TW201109123A - 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) formed by the wet solidification method and having a supporting face (Sh). The urethane sheet (2) has a skin layer (2a) formed therein and has many cells (4) formed on the inner side of the skin layer (2a). The cells (4) have such a size that the cells (4) extend over almost the whole thickness of the urethane sheet (2). The cells (4) each has been formed so that the diameter thereof in a lower layer (Pr) of the urethane sheet (2) is larger than the diameter thereof in an upper layer (Ph) of the sheet (2). The cells (4) have been formed so that the direction of cell formation in the upper layer (Ph) is evenly inclined in a certain direction relative to the thickness direction and that the direction of cell formation in the lower layer (Pr) is the same as the thickness direction. When the pad (10) is compressed in polishing, a stress is evenly imposed on the object being polished.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a retaining mat, and more particularly to a retaining crucible provided with a resin sheet having a retaining surface for retaining the object to be polished. 'The retaining surface is a large amount of upright foam which is formed by the wet coagulation method and spans the entire thickness. [Prior Art] At present, the surface (machined surface) of various materials (objects to be polished) such as a glass substrate or a hard disk substrate for a semiconductor wafer (WF) for semiconductor use is raised to be flat. Therefore, the grinding process is performed using a grinder having two platforms arranged in opposite directions. In such an object to be polished, in particular, a semiconductor wafer (WF) or a glass substrate for a parallel plane plate needs to have a high-concentration defect-free base layer wiring or display a high-quality image, and thus As a substrate on which these materials are based, the demand for the flatness of the substrate is increasing. For example, when one side of the object to be polished is polished, a polishing is performed on one of the platforms of the polishing machine. The pad, and on the other platform, is the way to keep the object in the object facing the pad. At the time of polishing, a polishing slurry containing abrasive particles (abrasive grains) is supplied between the workpiece and the polishing pad, and a polishing pressure (pressure) is applied to the workpiece. In order to avoid damage due to contact between the object and the platform, it is common to mount a holding mat on the platform for holding the object to be polished. That is, by holding the mat, it is possible to temporarily hold the object to be polished in the rubbing process. Further, in the holding mat, 甩201109123 can be used to suppress the template for lateral displacement of the object to be polished. Whether or not the template is to be used varies depending on the type of the object to be polished. For example, in the polishing process of the glass substrate for the parallel flat plate, the holding of the template is employed. A soft amine phthalate foam (urethanef 具有) having a foaming structure formed by a wet coagulation method as disclosed in Japanese Laid-Open Patent Publication No. H06-62-59 Am, a type of resin sheet, is used as a holding mat. In the polyurethane foam formed by the wet coagulation method, since foaming is formed across the entire thickness, when the foaming size is increased for the purpose of improving the cushioning property, The foaming size adjacent to the holding surface for the abrasive becomes large, and the rigidity thereof will be lowered. Therefore, when the cushioning property is too low, the stress applied to the object to be polished due to the polishing pressure causes a phenomenon of uneven force, and the stress is concentrated on the holding pad side of the object to be polished, and the large convex portion is trapped. On the top, this stress concentration is caused by excessive grinding and uneven grinding. On the other hand, when the cushioning property is improved, the stress applied to the object to be polished becomes less likely to cause uneven force, and thus the surface smoothness of the object to be polished can be improved, but it becomes trapped and enlarged, so that the stress is maintained. The mat itself is also subject to the possibility of being ground. The technique for suppressing the rigidity required for the sinking of the object to be ground and the cushioning property required for equalizing the stress on the object to be polished is parallel, and the prior art is as described in Japanese Patent Laid-Open No. 2005-11972. A holding mat which is bonded by two kinds of sheets having different foaming structures formed by a wet solidification method as disclosed in the publication. In the above technique, one of the sheets is used to ensure cushioning property, and the other sheet is used to exert its rigidity. 4 201109123 However, in the technique of Japanese Laid-Open Patent Publication No. 2006-62059, the surface (holding surface) of the surface layer formed by the wet coagulation method has smoothness, although Although the object to be polished is held relatively flat, there is still a problem that the high-precision flatness required for the above-described requirements is not satisfied. In the technique of Japanese Laid-Open Patent Publication No. 2005-11972, there is a case where unevenness in hardness occurs due to the influence of an adhesive or the like used for bonding the two kinds of sheets. In addition, there is also a problem that the two sheets are peeled off during the polishing process. When the polishing is carried out, the object to be polished is usually held while being held in a holding mat, and flattening is performed. Therefore, when the cushioning pad is compressed, stress is applied to the object to be polished. At this time, when the density of the holding mats is uneven, the magnitude of the stress applied to each of the uneven portions is different, and thus the pressing force is also changed in a regional manner, so that it becomes difficult to perform uniformity across the entire processing surface. Ground grinding process, thus destroying in-plane uniformity. For example, the grinding margin of the outer edge portion and the central portion of the object to be polished differs, so that a so-called outer edge indentation is generated. When the stress unevenness applied to the object to be polished can be reduced and the flatness accuracy of the holding surface can be improved, a required level of the flatness which satisfies the high-precision flatness can be obtained for the object to be polished. SUMMARY OF THE INVENTION In view of the above conventional problems, it is an object of the present invention to provide a retaining pad which, in particular, can improve the flatness of the holding surface and enhance the in-plane uniformity 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 for holding the ground material of the 201109123, which maintains the surface by a large number of upright type foaming of the thickness: In the method of forming the center portion of the thickness direction across the thickness direction, the tenth, and the 'from the resin sheet=forming direction' are inclined with respect to the thickness direction to form the foaming central portion to the resin sheet. The center of the thickness direction. In the thickness direction of the foamed end portion on the surface side, the above-mentioned foaming is formed in the direction of the thickness in the direction of the reinforcing direction, so that the unevenness occurs in the manner of tilting, and the polishing shrinkage is performed. It can still cross the entire area and equal stress, so it can improve the in-plane uniformity of the objects produced by the holding surface. In the case of the thickness of the resin sheet, the thickness of the resin sheet may be in the range of ::: ΐ θ% with respect to the entire thickness. The length of the foaming is preferably from the degree of doubling; the second:: the foaming end is still large. Further, the foaming may be formed so as to be in the thickness direction from the foamed end portion of the back side of the thick phase :: = :: phase holding surface. In the above-mentioned hair, the position perpendicular to the center of the cross section parallel to the holding surface is adjacent to the back surface of the holding surface, and the position where the parallel plane intersects can set the position. The hole formed by the same foaming on the cross section parallel to the back surface is evaluated. When the center Μ1 of the hole formed on the cross section of the holding surface at the center of the thickness direction is formed, the connecting line between the center M i 201109123 of the hole and the apex M2 of the holding surface side is formed as a beveled edge. In the right triangle, when the elevation angle when the vertex M2 is observed from the center M1 is defined as Θ, the foaming may be formed such that the elevation angle θ ranges from 3 〜 to 60 degrees. The resin sheet is formed into a long strip shape by a wet coagulation method. The foaming direction can be foamed from the central portion in the thickness direction to the foamed end portion on the holding surface side, and the resin sheet is formed in the thickness direction. In the longitudinal direction, the inclination is maintained to form L, and the foaming may be formed in the width direction intersecting the longitudinal direction in the thickness direction of the f to form a cross section in the width direction opposite to the longitudinal direction. The foaming system can be formed in the vertical direction. The resin sheet can be made of a polyurethane resin, and the foaming space can also be formed into a microporous shape. According to the present invention, the foaming direction is 'in the direction of the thickness from the central portion in the thickness direction of the resin sheet to the foamed end portion on the holding surface side, and is inclined in the fixed direction. Since it is formed, even if density unevenness occurs on the resin sheet during wet solidification, it is polished and reinforced, and when it is repeatedly shrunk, the entire area is doubled, and the stress generated on the object to be polished is equalized, so that the retention can be improved. The flatness accuracy of the surface and the in-plane uniformity of the object to be polished. [Embodiment] For the application of the embodiment of the present invention, the following description will be given with reference to the drawings. _ Hereinafter, the structure of the holding mat will be described. For example, the holding mat 10' of the 铋n' is a urethane sheet 2 having a resin sheet which is filled with polyurethane. Amino group 201109123 The acid sheet 2 is a holding surface Sh for forming a workpiece by a wet coagulation method. The urethane sheet 2 has a surface layer 2a formed with a dense microporous shape at a degree close to the holding surface Sh. That is, the surface layer 2a having the microporous urethane sheet 2 on the surface layer 2a is on the inner side (inside),

A large amount of foaming 4 is formed in a state of being slightly uniformly dispersed. The foaming * 2 has a thickness which is substantially the entire thickness of the amino acid vinegar sheet 2: it is small, and is formed in a longitudinal direction and has a rounded conical shape in the thickness direction. Since the urethane sheet 2 has the surface layer 2a, an opening of (4) 4 is not formed on the holding surface sh. In the polyamine vinegar resin which is foamed 4, it is formed with a larger number of micropores than the foamed 4 (not shown). The urethane crucible sheet 2 has a microporous structure of the surface layer 2a, a foamed 4 and a microporous mesh-like communication structure, and a continuous foaming structure in which a foam is formed into a continuous foaming state. The X-foaming 4 is from the central portion in the thickness direction of the urethane sheet 2 to the upper portion Ph of the holding surface Sh side and the back portion from the central portion in the thickness direction to the back surface of the holding surface sh, that is, the holding surface Sh is opposed thereto. The state of foam formation on the lower layer Pr on the side of the surface (hereinafter referred to as the back surface Sr) is different. That is, the foamed 4 is formed such that the pore diameter on the lower layer Pr is larger than the pore diameter on the upper layer Ph. In addition, the foaming 4 is a 'foaming forming direction' in the upper layer Ph to the foamed end portion on the holding surface Sh side, and is formed by being inclined uniformly in the fixing direction with respect to the thickness direction. The foam formation direction in the lower layer to the foamed end portion on the back surface Sr side is formed along the thickness direction. In other words, the foaming direction of the foaming 4 is, in the layer of 8 201109123, Ph + ' is in the direction inclined to the thickness direction (the direction of the arrow A of the drawing) and in the lower layer Pr, the thickness is along the thick Sound direction (arrow Β direction). Further, since the foam 4 is formed in an inclined state in the upper layer Ph, the vertical line passing through the center of the hole is formed by the hole formed by the foaming 4 in the cross section parallel to the holding surface Sh and the holding surface Sh. The cross section parallel to the cross section parallel to the back surface Sr and the back surface 81> is parallel to the back surface Sr, and is formed on the outer side of the hole formed by the same foaming 4. That is, as shown in Fig. 2(A), the inner surface of the holding surface Sh of the adjacent holding surface is 50 to 1 〇〇 " m (the position of the arrow a), the urethane sheet 2 The position in the center in the thickness direction (the position of the arrow b) and the inner position (the position of the arrow c) from the back surface Sr from the back surface Sr of about 50 to 100/m. In this case, as shown in Fig. 2(B), a hole Ha having a center is formed by the foaming 4 on the a-a cross section adjacent to the holding surface Sh. Similarly, a hole Hb having a center Mb is formed by the same foaming 4 on the bb section at the central portion in the thickness direction of the amino phthalate sheet 2; on the cc section adjacent to the back surface Sr, by the same The foam 4 forms a hole Hc having a center Mc. The hole Ha ^ center Ma, the center Mb of the hole Hb, and the center Me of the hole He are not aligned in the thickness direction, but are located at offset positions. That is, the vertical line L passing through the center Ma of the hole H a intersects the c-c cross section at the intersection Q. Therefore, the intersection Q is located outside the hole He. Further, if the radius of the hole He is Rc, and the distance between the center Me of the hole He and the intersection q is Lc, the distance Lc is about 2 to 5 times the radius rc. 201109123 Here, the visibility of the foam 4 formed by the urethane sheet 2 will be described. As shown in Fig. 3, in the cross section along the thickness direction of the lanthanum carbamate sheet 2, the cross section parallel to the holding surface sh in the center in the thickness direction (see the b_b cross section of Fig. 2 (8)). A hole having a center M1 is formed by foaming 4. The straight line ' in the direction in which the center M1 is orthogonal to the thickness direction (the vertical direction of FIG. 3) (the left and right direction of the third direction) and the vertex M2 on the holding surface Sh side of the foaming 4 are assumed to be combined with the amine. When the intersection point between the straight lines in the thickness direction of the urethane sheet 2 is p, a right-angled triangle having a line segment connecting the center M1 and the vertex M2 as a hypotenuse is formed. On this right-angled triangle, the vertex M2 is observed from the center M1 to form an elevation angle of zero. On the upper layer ph of the urethane sheet 2, the foamed 4 is formed when the elevation angle θ is in the range of 3 〇 to 6 〇. In this case, assuming that the length of the line segment connecting the center M1 and the intersection point p is X, and the length of the line segment connecting the vertex M2 and the intersection point P is y, the ratio of tan <9"/X' is between 〇58 and 173. In this case, the elevation angle 0 is obtained by photographing the internal cross section of the urethane sheet 2 in a non-destructive manner using a three-dimensional side X-ray computed tomography, and then in the image analysis apparatus, the center is Μι The value obtained after positioning with the vertex M2. In short, it is also possible to use a scanning electron microscope to photograph a section along the thickness direction in the longitudinal direction of the wet film formation, and then determine the center M1 and the vertex M2. Further, the elevation angle 0 is calculated. Further, the holding mat 1 is placed on the back surface Sr side of the urethane sheet 2, and a double-sided tape 7 for attaching the holding mat 1 to the grinder is bonded. The double-sided tape 7 Further, a substrate (not shown) is provided, and a pressure-sensitive adhesive layer (not shown) such as an acrylic adhesive is formed on both surfaces of the material of 2011009123. The substrate is, for example, polyethylene terephthalate. (hereinafter, referred to as PET. A flexible film such as a film. The double-sided tape 7 is adhered to the amine phthalate sheet 2 by an adhesive layer on one side of the substrate, and the other side (with urethane hydride sheet 2) On the surface of the adhesive layer on the opposite side, the surface of the adhesive layer 8 is covered. Further, the base material of the double-sided tape 7 may also serve as a base material for the holding mat 10. Hereinafter, the manufacturing method of the holding mat will be carried out. It is to be noted that the 塾1 〇 is produced by laminating the urethane sheet 2 formed by the wet coagulation method and the double-sided tape 7. That is, the preparation step of preparing the polyurethane resin solution is A step of coating a polyurethane resin solution on a film-forming substrate, and solidifying the polyurethane resin solution in a coagulating liquid to form a polyurethane resin resin, a step of regenerating the polyurethane resin, washing the flaky polyurethane resin, and drying the drying/drying step And the lamination step of laminating the obtained urethane sheet 2 and the double-sided tape 7 is carried out, etc. The following steps are described in the order of the steps. The preparation step is a mixing of a polyurethane resin and a dissolvable polymerization. The water-miscible organic solvent and the additive of the amine vinegar resin dissolve the polyurethane resin, and examples thereof include N,N-dimethylformamide (hereinafter abbreviated as dmf.) or N'N-dimethylacetamide (DMAc). In the present embodiment, DMF is used as the organic solvent. The polyurethane resin may be selected from a resin such as a polyester resin, a polyether resin or a polycarbonate resin, and it is considered to form the above foam. In the structure, the resin 溶解201109123 dissolved in 20% by weight of polyurethane resin in DMF 'The viscosity measured at 25 ° C using B-type rotary viscometer can be between 3~l〇pa.s The range 'preferably is used for selecting a resin in the range of 3 to 6 Pa s. The polyurethane resin may be in the range of 1 〇 to 3 〇% by weight, preferably dissolved in DMF to be 15 25 mil % The scope. The viscosity of the polyurethane wax solution is not only dependent on the concentration and molecular weight of the polyurethane resin used, but also depends on the molecular structure. Therefore, these factors are comprehensively considered to select the polyurethane resin or to set the concentration. It is important. In addition, as the polyurethane resin for the holding mat, it is preferable to use it from 20 MPa or less, and it is more preferable to use 丨〇 MPa or less. By using a low modulus polyurethane resin, the adhesion of the object to be polished can be improved, and the holding power can be improved. Further, in order to control the size or amount (number) of the foam 4 and the foam formation in an inclined shape in the upper layer Ph, a pigment such as carbon black, a hydrophilic active agent, a hydrophobic active agent or the like may be used as the additive. Among these additives, various materials which are commonly used can also be used. The resulting 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. In this case, 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. In the present embodiment, the gap is adjusted so that the coating thickness is in the range of 〇.8 to 丨.2111111. As the film-forming substrate, a resin film, a cloth, a nonwoven fabric or the like can be used. In the present embodiment, a film made of ρΕτ is used. 12 201109123 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. Further, the temperature of the coagulating liquid can be set in the range of 15 to 20 C in this example. In the coagulating liquid, first, a film is formed at the interface between the polyurethane resin solution and the coagulating liquid, and microporous 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-forming solidified liquid of the film-forming substrate is not allowed to permeate, the DMF and the water are replaced on the surface layer 2a side, and the film-forming substrate side is formed with the foam 4 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 is increased, the polyurethane resin which is close to the film is rapidly regenerated to form the surface layer 2a. In the present embodiment, only the water is used as the coagulating liquid, and the temperature of the coagulating liquid is set to a relatively low temperature of 〜5 to 2 〇 °C. Thereby, a dense surface layer 2a is formed on the surface where the polyurethane resin solution is rapidly solidified on the portion in contact with water, so that the interdiffusion between water and DMF is suppressed. On the other hand, since the degree of the polyurethane resin is adjusted to a range of 10 to 30% by weight, the solidification rate becomes slow. As is apparent from the above, the amount of water permeation into the polyurethane resin solution is small, and the regeneration of the polyurethane resin is thus slowly carried out 13 201109123. Further, the viscosity of the polyurethane resin solution was adjusted to be in the range of 3 to lOPa.s. As a result, in the coagulating liquid, the difference in viscosity between the side of the surface layer 2a which is first regenerated and the side of the film-formed substrate which is not completely regenerated is increased, so that the foaming 4 of the upper layer Ph is formed obliquely. Further, the desolvent from the DMF urethane resin solution, that is, the surface layer 2a, the foamed 4 and the microporous, and the surface layer 2 & microporous, foamed by DMF and water replacement. 4 and the microporous system are connected to each other in a mesh shape. Further, the polyurethane resin solution applied to the film-forming substrate is continuously guided in the coagulating liquid. At this time, the transport speed of the polyamine resin solution in the coagulating liquid is set to be in the range of 5 to 1 〇 m/min. This transfer speed is also faster than the conventional transfer speed (a range of about 1 to 2 m/min), as shown in Fig. 4(A), on the upper layer ph side, the travel of the foam 4 with respect to the film-forming substrate The direction (the direction of the arrow in the figure) is formed obliquely on the front side. In other words, the foaming 4 in the f-layer layer Ph is formed such that the hair-forming direction 'to the end of the surface layer 2a side and the end portion is the same as the thickness direction, that is, 'regenerated on the film-forming substrate. The poly S i is formed obliquely. In addition, as in 4th (8)

The figure does not 'foam 4', when viewed from the polyurethane 榭, J = direction section, 'line along the vertical side = rumors 'foam 4 in the upper layer; in the thickness direction, in the fixed direction of the heart... r is along the thickness; = oblique: externally formed 'on the polyurethane resin on the film-forming substrate formed by surface contact (four) surface Μ, silk forming foam 201109123 Π 〇 in the washing / drying step, will The polyurethane resin regenerated in the regeneration step is washed with a washing liquid such as water to remove DMF remaining in the polyurethane resin and dried. In the case of polyamine resin, dry, medium, this embodiment uses a cylindrical dryer having a heat source cylinder. The resin is dried by passing the polyamine g resin along the circumferential surface of the cylinder. The obtained carbamic acid g-form 2 was taken up in a roll shape. In the laminating step, it is used to bond the amine-based smear sheet 2 and the double-sided tape 7 which are formed by a wet coagulation method. 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, that is, the holding pad 10 is completed. Next, the effect and the like achieved by the holding mat 1 of the present embodiment will be described. In order to facilitate the understanding of the description, the foaming structure of the urethane sheet formed by the conventional wet coagulation method will be described. In the conventional wet coagulation method, the polyurethane resin solution applied to a film-forming substrate such as a PET film is solidified in a coagulating liquid such as water. Therefore, as shown in Fig. 5, in the urethane sheet 12 constituting the conventional holding mat 2, the surface layer 12a formed at the initial stage during wet coagulation is also on the inner side, and is formed across The amine phthalate sheet 12 is foamed 14 in a large amount throughout the thickness. This foaming 14 is smaller on the side of the holding surface Sh than the side of the back surface Sr, and is formed in the vertical direction along the thickness direction. ' 201109123 In addition, in the urethane sheet 12, adjacent to the holding surface sh, a section parallel to the holding surface Sh, a hole formed by the foaming 14 and a vertical line passing through the center of the hole, and adjacent The position of the back surface Sr where the cross section parallel to the back surface Sr intersects is located inside the hole formed by the same foam 14 on the cross section parallel to the back core. That is, as shown in Fig. 6(A), the holding surface Sh of the adjacent holding surface sh is spaced apart from the inside of the range of 50 to 100 #m (the position of the arrow 1), and the thickness direction of the amine phthalate sheet 12 The central position (the position of the arrow m) and the position of the inside of the back side of the adjacent back side Sr are 5 〇 to 100 " m degree (the position of the arrow η). In this case, as shown in Fig. 6(Β), on the 1-1 cross section adjacent to the holding surface Sh, the hole Ha of the center Ma is formed by the foaming 14. Similarly, in the cross section of the central portion in the thickness direction of the urethane sheet 12, the hole Hb of the center Mb is formed by the same foaming 14, and the η·η section adjacent to the back surface Sr is taken. The hole Hc of the center Mc is formed by the same foaming 14'. The center center of the hole Ha, the center Mb of the hole booklet, and the center Mc of the hole Hc are located at substantially aligned positions in the thickness direction. That is, the vertical line L passing through the center W of the hole Ha intersects with the n-n to the intersection point Q. Therefore, the intersection point Q is located inside the hole He. In the case of using such a urethane sheet 12, the holding mat 2 is used, and when the grinding process is performed, the grinding force is applied, and the 塾2〇 side is trapped due to the buffering of the guanidinium carbamate. When the sheet 12 is compressed, and the workpiece is uneven, that is, when the foaming is "uneven in the formation", it is applied to the unevenness portion of each density, and is applied to 16 201109123. The magnitude of the stress 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 and the entire region. In the object to be polished after the polishing, for example, the polishing margin between the outer edge portion and the central portion is different, and a phenomenon of so-called outer edge depression occurs. In other words, the object to be polished is held by the holding pad 2 (). The polishing process is performed to damage the flatness of the machined surface. As is apparent from the above, the conventional 塾20' cannot sufficiently satisfy the requirements of high-integration and defect-free base layer wiring or display of high-quality images, etc. Fpd The high-precision flatness required for the glass substrate. In contrast, in the present embodiment, the foam 4 of the urethane sheet 2 is fixed in the upper layer Ph with respect to the thickness direction. It is formed by uniform inclination, and is formed along the thickness direction in the lower layer pr. Therefore, in the case of wet solidification, even if the density of the aminocarboxylic acid (4) sheet 2 is uneven, it is subjected to grinding processing. The compression can still equalize the grinding force. It is considered that the shape of the two pairs of foaming 4 is at the position where the lower layer (4) is formed, and the position on the holding surface Sh side is shifted. That is, for the holding surface Sh In terms of the compressive force, it is considered that the plurality of foams 4 formed on the side of the lower layer are fully expanded and contracted, so that the stress applied to the object to be polished can be reduced without significantly increasing the density unevenness. By increasing the flatness accuracy of the holding surface to equalize the stress on the object to be polished, the in-plane uniformity of the object to be polished can be improved, and the smoothness can be improved. Further, the foaming 4 is from the upper portion. Layer Ph across the lower layer p 17 201109123 When the body is formed obliquely, the holding pad itself is deformed in a rhombic shape due to the compressive force during the polishing process, and it is difficult to equalize the stress applied to the object to be polished. In the case where the fixed direction is formed by uniformly tilting, but is formed by random tilting, even if the lower layer Pr' having a larger enlargement tends to increase the stress unevenness, it is relatively the same as in the present embodiment. Since the bubble 4 is formed to be uniformly inclined in a fixed direction, stress unevenness can be reduced, and the flatness of the object to be polished can be improved. Further, in the present embodiment, in the foam 4, the connection center M1 and The line segment of the vertex M2 is a right-angled triangle of the hypotenuse, and the elevation angle θ when the vertex M2 is observed from the center M1 is in the range of 30 to 60 degrees, that is, the foaming is formed in such a manner that tan0 is in the range of 0.58 to 1.73. . Thereby, the regional compressive force against the holding surface sh is alleviated by the plurality of foams 4 formed close to the lower layer pr side, so that the stress unevenness to the workpiece can be surely reduced. When considering the in-plane uniformity of the object to be polished, the elevation angle Θ is in the range of 40 to 55 degrees, that is, it is preferable to form the foam 4 in such a manner that tan0 can be in the range of 〇84 to 1 μ. . Further, in the present embodiment, the foaming 4 is formed such that the pore diameter of the lower layer Pr is larger than the pore diameter of the upper layer Ph. Thereby, when the polishing process is performed and the polishing pressure is applied, the cushioning property can be ensured. Further, since the foaming 4 is formed obliquely in the upper layer ph system, the polishing pressure applied to the object to be polished can be equalized, and the immersed state on the holding mat 10 side of the workpiece can be obtained. Thereby, the situation in which the pad 20 itself is ground can be suppressed in the case where the shackle itself is subjected to grinding when the sag becomes large. According to this, it is possible to improve the flatness of the object to be polished while ensuring the flatness of the surface Sh while ensuring the 201109123. What's more, 'usually in the grinding process, in order to improve the flatness of the holding surface, it takes a period of operation to adapt to the time. On the other hand, in the polishing process using the holding mat 20, since the flatness of the holding surface sh can be ensured, the operation adaptation time can be shortened and the production efficiency can be improved. Further, in the present embodiment, the urethane sheet 2 constituting the holding mat 2 is merely exemplified by a polyurethane resin. However, it is not subject to this limitation. A resin sheet may be provided, and the cushioning property required for the object to be polished or an appropriate hardness may be used as the holding mat 20. A polyurethane resin or a substituted polyurethane resin can be used as the resin sheet. When a cushioning property, a hardness, or the like is considered, a sheet having a foaming structure formed by a wet coagulation method may be used as a resin sheet. Further, in the present embodiment, the thickness ratio of the upper layer to the lower layer h is changed by changing the conditions in the wet coagulation method, for example, the concentration or temperature of the polyurethane resin solution, the transport speed in the coagulating liquid, and the like. In other words, the central portion of the urethane sheet 2 in the thickness direction can be changed in the range of ±1% by weight from the center of the thickness direction with respect to the entire thickness of the urethane phthalate sheet 2. When it is considered to ensure the cushioning property at the time of polishing processing or to reduce the stress unevenness to the workpiece, it is preferable to set the boundary between the upper layer Ph and the lower layer ρΓ in the thickness direction of the amino phthalate sheet 2 Central office. Further, in the present embodiment, a double-sided tape 7' having a PET film as a substrate and having an adhesive layer formed on both surfaces of the substrate is exemplified, but the present invention is not limited to a substrate or an adhesive. material. 201109123 Quality. In the case of the holding mat, it is only necessary to have the urethane sheet 2, i.e., it is possible to apply only various adhesives to the back side Sr of the urethane sheet 2 instead of the double-sided tape 7. Further, in the present embodiment, the base material of the double-sided tape 7 is also exemplified as the base material for holding the crucible 10, but the present invention is not limited thereto, and may be formed on the urethane sheet 2 and The double-sided tape 7 is fitted with other support materials. The support material is not particularly limited, and examples thereof include a film made of PET or a non-woven fabric. Further, specific examples of the solvent, the film-forming substrate, and the coagulating liquid of the polyurethane resin solution are exemplified, but the present invention is not limited thereto, and other commonly used materials may be used. Further, although not particularly mentioned in the present embodiment, when the thickness unevenness of the amino phthalate sheet 2 formed by the wet coagulation method becomes large, the holding surface Sh and the back surface Sr may be parallel. It is preferable to smooth the back Sr side by polishing or cutting in advance. In this way, the flatness of the holding surface Sh can be further improved. Next, an embodiment in which the 塾 1 塾 is produced according to the present embodiment will be described. Also, it is described as a comparative example produced for comparison. Example 1 In Example 1, in the preparation of the amino phthalate sheet 2, a polyamine vinegar of MDI (methylene dipheny 1 diisocyanate, diphenyl sulfonium diisocyanate) was used. The resin was prepared by dissolving 10 parts of a solution dissolved in a ratio of 20% by weight in dmf, mixing 45 parts of DMF' and adding carbon black as a pigment. / 〇 DMF dispersion 40 parts ' to prepare a polyurethane resin solution. The viscosity of the obtained polyamine vinegar resin solution was 3.4 Pa.s. This viscosity was measured by a rotary spinner of 201109123 (manufactured by Toki Sangyo Co., Ltd., TVB_1〇) and a rotator of N.M3. (Measured value in the temperature environment of :: When the polyamine-based resin solution is applied, the gap of the coating device is set to 1.0 mm. After coating the polyurethane resin solution on the film-forming substrate of the PET film, continuously The temperature 2 (rc water (coagulating liquid) is guided. At this time, the transport speed (linear velocity) of the polyurethane resin solution is set to 7 in/min, and the polyurethane resin is completely regenerated. After washing/drying, it is obtained. The back of the urethane sheet 2

The Sr side is subjected to calendering to adhere the double-sided tape 7 to the polishing surface to complete the manufacture of the holding mat 10. [Example 2] In Example 2, a urethane sheet 2 was produced under the same conditions as in Example 除 except that the linear velocity of the polyurethane resin solution was set to 5 m/min, and the pad 1 was completed. Manufacturing. The viscosity of the polyurethane resin solution used was 32 Pas. Comparative Example 1 In Comparative Example 1 of the stomach, except that the polyester MDI urethane resin was dissolved in DMF at a ratio of 30% by weight, and the linear velocity in the coagulating liquid was set to 1.5 m/min, the other examples and examples 丨The same condition is used as the urethane sheet 12, and the production of the crucible is completed. The viscosity of the polyurethane resin solution was 8.2 Pas. That is, the holding mat 20 of Comparative Example 1 is a conventional holding mat (see also Fig. 5). The urethane sheets of the obtained Example 1 and Comparative Example 1 were visualized by a ternary amount side X-ray computed tomography apparatus to visualize the internal structure, thereby comparing the formation state of foaming. That is, using a three-dimensional side-side x-ray computed tomography apparatus ^ 21 201109123, manufactured by Takusho Co., Ltd., TDM1000_IS/SP), a continuous fault of 10 intervals from the holding surface Sh: "two: (In the comparative example i, the layer image 'is solved by the SEM image, and the cold is said" (〇lymPus §〇ft-Imaging S〇luti〇ns) Refers to foaming 14. Below, let η, ,, ^ ', Υ also ask.), not taking the foaming heart of each cross-sectional image). Next, the distance between the cross-sectional image observed from the apex Μ2 of the foaming 4 and the holding surface Sh, and the distance between the cross-sectional image of the hole having the center M1 and the holding surface from the center in the thickness direction, obtain a distance y between the cross-sections. Further, when the intersection of the straight line passing through the center M1 and the direction orthogonal to the thickness direction and the straight line passing through the thickness direction of the vertex M2 is p, the distance between the center Μι and the intersection point P is x (see also Fig. 3) ). The value of tan0 was obtained from the values of the distance X and the distance y obtained, and was 0.93 and L28 in Example 1 and Example 2, respectively, and 9.51 in Comparative Example J. Since the value of tang obtained is converted to the elevation angle 0 of the tilt angle of the foaming, the degree and the degree are 52 degrees in the first embodiment and the second embodiment, respectively, and the comparative example 1 is 84 degrees. The foaming of 1 and Example 2 was more inclined than the foaming of Comparative Example. As a result of measuring the tan Θ of the continuous tomographic image analysis, it was confirmed that the amino phthalate sheet 12 of Comparative Example 1 was foamed in the thickness direction as a whole across the thickness (see also Fig. 6). ). That is, from the center of the thickness direction to the surface layer side, although a state of being slightly inclined is observed, the direction in which the foam is formed is formed substantially along the thickness direction. On the other hand, in the urethane sheet 2 of Example 1, it was confirmed that the foam formation direction of the upper layer Ph was more inclined than that of Comparative Example 1 by 2011-09-123 (see also Fig. 2). For 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 mats of the respective Examples and Comparative Examples, and the industrial specifications (JIS B 0601) were used. : ' 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 (manufactured by Tokyo Seimi Co., Ltd., surfcom 480A) was used and measured according to the following measurement conditions. The width W between the adjacent convex portion (mountain portion) and the convex portion and the height S between the convex portion and the concave portion (valley portion) are calculated from the measurement curve obtained by the unevenness on the surface of the substrate, and the width W is calculated. On the horizontal axis, the height S is a 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 smaller the height S. Therefore, the flatness is more excellent when the slope a is smaller. Grinding conditions using a grinder: OSCAR grinder (SP-DFAM, SP-1200) Grinding speed (number of revolutions): 61 rpm Processing pressure: 100 g/cm2 Grinding slurry: grouting time: 30 min Corrugation center undulation measurement condition Evaluation length: 90 mm Measurement speed: 3.0 mm/s Interruption value: 0.8 to 8.0 mm r 23 201109123 Film type: 2RC Measurement range: ±40.0 in m Tilt compensation: smooth curve was compared using the holding mats of Example 丨 and Example 2, respectively. The flatness a after polishing with the holding mat 20 of Comparative Example 1 shows that the tangent a of Example i and Example 2 is represented by 0.0004 and 〇.6, respectively, after polishing for 30 minutes, and is compared. The example flatness a is represented by 0.0012. That is, in the case of the embodiment and the embodiment 2, the final flatness a can be improved as compared with (4). Therefore, it is clear that the use is formed by the wet solidification method in which the upper layer Ph is uniformly inclined in the fixed direction with respect to the thickness direction, and the lower layer pr is formed along the thickness direction. The formed pad 4 of the foamed urethane sheet 2 can improve the flatness accuracy of the holding surface and at the same time improve the in-plane uniformity of the object to be polished. The present invention provides a holding mat which can improve the flatness accuracy of the holding surface and improve the in-plane uniformity of the object to be polished, and thus contributes to the manufacture and sale of the holding mat, and is an industrially useful invention. . BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view showing a holding mat suitable for use in an embodiment of the present invention; and Fig. 2 is a view showing a state of foam formation in a urethane sheet constituting the holding mat of the embodiment. 2(A) 24 201109123 is a cross-sectional view in the thickness direction of the urethane sheet, and the second (B) diagram is shown in the °a_a section in the second (A) diagram, A schematic explanatory view of the positional relationship of the center of the hole formed in the bb section and the c_c section; Fig. 3 is a view showing the degree of inclination in the foam formed on the urethane sheet constituting the holding mat of the embodiment; Fig. 4 is a cross-sectional scanning electron micrograph showing a holding mat of the embodiment, wherein the fourth (A) diagram shows a section in the thickness direction along the longitudinal direction at the time of wet film formation, and the fourth (4) B) the figure shows a section in the thickness direction along the width direction intersecting the length direction; FIG. 5 is a schematic view showing a conventional section of the holding ;;

Fig. 6 is a view showing a state in which foaming is formed in a urethane sheet which constitutes a conventional holding mat, wherein Fig. 6(a) is a cross-sectional view in the thickness direction of the aminophthalic acid sheet. Further, Fig. 6(B) is a schematic explanatory view showing the positional relationship of the centers of the holes formed in the M section, the mm section, and the η·η section in Fig. 6(A). [Description of main component symbols] 2. 12. Amino acid vinegar flakes; 2a, 12a: surface layer; 4, 14: foaming; 7: double-sided tape; 8: release paper; 25 201109123 10, 20: holding pad;

Ha, Hb, He: 孑L;

Lc: distance;

Ml, Ma, Mb, Me: center; M2: vertex;

Pr : lower layer;

Ph: upper layer; Q: intersection point;

Sh : keep the face;

Sr: back; and 0: elevation angle. 26

Claims (1)

201109123 VII. Patent application scope: 1. A holding mat, which contains ····························································· a plurality of pieces of the large upright type of the king body; at least one of the foaming of the enamel, from the resin, a solid f-square = foam forming direction, consistent with the thickness direction along the U 疋 direction The ground is formed by tilting. 2. The switch according to the item 1, wherein the central portion of the tree direction is in a range of ±10% from the center of the thickness direction with respect to the total thickness of the two. 3. The holding mat of claim 2, wherein the hair is wrapped from the central portion of the thickness direction to one of the back ends of the holding surface The pore diameter of the foamed end portion of the surface is large. 4. The holding mat according to claim 3, wherein the hair f is from the central portion in the thickness direction to the foamed end portion of the back surface of the holding surface form. The thickness of the holding pad according to the fourth aspect of the invention, wherein the foaming is adjacent to the holding surface, a vertical line passing through a center of the hole formed on the surface parallel to the holding surface, and adjacent The position at which the cross section parallel to the back surface intersects on the back surface, r ^ , 27 201109123 is set to be on the outer side of at least one of the holes formed by the foaming on the cross section parallel to the back surface. The retaining crucible according to claim 4, wherein the foam is formed in a center of the thickness direction in a direction parallel to the retaining surface, and a center M1 of the hole and a vertex of the retaining surface side The connecting line segment formed by M2 is a right-angled triangle of the oblique side. When the elevation angle of the vertex M 2 is 0 from the center Μ1, the elevation angle 0 is set in the range of 30 degrees to 60 degrees. The holding mat according to the item, wherein the resin sheet is a long sheet formed by a wet coagulation method; and the foaming end of the foam from the central portion to the holding surface side in the thickness direction Foam formation direction A retaining pad according to the length direction of the resin sheet, wherein the foaming system is in the width direction intersecting the length direction. The retaining pad according to the eighth aspect of the invention, wherein the foaming is formed in a vertical direction from a cross-sectional view in the width direction intersecting the longitudinal direction. The holding mat of the seventh aspect of the invention, wherein the resin sheet is made of a polyurethane resin; and the foaming gap is formed into a microporous shape.