Sh. That is, as shown in Fig. 4 (A), the neighboring 201109119 near holding surface Sh' and the holding surface sh are oriented inwardly from the position of the thickness of the urethane sheet 12 by 1% by weight (the position of the arrow b), and the vicinity The back surface Sr is located inside the 10% portion of the thickness of the bismuth carbazate sheet 12 toward the inside of the back surface Sr (the position of the arrow c). In this case, as shown in the fourth (B) diagram, the adjacent holding surface On the bb line cross section of Sh, the pores formed according to the foam 13 are separated as shown in Fig. 4(C), and the pores formed by the foam 13 are also formed in the CC line cross section adjacent to the back surface Sr. In the CC line section, the hole formed is closer to the hole formed in the cross section of the B_B line, but is formed on the cross section adjacent to the back surface Sr of the urethane sheet 2 constituting the above-described holding pad 10. The pores are formed in an alienated manner (see the second (C) diagram in the urethane sheet 12 in consideration of the same as the upper layer portion ph and the lower layer portion Pr in the above-described urethane sheet 2). In the region, the porosity of the upper layer is about 3 to 45%, and the porosity of the lower layer is about 70% or less. In the case of the conventional retention crucible 20 using such an aminophthalate sheet 12, Density unevenness occurs between the portion of the foam 13 and the resin portion between the foamed n. Therefore, the foamed portion and the resin portion are different in the amount of compressive deformation when subjected to the polishing pressure during the polishing process, and thus become It is difficult to satisfy the height flatness required for the object to be polished. That is, in the holding mat 20, the density unevenness occurs, so that the magnitude of the stress applied to the object to be polished is locally different. It is difficult to spread the entire processing surface of the object to be polished The uniform polishing process is performed in the area. Therefore, the flatness of the high-precision 201109119 required for the semiconductor WF and FPD glass substrates for the purpose of thinning and increasing the thickness of the above-mentioned tends is not sufficient. The urethane sheet 习 2 is a conventional holding mat 2 ,, when the polishing process is performed, when the polishing pressure is applied, the object to be polished is caught on the side of the holding mat 20, because of the cushioning amine group The acid ester sheet 12 is compressed to cause stress on the abrasive. In the case where the density of the holding mat 20 is uneven, that is, in the case where the foaming 13 is unevenly formed, the uneven density portion is present. The magnitude of the stress applied to the object to be polished is also different. Therefore, the pressing force applied to the object to be polished is changed regionally, so that it is difficult to uniformly polish the processed surface of the object to be polished across the entire region. As a result, in the workpiece to be polished after polishing, for example, the polishing margin between the outer edge portion and the center portion is different, and a phenomenon of so-called outer edge depression occurs. In other words, it is maintained. 20, the object to be polished is polished, and the flatness of the machined surface is impaired. As is apparent from the above, the conventional holding mat 20 cannot sufficiently satisfy the requirements of achieving high integration, defect-free base wiring, or displaying enamel images. The high-precision flatness required for the glass substrate for WF or FPD for semiconductors is relatively high. In the present embodiment, the back surface Sr of the urethane sheet 2 constituting the holding mat 1 is oriented inward. 10% by weight of the thickness t (O.lt portion), a section parallel to the back surface Sr, and a section which is 40% by weight (〇.4t parts) in the direction of the inside, and a section parallel to the back surface Sr, which is surrounded by the two sections The porosity of the lower layer portion Pr can be adjusted to be 70% or more and 95% or less. Further, the distance from the holding surface to the inner side is 10% of the total thickness, and the cross section parallel to the holding surface 811 is formed by foaming 3 The hole formed may be 疋 疋 15 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 2011 Can make the most of this hole When the large aperture is set to B, the ratio B/a can be adjusted to be in the range of 20 to 50. That is, the foamed pore size is a foam having a size of 2 〇 to 5 〇 which forms a foamed average pore diameter adjacent to the holding surface Sh, and the foaming ratio is such that the opening ratio formed in the lower layer portion Pr is shown as a maximum value. On the profile. Therefore, the lower portion Pr which can be formed by the soft foaming 3 can play the role of air cushioning, and the pressure (grinding pressure) applied to the workpiece can be easily dispersed. Further, when compressed by the grinding process, the foamed shape of the lower layer portion Pr is compressed and deformed in accordance with the pressure applied to the workpiece, whereby the warpage and the undulation of the object to be polished are combined to reduce the object to be polished. The burden (reverse stress)' can highly improve the flatness of the object to be polished. When it is considered that the amount of compressive deformation in the lower layer portion pr is to be secured, it is preferable to adjust the void ratio of the lower layer portion Pr to be in the range of 75 to 9 %. Further, in the present embodiment, the ratio of the total area of the holes formed by the foaming 3, that is, the maximum value of the aperture ratio, can be adjusted per unit area of the cross section parallel to the back surface Sr in the lower layer portion Pr. It is between 80% and 95%. Therefore, in the lower layer portion pr, particularly adjacent to the moon surface Sr, the pore diameter of the foaming 3 is enlarged, thereby ensuring sufficient cushioning property. Thereby, since the stress on the object to be polished can be equalized during the polishing process, the flatness can be improved. On the other hand, in consideration of the void ratio of the lower portion Pr, it is preferable to adjust the aperture ratio to a range of 82 to 9 % when considering the amount of compression deformation. In the present embodiment, the distance from the holding surface Sh of the urethane sheet 2 to the inner side is 1% by weight of the thickness t (0.1 part by weight), a cross section parallel to the holding surface Sh, and The inner side is 40% by weight (〇4t parts), and the cross section parallel to the holding surface Sh, and the void ratio of the upper layer Ph surrounded by the two sections can be adjusted to be 35% or more and 55% or less. Therefore, since the partition wall of the polyurethane resin is thicker than the lower layer portion Pr, the rigidity can be ensured, so that the object to be polished can be prevented from entering the holding mat side during the polishing process. When the rigidity of the holding mat is insufficient to cause the object to be polished to become large, the holding mat (urethane sheet) itself may be ground during the grinding process. On the other hand, since the holding mat 1〇 suppresses the sinking of the object to be polished, the polishing process can be continued without the amine phthalate sheet 2 being ground. When the porosity of the upper layer portion Ph is less than 35%, the increase in rigidity causes the hardness to be high, but it is difficult to achieve flatness. When it is considered to ensure rigidity by the concept of improving flatness, it is preferable to adjust the void ratio of the upper portion Ph to be in the range of 4 〇 to 5 〇%. Further, in the present embodiment, since the amino citrate sheet 2 has the above-described foaming structure, it is ensured that the upper layer portion Ph can have rigidity required to suppress the sinking of the workpiece, and the lower portion Pr can be secured. Since it has the cushioning property required for the equalization of the stress of the object to be polished, it is possible to achieve both rigidity and cushioning property by the single-piece amine phthalate sheet 2. Although a rigid resin sheet and a cushioning resin sheet may be bonded together, in this case, the two resin sheets may be peeled off from each other during polishing. Therefore, in order to maintain 塾10, the permeable urethane sheet 2 has both

F 17 201109119 and the cushioning property, the flatness of the object to be polished can be improved. Further, in the present embodiment, the holding mat 1 of the urethane sheet 2 made of a polyurethane resin is exemplified. The invention is not limited to this. Further, a resin such as polyethylene may be used to form a polyurethane resin, and any resin which can form the above-described foam structure by a wet coagulation method can be used. Further, in the tenth embodiment, the holding mat 10 in which the urethane sheet 2 and the double-sided tape 7 having the substrate are bonded is exemplified, but the present invention is not limited thereto. As long as the urethane sheet 2 and the holding mat for the adhesive for the grinder are provided, it can be used as a holding mat, for example, instead of the double-sided tape 7, and only various adhesives can be applied to the amine base. Acid sheet 2 (back side Sr). Further, in the present embodiment, the base material of the double-sided tape 7 can be exemplified as the support material for holding the mat 10, but the present invention is not limited thereto. It is also possible to form a support material between the urethane sheet 2 and the double-sided tape 7. A film made of PET or the like, or a non-woven fabric or the like can be exemplified as the support material, and there is no particular limitation. Further, although not specifically mentioned in the present embodiment, when the thickness unevenness of the urethane thin film #2 formed by the thirst quenching method becomes large, the acre is the holding surface Sh and the rear surface sr It may be parallel, and it is preferable to smooth the back mussel 1 by polishing or cutting in advance. In this way, the flatness of the holding surface Sh can be further improved. Π) According to the embodiment, the holding mat is produced by H: 4 lines. Further, it is described as Comparative Example 1 201109119. In Example 1, the resin used in the preparation of the urethane sheet 2 has a 1 〇〇〇/0 modulus value of less than 1 〇. MPa polyester MDI (methylene diphenyl diisocyanate, diphenylmethane monoisocyanate) polyamine vinegar resin is dissolved in DMF at a ratio of 18% by weight, and a hydrophilic additive of 丨% by weight is added to the polyurethane resin, and The polyurethane resin was added with 5% by weight of carbon black, and a polyurethane resin solution having a viscosity of 3.3 Pa·s was measured by a Brookfield viscometer. When the polyurethane resin solution was applied, the gap of the coating device was set to 0.7 mm. After the polyurethane resin solution was applied onto the film-forming substrate of the PET film, it was immersed in water (condensation liquid) at a temperature of 253⁄4 to completely regenerate the polyurethane resin. After the washing/drying, the side of the back surface Sr of the obtained urethane sheet 2 is polished, and the double-sided tape 7 is bonded to the polishing surface to complete the production of the holding crucible 10. Example 2 In Example 2, 'the same polyurethane resin as in Example , was used, and after dissolving in a ratio of 20% by weight in DMF, 1 weight of a polyamine resin was added; ϊ% of a hydrophilic additive, and Polyamine g was added to the resin to add 5% by weight of carbon black to prepare a polyurethane resin solution having a viscosity of 5.3 Pa.s as measured by a b-type rotational viscometer. The gap of the coating device was set to 1.0 mm. The polyurethane resin was coated on the film-forming substrate and then "immersed in water at a temperature of 10 ° C" to completely regenerate the polyurethane resin. After washing/drying, the obtained urethane sheet 2 is polished on the back surface Sr side, and the double-sided tape 7 is bonded to the polishing surface to complete the production of the holding mat 1〇. Example 3 201109119 In Example 3, use and examples! The same polyurethane resin was dissolved in a ratio of 21% by weight in DMF, and 3% by weight of a hydrophilic additive was added to the polyurethane resin, and 5 weight/min of carbon black was added to the polyurethane resin to prepare a b-type rotational viscosity. A polyurethane resin solution having a viscosity of 8.2 Pa*s was measured. The gap of the coating device was set to 1.0 mm. The polyurethane resin was coated on the film-forming substrate and then immersed in water of temperature 1 to completely regenerate the polyurethane resin. After washing/drying, the back side Sr side of the obtained urethane sheet 2 is polished, and the double-sided tape 7 is bonded to the polishing surface to complete the production of the crucible. Example 4 In Example 4, the same polyurethane resin as in Example 1 was used. After dissolving in a ratio of 21% by weight in DMF, 5% by weight of a hydrophilic additive was added to the polyurethane resin' and 5 weights were added to the polyurethane resin. The carbon black of % was prepared to prepare a polyurethane resin solution having a viscosity of 7.9 Pa.s as measured by a b-type rotational viscometer. The gap of the coating device was set to 1.0 mm. After coating the polyurethane resin solution on the film-forming substrate, it was immersed at a temperature of 25. In the water of (:, the polyurethane resin is completely regenerated. After washing/drying, the obtained S-side of the amino phthalic acid-pulverized sheet 2 is polished, and the double-sided tape 7 is bonded to the polishing surface. The production of the holding mat 1 was completed. Example 5 In Example 5, the same polyurethane resin as in Example 1 was used, and after dissolving in a ratio of 21.5 wt% in DMF, 1% by weight of a hydrophilic additive was added to the polyurethane resin. And adding 5% by weight of carbon black to the polyurethane resin to prepare a polyurethane resin solution having a viscosity of 9.5 Pa.s by a b-type rotational viscometer 20 201109119. The gap of the coating device was set to 1 '2 mm. After coating the polyamine vinegar resin solution on the substrate, it is immersed in water at a temperature of 10 ° C to completely regenerate the polyurethane resin. After washing/drying, the obtained urethane sheet 2 is obtained. The back side Sr side was polished, and the double-sided tape 7 was bonded to the polishing surface to complete the manufacture of the holding mat 10. Comparative Example 1 In Comparative Example 1, the same polyurethane resin as in Example 1 was used, and in the DMF, 21 was used. After the proportion by weight is dissolved A 1% by weight of a hydrophilic additive was added to the polyamine oxime resin, and 5% by weight of carbon black was added to the polyamine resin to prepare a polyurethane resin solution having a viscosity of 8.2 Pa.s as measured by a 3-type rotational viscometer. The gap of the coating device was set to 0.7 mm. After the polyurethane substrate was coated on the film-forming substrate, the mixture was melted at a temperature of 25. In the water, the polyurethane resin was completely regenerated. Thereafter, the back surface Sr side of the obtained urethane sheet 12 is polished, and the double-sided tape 7 is bonded to the polishing surface to complete the production of the holding mat 20. That is, the holding mat 20 of Comparative Example 1 is completed. It is a conventional holding mat (see also Fig. 3). The void ratio and the aperture ratio of the upper layer portion Ph and the lower layer portion pr are obtained for each of the obtained examples and the urethane bismuth hydride sheet of Comparative Example 1. The maximum value and the foaming pore ratio (Max/Min) indicating the ratio of the maximum foaming pore diameter to the minimum foaming pore diameter were measured. The void ratio was measured in the following manner. That is, a three-dimensional side X-ray computer was used. Fault imaging device (Dahe Science Co., Ltd. (YAMATO SCIENTIFIC) system, TDM10() (MS/Sp) riding scanning profile, obtaining continuous tomographic image from the holding surface Sh at a distance of 1 () μηι 201109119 The obtained tomographic image, 卩SEM with r Sca„dium J ( 01ympus s〇ft.Imaging s;luti ^ Two images of each of the two shades, the thick part is used as the opening part, and the target range (threshold value) can be consistent with the image. By accumulating the rich portion as the opening portion, the ratio of the total open area occupied by the f area is obtained as the opening. - The fault in the region of the lower portion Pr is "like the sum of the aperture ratios to be paid, and then removed. The ratio of the sum of the observed area of the upper layer portion and the lower layer portion Pr to the subsequent area can be utilized, for example, by using, for example, cutting a certain thickness portion from the surface of the urethane sheet by the cutting method, and passing through the SEM. A method of obtaining a void ratio by observing a grinding process, such as a microscope, is used as a simple method. The maximum value of the aperture ratio is determined by the aperture ratio obtained by measuring the void ratio. The foaming aperture ratio was determined as follows. In other words, the average opening diameter of the opening in the range of 3.3 mm 2 in the cross section parallel to the holding surface Sh is calculated by using "SCandium", which is 10% of the total thickness of the self-retaining surface. Foaming aperture. The "Scandium" is used to calculate the range of the 3 3 face 2 in the section showing the maximum value of the aperture ratio in the region of the lower layer, and the maximum opening diameter among the openings which are not in contact with the boundary of the observation region. Maximum foaming aperture. The ratio of the maximum bubble to the minimum foaming aperture was determined as the foaming aperture ratio. Since the minimum foaming pore diameter and the maximum foaming pore diameter correspond to the above average pore diameter A and maximum pore diameter B, respectively, the foaming pore diameter ratio can be expressed by the above-mentioned ratio B/A in Table 22 201109119. The porosity and the result of Comparative Example 1. Table 1 In Table 1 below, the respective examples and the ratio of the opening ratio and the foaming aperture ratio are listed.

Upper layer Ph lower layer Pr open porosity foaming aperture ratio flatness

Further, in the urethane sheet of Comparative Example 1, the void ratio of the upper layer adjacent Ph was 41.4%, and the void ratio of the lower layer portion pr was 68.6%. Further, as is clear from Fig. 5, the greater the degree of drought from the surface, that is, the closer the back center is, the larger the aperture ratio is, but the aperture ratio is only about 75% at the maximum. In contrast, in each of the urethane sheets 2 to ♦ of Examples 1 to 5, the void ratio of the upper layer portion is in the range of 38.3% to 5〇2%, and the void ratio of the lower layer portion & 77·2~88·3% range. Also, in the embodiment! In the urethane sheet 2, as is clear from Fig. 5, the cross section showing the thickness of ΙΟΟμη or more in the thickness region across the lower layer portion Pr continuously exceeds an aperture ratio of 8〇%. From the urethane sheet 2 of each of the examples, the void ratio of the upper layer portion ph was the same as that of the comparative example 1, and the porosity of the lower layer portion was large. Furthermore, from the measurement results of the foaming aperture ratio, it can be understood that in Comparative Example 23 201109119, the maximum opening diameter of the lower layer Pi·t is 18 7 times relative to the adjacent holding surface sh, which is relatively In each of the examples, it was shown to be 34.0 to 38.2 times the size. With respect to the evaluation of the polishing performance, the glass substrate for liquid crystal display (470 mm x 370 mm x 0.7 mm) was polished under the following polishing conditions using the holding crucible in each of the examples and the comparative examples, and the industrial standard (JIS B 〇) was used. 6〇1:, 82) is the reference method, and the flatness a is obtained from the fluctuation of the corrugated center. In the measurement of the flatness a, the surface roughness measuring machine (East Heng, manufactured by "Essence", SURfc〇m480A) was used, and the measurement was carried out according to the following measurement conditions. The width W between the convex portion (mountain portion) and the convex portion and the height s between the convex portion and the = portion (valley portion) are calculated from the measurement curve obtained by the unevenness on the surface of the substrate, and the width s is calculated For the horizontal axis, the degree S is the scatter diagram of the vertical axis. The approximate straight line of the equation s aW is obtained from the scatter plot, and the slope a is set to the final = flatness a after the grinding process. The higher the flatness, the larger the width w and the higher the height s. Therefore, the smaller the slope a, the more excellent the flatness. Grinding conditions using a grinder: OSCAR grinder (SP-1200 manufactured by SPEEDFAM) Grinding speed (number of revolutions): 61 rpm Processing pressure: 76 gf/cm2 Grinding slurry: grind grinding time: 30 min Wave, grain center undulation measurement condition evaluation length :90mm 24 201109119 Measurement speed: 3.0mm/s Interruption value: 0.8~8.Omm Film type: 2RC Measurement range: ±40.0μιη Tilt compensation··Smooth curve as shown in Table 1, using the holding pad of the comparative example In the polishing process, the flatness of the glass substrate after processing is shown as 〇.〇〇〇7. On the other hand, in the polishing process using each of the holding mats 10 of the Example 5, the flatness a 0.0003 G.GGG5' was displayed to be superior to Comparative Example i. Therefore, it can be clearly understood that the hair formed by the wet coagulation method = 3, the void ratio in the upper (four) Ph is formed in the range of 35 to 55%, and the porosity in the lower layer Pr_ is formed in the range of 7 〇~95 range. By maintaining the IMG' using the urethane urethane having the foaming 3, the flatness accuracy at the holding surface can be improved, and the in-plane uniformity of the object to be polished can be improved. The present invention provides a method for improving the flatness of the holding surface and improving the in-plane uniformity of the object to be polished, and contributes to manufacturing and sales, and is highly industrially applicable. By way of example, and not as a limitation. Any equivalent changes made without departing from the spirit and scope of the present invention shall be included in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing the structure of the embodiment of the present invention, q 25 201109119; and Fig. 2 is a view showing the formation of foam in the urethane sheet which constitutes the holding mat of the embodiment. A schematic diagram of a state in which the second (A) diagram is a cross-sectional view in the thickness direction of the urethane sheet, and the second (B) diagram shows the foaming on the B_B section in the second (A) diagram, respectively. A schematic illustration of the formed pores, and a second (C) diagram showing a schematic view of the pores formed by foaming on the c_c section in the second (A) diagram; FIG. 3 shows a conventional retention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 4 is a schematic view showing a state of formation of foam in an amino phthalate sheet constituting a conventional holding mat, wherein the 4 (A) diagram is a urethane sheet. FIG. 4(B) is a schematic explanatory view showing a hole formed by foaming on the BB section in FIG. 4(A), and FIG. 4(C) is respectively shown in the figure. 4(A) is a schematic explanatory view of a hole formed by foaming on the CC section; and FIG. 5 is a view showing a hole with respect to the self-constituting holding pad Yue holding surface of the base sheet of the starting esters of thickness, this thickness range in the respective cross-sectional 'graph comparing FIG hole opening rate is due to the foam formed. [Description of main component symbols] 2, 12: Amino phthalate flakes; 2a, 12a: surface layer; 3, 13: foaming; 26 201109119 7: double-sided tape; 8: release paper; 10, 20: retaining pad Sh : Keep the face;

Sr: the back;

Ph : upper part; and Pr : lower part.

Claims (1)

201109119 VII. Patent Application Range 1. A holding mat comprising: a resin sheet having a holding surface for holding one of the objects to be polished. The holding surface has a vertical shape formed by a wet solidification method. In the case where the resin sheet is formed from the back surface of the holding surface and the inner side is within a range of 10% by weight of the entire thickness, the bottom portion of the foam is formed, and the inner side of the resin sheet is formed from the back side toward the inner side. The distance is 1% of the total thickness, a cross section parallel to the back surface; and the inner side is 40% of the total thickness, and another cross section parallel to the back surface, the lower layer portion of the cross section The void ratio is between 7〇% and 95%. 2. The holding mat according to claim 2, wherein the sapling sheet is 10% of the total thickness of the smectic holding surface, and a section parallel to the holding surface a hole formed by the foaming, the hole has an average pore diameter of A, and in another cross section of the lower layer portion parallel to the holding surface, another hole is formed by the foaming, and the other When the maximum pore size of one hole is B, the ratio B/A system is in the range of 2 〇 to 5 。. 3. The holding mat according to the second aspect of the invention, wherein the tree slab sheet is 10% of the total thickness from the holding surface toward the inner side, and a section parallel to the holding surface; The inner side distance is 40% of the entire thickness, and the other cross section parallel to the holding surface has a porosity of 35% or more and 55% or less in the upper layer portion of the cross section. In the resin sheet, the porosity of the lower layer portion is between 75% and 90%, and the void ratio of the upper layer portion is introduced in the resin sheet. It is 4% or more and 50% or less. 5. The holding enthalpy according to the second aspect of the invention, wherein in the lower layer portion of the resin sheet, a hole formed by the foaming is displayed per unit area in a cross section parallel to the holding surface. A ratio of the total area is one of the largest sections, and the maximum value of the ratio of the section is between 80% and 95%. 6. The holding mat of claim 3, wherein the resin sheet is formed of a polyurethane resin. 7. The holding mat according to claim 6, wherein in the resin sheet, the polyurethane resin interposed between the foaming portions is formed into a microporous shape. 8. The retaining pad of claim 7, wherein the polyurethane resin has a modulus of less than 2 MPa. 9. The holding mat according to claim 1, wherein an adhesive material is applied to the back side of the resin sheet to mount the resin sheet in a grinder. The holding mat according to claim 9, wherein a support material is further attached to the resin sheet and the adhesive sheet to support the resin sheet. 29