JP2010050277A - Polishing pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a desirable polishing pad when the notch part of a semiconductor wafer is mirror-polished. <P>SOLUTION: A polishing pad for polishing a notch part has an apical end shaped like a convex form modelling after a special concave form of the notch part, each part of the apical end gets in contact exclusively with a portion corresponding to the notch part, and never contacts other parts. For this reason, each corresponding part of the polishing pad is provided with such a different desirable characteristic, thereby making available a desirable polishing pad. For example, a polishing pad may include multilayer polishing pad members on which flexibly deformable polishing pad members and polishing pad members excellent in a withstand load nature are laminated, wherein the characteristic of each layer's exposed part (apical part) can be effectively utilized. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polishing pad used in a semiconductor wafer polishing apparatus for polishing an inner surface of a notch portion of a semiconductor wafer and a method for manufacturing the same.

  In general, the semiconductor wafer 20 is provided with a notch 22 which is a V-shaped notch as shown in FIG. 4 in a part of the outer peripheral portion due to its direction specificity, and the semiconductor wafer 20 is formed using the notch 22. Are aligned and oriented. The notch 22 can be formed using, for example, a spindle-shaped grindstone. The shape of such a notch is specified in SEMI M1-0707, and specifically has a shape as shown in FIG. For example, a V-shaped notch opened at 90 ° on the outer peripheral portion of the semiconductor wafer 20 having a diameter of 300 mm is formed so that the depth D is 1 mm and a pin having a diameter of 3 mm is inserted to fix the position. Polishing of the inner surface of the V-shaped notch (for example, the inner surface 24 in FIG. 1) cannot be performed by a normal semiconductor wafer polishing apparatus.

  Therefore, for example, polishing of the inner surface is performed using an apparatus as shown in FIG. 8 (Patent Document 1). The notch polishing apparatus 901 includes a table 903 that holds the wafer W, and a pulse motor 902 that can rotate and pulsate the table 903 in the forward and reverse directions. Among these, a vacuum suction device (not shown) is connected to the table 903 so that the wafer W can be held on the table 903 by vacuum suction.

  Further, the notch polishing apparatus 901 has a rotating buff 904, and the rotating buff 904 is formed of an elastic material, for example, a synthetic resin such as polyurethane foam. The rotation buff 904 is connected to an electric motor (first motor) 905 that rotates the rotation buff 904 and is held by a link mechanism 906. The rotation buff 904 is rotatable about an axis parallel to the wafer surface held by the table 903.

  The link mechanism 906 includes links 961 and 962. The front end side of the substrate 961a of the link 961 is bifurcated, one of the branch portions is held by a bearing 907, and the other is connected to a pulse motor (second motor) 908. Here, the center axis of the bearing 907 and the rotation axis of the pulse motor 908 are on the same straight line, and the line connecting the centers is parallel to the wafer surface and substantially in contact with the notch portion 932 of the wafer W. ing. In addition, brackets 961b and 961b are erected at an intermediate portion of the substrate 961a of the link 961, and a link 962 is attached to the brackets 961b and 961b so that a seesaw operation can be performed around the shaft 962a. A rotary buff 904 and an electric motor 905 are attached to one end of the link 962. On the other hand, an air cylinder device 909 is installed between the other end of the link 962 and the rear end of the link 961. In other words, the air cylinder device 909 is installed such that the cylinder base end is fixed to the link 961 and the rod tip rotates around the link 962 to make a pair. The air cylinder device 909 causes the link 962 to be separated from the link 961. It can be operated separately. The air cylinder device 909 is connected to an air supply / discharge device and an air pressure adjustment device (not shown).

  First, the wafer W is set on the table 903 by vacuum suction or the like. By setting the wafer W, the link mechanism is set so that the vicinity of the notch portion 932 of the wafer W is positioned on a line connecting the center axis of the bearing 907 and the rotation axis of the pulse motor 908. For this purpose, the positional relationship between the table 903, the bearing 907, and the pulse motor 908 is set in advance in consideration of the diameter of the wafer W that is the object to be polished, or the bearing 907 and the pulse with respect to the table 903 are set. It is desirable to allow the motor 908 to move relatively. When the wafer W is set, the rotary buff 904 is separated from the wafer W by the air cylinder device 909.

  Next, the air cylinder device 909 is operated to press the rotating buff 904 against the inner surface of the notch portion 932 of the wafer W. Then, the peripheral surface portion of the rotating buff 904 is elastically deformed, and the rotating buff 904 comes into wide contact with the wafer W. Thereafter, the electric motor 905 rotates the rotary buff 904, and the pulse motor 908 causes the rotary buff 904 to move along the bulging portion of the inner surface of the notch portion so that the pressing force acts in a direction perpendicular to the inner surface of the notch portion. Turn slowly. At this time, for example, an abrasive in which colloidal silica is dispersed in an alkaline solution is supplied to the notch portion 932. This turning polishing operation is performed a predetermined number of times in a reciprocating manner along the inner surface of the notch portion. Further, if necessary, the table 903 is rotationally pulsated in the forward and reverse directions perpendicular to the pressing direction of the rotary buff 904, and the entire inner surface of the notch 932 is polished.

By the way, even in such an apparatus, there is a problem that burrs or the like are generated in the notch portion, and an improved chamfering of the semiconductor wafer that can efficiently polish all the chamfered surfaces including the notch portion of the semiconductor wafer. A surface polishing apparatus has been proposed (for example, Patent Document 2).
Japanese Patent No. 2798345 JP 2000-317790 A

  However, due to the complicated shape of the notch portion, it is difficult for the entire surface of the polishing pad to contact the inner surface of the notch portion under uniform conditions, and it is difficult to prevent the occurrence of burrs and the like of the polishing pad. It is also difficult to prevent uneven wear of the wear pad. Although it is conceivable to use a polishing pad with a low wear rate, a polishing pad that does not wear may cause the quality of the surface to be polished to deteriorate.

  In view of the above-mentioned problems, the inventors have intensively studied the characteristics of a polishing pad that is preferable for polishing the inner surface of the notch portion and the like, and have made the present invention. That is, as it advances along the inner surface from the outer periphery, the inner surface is sharply bent at the back of the notch, and the direction changes by about 90 ° with a predetermined curvature (or radius of curvature r), and the inner surface becomes flat again. Since it is connected to the outer periphery on the opposite side, the contact state between the inner surface and the polishing pad at the back, the contact state between the inner surface near the outer periphery and the polishing pad, and the so-called corner and polishing pad near the outer periphery These contact states are different from each other. For example, in the above-mentioned inner part, it is considered that the characteristic of flexibly deforming and contacting the inner surface corresponding to the rapidly changing curvature radius r is preferable. Therefore, it is considered preferable to have excellent load resistance. On the other hand, the polishing pad that polishes the notch has a tip that has a convex shape that follows the special concave shape of the notch, and each part of the tip is in contact with the corresponding part of the notch. However, there is little contact with other parts. Therefore, it is possible to provide a more preferable polishing pad if each portion of the corresponding polishing pad can have such different preferable characteristics. For example, if the polishing pad includes a multilayer polishing pad member in which a polishing pad member that can be flexibly deformed and a polishing pad member having excellent load resistance are laminated, these characteristics are utilized in the exposed portion (tip portion) of each layer. Can do. And it is possible to configure the polishing pad so that the tip of the convex portion can be flexibly deformed, and the so-called corner portion of the notch portion comes into contact with the polishing pad member having excellent load resistance, This can be realized by a layer structure. More specifically, the following can be provided.

(1) A polishing pad for polishing a notch portion formed on a peripheral edge of a semiconductor wafer, comprising a tip portion that contacts an inner surface of the notch portion, the tip portion being a convex shape that follows the notch shape of the notch portion It is possible to provide a polishing pad comprising a multilayer pad member that is laminated so that first and second pad members having different physical properties are exposed at the tip of the convex shape.

  Here, the shape of the notch portion includes a shape defined by SEMI, but may further include a similar concave shape. That is, the notch portion may include a concave recess formed on the periphery of the semiconductor wafer. At least a part of the polishing pad (for example, a tip end portion) can enter the inside of the notch portion (for example, a portion sandwiched between both V-shaped oblique lines composed of two oblique lines). The notch shape generally means a V-shaped or U-shaped cut or groove shape. The convex shape that follows the notch shape may include a shape that fits into the notch portion and a shape similar thereto. For example, in the internal polishing of a V-shaped notch, if the V-shaped opening angle is 45 degrees, it is preferable to have a tip angle slightly smaller than that. The polishing pad is provided, for example, with a peripheral edge sharpened at the periphery (outer periphery) of the disk. The disk-shaped (or donut-shaped) polishing pad is rotated and arranged so as to be orthogonal to the disk-shaped semiconductor wafer, and the polishing pad disposed on the outer periphery of the disk is inside the notch portion on the outer periphery of the wafer. Intrusion is also included in the fitting. Each of the first and second pad members spreads flatly and is stacked. Lamination is performed by superimposing layers substantially parallel to the convex shape, so that the end of each layer is exposed and striped at the end of the laminate. Since it is substantially parallel to the convex shape, the end portion of each layer is exposed at the tip portion to exhibit a stripe shape. In particular, the first pad member may be a polishing pad member that can be flexibly deformed, and in the convex shape that follows the notch shape, the end of the layer may be exposed (appear) at the central protrusion. In this way, the protrusion may be able to contact the notch-shaped bottom. The second pad member may be a polishing pad member having excellent load resistance, and may be disposed on both sides of the first pad member, and the first pad member may be sandwiched. The second pad member may be disposed on both sides of the first pad member, which is a convex protrusion at the center of the convex shape, to form a convex ridge portion.

(2) The polishing pad according to (1) above, wherein the different physical properties are different hardnesses.

  Here, the hardness is closely related to the compressibility and may be defined in relation to each other. The hardness is measured according to, for example, JIS K6253. Six polishing layers sliced to a thickness of 1.27 mm are cut out at 1.5 cm square. The cut samples are held at 23.5 ° ± 2 ° C. × humidity 50% × 24 hours, and then 6 samples are stacked and set on a SHORE A hardness meter. After piercing a sample in which six needles of the A hardness meter were stacked, the A hardness meter pointer after 1 minute was read.

The compression rate is measured according to JIS L1096. Using a cylindrical indenter with a diameter of 5 mm for the foam polishing layer (sample size diameter 7 mm), a load is applied at 25 ° C. with TMA manufactured by Mac Science, and T1 (μm) and T2 (μm) are measured. .
Compression rate (%) = [(T1-T2) / T1] × 100
Here, T1 represents the sheet thickness when a stress load of 30 kPa (300 g / cm ² ) is held for 60 seconds from the no-load state, and T2 is when a stress load of 180 kPa is held for 60 seconds from the T1 state. The thickness of the sheet is shown.

  The hardness of the polishing pad member having excellent load resistance by the above method is preferably 70 or more, and more preferably 80 or more. However, if the hardness is too high, the polished surface tends to be rough, preferably 100 or less, more preferably 95 or less. On the other hand, the hardness of the polishing pad member excellent in flexibility is preferably 65 or more, and more preferably 75 or more. However, if the hardness is too high, the flexibility is deteriorated. Therefore, the hardness is preferably 95 or less, and more preferably 90 or less. It is preferable that the polishing pad member having excellent load resistance has a hardness of 5 or more higher than that of the polishing pad member having excellent flexibility.

  Considering the compression rate, the compression rate by the above method of the polishing pad member having excellent load resistance is preferably 10.0% or less, more preferably 8.0% or less, and even more preferably 5.0% or less. . However, if the compression rate is too high, the polished surface tends to be rough, preferably 0.5% or more, more preferably 1.5% or more, and still more preferably 2.0% or more. On the other hand, the compressibility of the polishing pad member having excellent flexibility is preferably 12.0% or less, more preferably 11.0% or less, and still more preferably 10.0% or less. However, if the compression ratio is too high, the flexibility is deteriorated, so that it is preferably 1.0% or more, more preferably 3.0% or more, and further preferably 5.0% or more. This compression rate is closely related to the hardness, but for the present invention, the definition of hardness prevails.

(3) The polishing pad according to the above (1) or (2), wherein the first pad member and the second pad member are bonded together by thermal welding with an adhesive or a thermoplastic resin. Can be provided.

  The first pad member and the second pad member to be laminated can be bonded to each other by thermal compression, but preferably can be heat-welded with a resin-based adhesive such as urethane or a thermoplastic resin. The polishing pad may not be a multilayer member made by laminating thin layer members. The first pad member is exposed where the surface contacting the inner surface of the V-shaped notch and the material combination in the vicinity of the surface contact with the inner surface of the V-shaped notch, and from the inner surface of the V-shaped notch in the polishing process. What is necessary is just to arrange | position so that a 2nd pad member may be exposed in the place contact | abutted to the notch edge corner | angular part which may go out. In other words, it is difficult to apply a high contact pressure when contacting the back of the V-shape, and the portion that contacts the notch edge corner is likely to receive a high surface pressure locally. At the end of the body, the end of each layer is exposed and striped. Since it is substantially parallel to the convex shape, the end portion of each layer is exposed at the tip portion to exhibit a stripe shape. In particular, the first pad member may be a polishing pad member that can be flexibly deformed, and in the convex shape that follows the notch shape, the end of the layer may be exposed (appear) at the central protrusion.

(4) The polishing pad according to any one of (1) to (3), wherein the first pad member is made of a resin-containing nonwoven fabric, and the second pad member is made of foamable urethane. Can be provided.

  The non-woven fabric of the resin-containing non-woven fabric is a fiber sheet, web or vat, in which the fibers are oriented in one direction or randomly, alternating current (that is, the fibers cannot be separated from each other), and / or fusion, And / or fiber-bonded fibers may be included. Paper, woven fabric, knitted fabric, tufts and shrunk felt are excluded. For example, polyester nonwoven fabric, nylon nonwoven fabric, acrylic nonwoven fabric, and the like may be included, and the resin contained in such a nonwoven fabric may include urethane resin, polyethylene resin, and the like. Generally, a nonwoven fabric is manufactured by a spun bond, a thermal bond, a chemical bond, a needle punch, a stitch bond, a wet method, a spunlace method (a hydroentanglement method), a melt blow method, or the like. In the present invention, a wet method capable of arbitrarily changing the basis weight (mass per unit area) with a uniform thickness is preferable.

  Here, foamed urethane forms bubbles inside, and hardness, compressibility, density, and the like differ when the size of the bubbles is changed. In general, polyurethane foam is hard, and those having a hardness standard of 60 to 100 in Shore A standard can be used. As such foamed urethane, a polyurethane resin can be used. This polyurethane resin comprises an isocyanate-terminated urethane prepolymer and an organic diamine compound, and the isocyanate-terminated urethane prepolymer comprises a polyisocyanate, a high molecular polyol and a low molecular polyol. Examples of polyisocyanates include 2,4- and / or 2,6-diisocyanatotoluene, 2,2'-, 2,4'- and / or 4,4'-diisocyanatodiphenylmethane, 1,5 Naphthalene diisocyanate, p- and m-phenylene diisocyanate, dimeryl diisocyanate, xylylene diisocyanate, diphenyl-4,4'-diisocyanate, 1,3- And 1,4-tetramethylxylidene diisocyanate, tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate, 1-isocyanato-3-isocyanate Natomethyl-3,5,5-trimethylcyclohexane (= isophorone diisocyanate), bis- (4 -Isocyanatocyclohexyl) methane (= hydrogenated MDI), 2- and 4-isocyanatocyclohexyl-2'-isocyanatocyclohexylmethane, 1,3- and 1,4-bis- (isocyanatomethyl) -cyclohexane, bis -(4-isocyanato-3-methylcyclohexyl) methane, and the like. Examples of the polymer polyol include hydroxy-terminated polyesters, polycarbonates, polyester carbonates, polyethers, polyether carbonates, polyester amides, etc. Polyethers and polycarbonates having good hydrolyzability are preferred, and polyethers are particularly preferred from the viewpoint of cost and melt viscosity. Polyether polyols include reaction products of starting compounds having reactive hydrogen atoms with alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, epichlorohydrin or mixtures of these alkylene oxides. Is mentioned. Starting compounds having reactive hydrogen atoms include water, bisphenol A and the divalent alcohols described above to produce polyester polyols.

(5) The polishing pad according to any one of (1) to (4) above, wherein the thickness of the first pad member is thinner than the circumferential width of the notch portion. it can.

  The first pad member is positioned at the forefront of the polishing pad, and it is desired that the first pad member be flexibly deformed and contacted with a small radius of curvature r at the back of the notch portion. However, the first pad member has low resistance to high surface pressure. There are many. If the thickness of the first pad member is thinner than the circumferential width of the notch portion, the first pad member can be prevented from hitting a so-called corner portion of the outer peripheral portion. However, when the width of the notch portion is equal to or thicker than the circumferential width, this corner portion is not preferable because it abuts against the first pad member. In addition, a laminated pad member can be manufactured by stacking the second pad member made of foamable urethane with the adhesive interposed in the first pad member made of the resin-containing nonwoven fabric and heating and compressing. If this is used, the notch can be satisfactorily polished as described above. In addition, lamination | stacking is performed in order of a 2nd pad member, an adhesive agent, a 1st pad member, an adhesive agent, and a 2nd pad member about an annular flat pad member, respectively, and heat-compresses. A convex shape is formed on the outer side in the radial direction so that the first pad member protrudes at the outer peripheral portion.

  According to the present invention, it is possible to greatly improve the chamfering quality of the notch portion by making the structure of the polishing pad used for polishing the notch portion of the semiconductor wafer a multilayer structure (consisting of two or more layers). it can. This multilayer structure can be configured by laminating each layer in parallel to the processing direction. More specifically, the processing surface of the semiconductor wafer can be processed evenly by configuring the polishing pad material or physical properties used for mirror processing of the notch portion of the semiconductor wafer from a plurality of different members. . In addition, by using a urethane-based resin that is unlikely to generate burrs at locations where burrs are likely to occur, it is possible to suppress burrs of the polishing pad that are likely to occur due to notch processing, and therefore, over-polishing is unlikely to occur. . Moreover, a polishing pad can be easily manufactured by using resin materials such as nonwoven fabric and urethane as the material of the polishing pad. Furthermore, since it becomes the above-mentioned structure, generation | occurrence | production of the polishing nonuniformity of a notch part can be suppressed, and the processable life of a polishing pad can be extended. And generation | occurrence | production of the burr | flash of a polishing pad can be restrict | limited.

  Next, embodiments of the present invention will be described with reference to the drawings. In the drawings, components having the same configuration or function and corresponding parts are denoted by the same reference numerals, and description thereof is omitted. Moreover, in the following description, only an example of the embodiment according to the present invention is shown, and can be appropriately changed without exceeding the scope of the present invention based on the common general knowledge of those skilled in the art. Therefore, the scope of the present invention is not limited to these specific examples. Also, these drawings are emphasized for the purpose of explanation, and may differ from actual dimensions.

  FIG. 1 shows a state in which a polishing ring 11 (see FIG. 3) including a polishing pad 10 according to an embodiment of the present invention is ready to mirror-polish an inner surface 24 of a notch portion 22 of a silicon wafer 20 which is a semiconductor wafer. Show. The polishing pad 10 has a multilayer structure in which a urethane member 14 made of foamable urethane is disposed on both sides of a nonwoven fabric member 12 made of a nonwoven fabric impregnated with a resin, with a boundary 15 interposed therebetween. This polishing pad 10 moves the polishing ring 11 (see FIG. 3) provided on the outer periphery thereof in the left direction in the drawing and presses it against the inner surface 24 of the notch portion 22 of the silicon wafer 20 in the direction of the downward arrow in the drawing. It can be rotated and polished. The polishing ring can be moved (oscillated) in the left-right direction in the drawing by a mechanism (not shown), and the corresponding parts of the polishing pad 10 can be pressed against each part of the inner surface 24 of the notch portion 22 with an appropriate pressure. The main surface of the silicon wafer 20 and the vicinity 26 and 28 of the notch 22 may be affected by the polishing by the polishing pad 10. Details will be described later.

FIG. 2 shows a cross-sectional view of the polishing pad 10. The central layer is made of the nonwoven fabric member 12 and the layers on both sides thereof are made of the urethane member 14. The adhesive layer is applied between the two layers 15 and thermally bonded to adhere to each other. More specifically, the nonwoven fabric member 12 is a urethane impregnated nonwoven fabric (model number: NF7055) manufactured by Toray Cortex Co., Ltd., and the urethane member 14 is a urethane foam (model number: PV2700) manufactured by Chiyoda Corporation. The adhesive is polyamide (hot melt adhesive) manufactured by Toyobo Co., Ltd. These were bonded by compression at 125 ° C. and 1.3 Kg / cm ² . As shown in FIG. 3, the polishing pad 10 is disposed on the outer periphery of the polishing ring 11, and the entire polishing pad 10 has an annular shape. If the cross section of the polishing pad is taken on a plane perpendicular to the plane defined by the annular shape, the tip (outer periphery) has a wedge shape, and the wedge shaped tip has an arc of radius R in the cross section. Form. This radius R is larger than the curvature radius r of the back portion 27 of the notch portion 22, and the tip portion of the polishing pad 10 is deformed by pressing, so that the inner surface of the back portion 27 is contacted and the surface is mirror-polished. Can do. As can be seen from FIG. 1, the thickness of the layer made of the nonwoven fabric member 12 is thinner than the width in the outer peripheral direction of the notch portion 22, and the nonwoven fabric member 12 of the polishing pad 10 is always positioned inside the notch portion 22 during polishing. However, it does not contact the corner 25 at the boundary between the inner surface 24 and the outer periphery. Since the contact area of the corner portion 25 tends to be small, when it comes into contact with the polishing pad 10, the corner portion 25 tends to have a high surface pressure locally. The nonwoven fabric member 12 does not come into contact with the corner portions 25, but comes in contact with a harder and higher load bearing urethane member 14. Therefore, the polishing pad 10 of this embodiment can cope with the mirror polishing of the back portion 27 of the notch portion 22 and the corner portion 25.

  Here, the urethane-impregnated nonwoven fabric used for the nonwoven fabric member 12 was 84 on average as measured by a SHORE A hardness meter. The compression rate was 3.7%. On the other hand, the hardness of the urethane foam of the urethane member 14 was 92 on average. The compression rate was 0.91%. Therefore, the difference in hardness was 8.

  FIG. 6 shows how the notch 22 is mirror-polished by the polishing pad 10 of this embodiment. (A) shows the place where the center of the curved surface of the back part 27 of the notch part 22 and the center of the front-end | tip part of the polishing pad 10 are located in a line and are ready for grinding | polishing as shown with a dashed-dotted line. (B) shows a state in which the polishing pad 10 is pressed against the notch 22 by a mechanism (not shown). This mechanism can swing the polishing pad 10 left and right in the figure as indicated by the arrows. As a result, the vicinity of the tip portion R of the polishing pad 10 is flexibly deformed, and the curved surface of the back portion 27 of the notch portion 22 is mirror-polished. However, the corner portion 25 does not contact the nonwoven fabric member 12. (C) further shows a state in which the polishing pad 10 is strongly pressed by either the left or right of the inner surface 24 of the notch 22 (upper or lower in the drawing) as the semiconductor wafer 20 swings. Even in such a case, the corner portion 25 does not contact the non-woven fabric member 12 but contacts the urethane member 14, and thus can be sufficiently endured without being damaged even at a high surface pressure.

  FIG. 7 shows a comparative example in which the entire polishing pad 10 is formed of the nonwoven fabric member 12. (A) shows the place where the center of the curved surface of the back part 27 of the notch part 22 and the center of the front-end | tip part of the polishing pad 10 are located in a line and are ready for grinding | polishing as shown with a dashed-dotted line. (B) shows a state in which burrs 13 are generated on the surface of the tip of the polishing pad 10 as a result of polishing in this comparative example. The burr 13 is thought to have come out on the surface due to the nonwoven fabric fibers frayed, but when the polishing is continued relatively long, the main surface of the silicon wafer 20 shown in FIG. There is a risk that burrs will come into contact with the neighborhoods 26 and 28, and this place may be scratched.

  As described above, according to the invention of the present application, resins having different materials or physical properties are sandwiched in a sandwich shape, so that the inner surface of the notch portion is preferably mirror-polished. In particular, a pad made of a material such as foaming urethane has a long life, but the surface roughness by mirror polishing is rougher than that of a pad made of nonwoven fabric. On the other hand, when polishing with a pad made of non-woven fabric, burrs of the pad are likely to occur and the life is short. In particular, mirror polishing of the back (or bottom) of the notch is not sufficient with a pad made of a material such as foaming urethane, but the other inner surface of the notch is foamable if conditions are adjusted. Even a pad made of a material such as urethane can ensure sufficient quality. Therefore, if a non-woven fabric member made of non-woven fabric is applied to the back (or bottom) of the notch, and a urethane member made of foamable urethane is applied to the other, the usable life (life) is suppressed. Therefore, it becomes possible to obtain a high quality surface by polishing while suppressing over polishing and unevenness of the mirror surface. Moreover, if the nonwoven fabric member and the urethane member are bonded with an adhesive, peeling at the interface can be prevented, and a high-quality surface can be obtained by polishing while suppressing unevenness of the mirror surface.

It is a partially broken perspective view which shows the notch part of the polishing pad which is embodiment of this invention, and a silicon wafer in the state ready for mirror polishing. It is a fragmentary broken view which shows the cross section of the front-end | tip part of the polishing pad which is embodiment of this invention. It is a top view of a polishing ring provided with a polishing pad. It is a top view of a silicon wafer provided with a notch part. It is a schematic diagram which shows the notch shape based on SEMI M1-0707. It is a schematic diagram which shows a mode that the notch part of the polishing pad which is embodiment of this invention and a silicon wafer is mirror-polished. It is a schematic diagram which shows the state which is going to mirror-polish the polishing pad which consists only of a nonwoven fabric member, and the notch part of a silicon wafer as a comparative example, and the damaged state of the polishing pad after grinding | polishing. It is a perspective view which shows the example of the conventional grinding | polishing apparatus which grind | polishes a notch part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Polishing pad 11 Polishing ring 12 Nonwoven fabric member 14 Urethane member 20 Silicon wafer 22 Notch portion 24 Inner surface 25 Corner portion

Claims (5)

In a polishing pad for polishing a notch formed on the periphery of a semiconductor wafer,
A tip portion contacting the inner surface of the notch portion;
The tip portion includes a multi-layer pad member that has a convex shape that follows the notch shape of the notch portion and is laminated so that first and second pad members having different physical properties are exposed at the tip end of the convex shape. A polishing pad characterized by that.   The polishing pad according to claim 1, wherein the different physical properties are different hardnesses.   3. The polishing pad according to claim 1, wherein the first pad member and the second pad member are bonded to each other by heat welding using an adhesive or a thermoplastic resin.   The polishing pad according to any one of claims 1 to 3, wherein the first pad member is made of a resin-containing non-woven fabric, and the second pad member is made of foamable urethane.   5. The polishing pad according to claim 1, wherein a thickness of the first pad member is smaller than a circumferential width of the notch portion.

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