JP2006346798A - Polishing pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing pad improved in polishing rate and capable of reducing scratch. <P>SOLUTION: In this polishing pad 1 having a hole 4 opened in a polishing face 2 is provided with inclination in an edge part 5 of the opening of the hole 4 over the whole circumference. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polishing pad used for polishing an object to be polished such as a semiconductor substrate such as a silicon wafer, glass or an aluminum disk.

  Polishing pads used for precision polishing of semiconductor wafers include porous urethane pads that are manufactured by impregnating urethane resin into a non-woven fabric and wet coagulating, foamed polyurethane pads obtained by foaming urethane resin, and micro hollow spheres made of urethane resin. Hard polyurethane pads contained in are known. Porous urethane pads include SUBA series manufactured by Nita Haas, etc., independent foamed polyurethane pads include MH series manufactured by Nitta Haas, and hard urethane pads as IC series manufactured by Nitta Haas. Etc.

  In these polishing pads, groove processing and hole processing are performed to improve the polishing rate, to increase the holding performance of the polishing slurry during polishing processing, and to eliminate excessive polishing slurry in many cases. Has been made.

  Patent Document 1 is known as an example of a polishing pad subjected to hole machining. The polishing pad of Patent Document 1 includes a first region close to the outer periphery and a second region separated from the outer periphery, and the latter has a plurality of openings or larger average pores than the former. And The purpose is to improve the polishing uniformity of the substrate. Also, a laminated polishing pad in which an upper layer polishing pad provided with a plurality of slurry introduction through holes and a plurality of slurry supply through holes and a lower layer polishing pad provided with a slurry introduction part and a slurry passage groove are laminated. An example in which CMP (Chemical Mechanical Polishing) is used is known from Patent Document 2. In Patent Document 2, the object is to prevent the solidification of the slurry causing scratches and improve the in-plane uniformity of the workpiece. In addition, by providing multiple through holes in the polishing pad, it is easy to remove the workpiece after polishing, and even if the polishing pad is worn, it is compared with a pad that has been subjected to groove processing that has been conventionally known. In addition, Patent Document 3 also discloses an example in which the life of the pad is extended because the long hole is not lost, and as a result, the manufacturing cost can be reduced.

  As described above, several examples of drilling a polishing pad are known, but the shape of the hole is a through hole and the number and arrangement are shown, but those disclosed specifically with respect to the hole shape Is missing. Further, since the hole has a shape perpendicular to the polishing surface, when a polishing pad subjected to such hole processing is used in the polishing process of a semiconductor wafer or glass, the sharp edge portion covers the hole. There is a problem that scratches (polishing scratches) are likely to occur in the polished article.

  With regard to this scratch, the hole has a different problem from the groove. The groove is excellent in supplying and discharging the polishing slurry, so that polishing scraps are discharged together with the polishing slurry, the polishing rate is high to a certain extent, and there are few scratches, enabling a balanced surface treatment. is there.

However, since the holes are independent of each other unlike the grooves, a sufficient amount of polishing slurry can be secured. On the other hand, the polishing slurry once entering the holes is not easily discharged from the holes. Although the polishing rate is high due to the structure having a specific problem, there is a problem completely different from the groove that the scratch is larger than the groove.
US Pat. No. 5,329,734 JP 2004-82270 A JP 2003-300140 A

  The present invention makes it possible to achieve both reduction of scratches and improvement of the polishing rate in a polishing pad having holes opened in the polishing surface.

  The polishing pad according to the present invention is characterized in that, in a polishing pad having a hole opened in the polishing surface, at least an edge portion of the opening of the hole is inclined over the entire circumference.

  The holes can include both through holes and non-through holes.

  According to the present invention, since the edge portion of the opening of the hole is not sharp but is inclined, scratches can be reduced when polishing the surface of the workpiece. In reducing this scratch, unlike the groove, the edge of the hole is inclined over the entire circumference, so the surface of the object to be polished can be polished no matter how the object contacts the polishing pad. The generation of scratches can be suppressed when performing. Therefore, according to the present invention, it is possible to suppress the occurrence of scratches which are in a trade-off relationship with this while maintaining a high polishing rate due to the high holding performance of the polishing slurry, which is a feature of the holes.

  In the present invention, since the edge portion of the hole opening is inclined over the entire circumference, the surface of the object to be polished is different from that having a directionality for polishing the surface of the object to be polished like a groove. At this time, it is possible to exhibit an excellent effect that the generation of scratches can be suppressed while maintaining a high polishing rate regardless of the polishing direction.

  In particular, in the case of the present invention, since the opening edge portion is provided with an inclined surface in which the hole spreads toward the polishing surface side, the pump effect resulting from deformation of the polishing cloth when the object to be polished passes over the hole causes the inside and outside of the hole to be The replacement of the polishing slurry becomes larger. Therefore, the polishing slurry accumulated inside the hole is replaced, and a new polishing slurry is used for polishing, and the polishing debris trapped in the hole is discharged, so that the polishing rate is improved and the scratch is further improved. Will also be reduced.

  When the hole is inclined from the front surface to the entire back surface, the inclination angle between the back surface and the inner wall surface of the hole is preferably less than 90 °. When the hole is inclined halfway from the front surface to the back surface, the angle sandwiched between the line (reference line) passing through the middle portion of the hole parallel to the back surface and the inner wall surface of the hole is inclined at less than 90 °. It is good to have. When it is 90 ° or more, the polishing rate is lowered, and the occurrence of scratches is difficult to reduce.

  The polishing pad of the present invention is preferably either a nonwoven fabric type, a foamed resin type or a hard resin type.

  The holes are preferably inclined linearly or curvedly from the front surface to the back surface of the polishing pad. When the thickness is thin and the life of the polishing pad is up to almost the entire thickness, the generation of scratches during polishing of the surface of the object to be polished can be reduced until the life is reached.

  It is preferable that the hole is inclined at the predetermined inclination angle up to the thickness assumed to be the life of the polishing pad. The generation of scratches during polishing of the surface of the object to be polished can be reduced up to a thickness that is thick and reaches the life of the polishing pad.

  It is preferable that the hole has a first hole shape that extends from the inner middle portion toward the polishing pad surface and a second hole shape that extends from the inner middle portion toward the polishing pad back surface. Until the first hole shape is reached, the generation of scratches can be reduced when polishing the surface of the object to be polished, while the polishing slurry can be held in the second hole shape. Therefore, in the first hole shape alone, there is a trade-off relationship that the effect of suppressing the generation of scratches is increased by reducing the inclination angle of the edge portion of the opening on the polishing surface side, and the holding performance of the polishing slurry is lowered accordingly. However, since the holding performance of the polishing slurry can be enhanced in the second hole shape, the entire hole is set at an inclination angle that can largely suppress the generation of scratches, and at the same time, the holding performance of the polishing slurry is increased. It is possible to obtain a polishing pad excellent in performance that can be maintained sufficiently high to improve the polishing rate.

  Note that the polishing pad of the present invention is not limited to a single layer, and extends to a polishing pad having a multilayer structure, and all the polishing pads according to the present invention disposed in the upper layer are included in the present invention. it can.

  In the present invention, it is possible to reduce the scratch amount and improve the polishing rate when polishing the surface of the workpiece.

  Hereinafter, a polishing pad according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  1 and 2 show a polishing pad according to Embodiment 1. FIG. 1 is a cross-sectional view of the main part of the polishing pad, and FIG. 2 is a plan view of the main part of the polishing pad of FIG. In these drawings, reference numeral 1 denotes the polishing pad of the first embodiment. This polishing pad 1 is a nonwoven fabric type. The polishing pad 1 of the embodiment may be an independent foamed urethane type or a rigid urethane type.

  2 is a polishing surface which is the surface of the polishing pad 1, 3 is the back surface of the polishing pad 1, and 4 is a hole. The edge portion 5 of the opening on the polishing surface side of the hole 4 is inclined at an angle (inclination angle) between the back surface 3 and the inner wall surface of the hole outside the hole 4 to be α. In this case, the inner wall surface 6 of the hole 4 is inclined linearly from the polishing surface 2 to the entire back surface 3.

  According to the polishing pad 1 of the first embodiment, since the entire periphery of the opening edge portion 5 of the hole 4 is inclined (tapered), the object to be polished is polished when the object to be polished is polished using the polishing pad 1. Surface scratches can be reduced. Therefore, it is possible to reduce the generation of scratches while maintaining the high polishing rate that is a feature of the holes 4. Unlike the case where the groove is inclined, the groove 4 is inclined over the entire circumference, so that there is no direction in reducing scratches, and the surface of the polishing pad 1 and the object to be polished are removed when polishing the surface of the object to be polished. Whatever the contact relationship with the surface, it is possible to suppress or reduce the generation of scratches on the surface of the object to be polished while improving the polishing rate when polishing the surface of the object to be polished.

  The inclination angle α may be less than 90 ° in reducing scratches and improving the polishing rate in both the case where the polishing pad 1 is a nonwoven fabric type, the case of a closed foam urethane type and the case of a hard urethane type.

  3 and 4 show a polishing pad according to the second embodiment. 3A and 3B are a cross-sectional view and a main part plan view of a main part of the polishing pad, and FIGS. 4A and 4B are a main part cross-sectional view and a main part plan view of another polishing pad. In these drawings, portions corresponding to those in FIGS. 1 and 2 are denoted by the same reference numerals. In the polishing pad 1 of the second embodiment, the hole 4 shown in FIGS. 3 (a) and 3 (b) has a shallow hole depth from the opening edge portion 5 to the inner middle portion 7a, and FIGS. 4 (a) and 4 (b). The hole 4 shown in FIG. 1 has a deep hole depth from the opening edge part 5 to the inner middle part 7b. This is because the polishing pad 1 is replaced as a life after the polishing pad 1 is worn down to the thickness which is assumed to be the life of the polishing pad 1, that is, the inner middle portions 7a and 7b. The inclined portion is not always necessary, and the inner wall surface 6 inside the hole deeper than the hole inner middle parts 7a and 7b is a vertical hole. The polishing pad of the second embodiment can also reduce the generation of scratches while maintaining a high polishing rate. In the case of the second embodiment, the inclination angle α is an angle sandwiched between a line (reference line) passing through the hole inner middle portions 7a and 7b parallel to the back surface 3 and the hole inner wall surface outside the hole.

  5 and 6 show a polishing pad according to the third embodiment. FIGS. 5A and 5B are a cross-sectional view and a main part plan view of the main part of the polishing pad, and FIGS. 6A and 6B are a cross-sectional view and a main part plan view of the main part of another polishing pad. In these drawings, portions corresponding to those in FIGS. 1 and 2 are denoted by the same reference numerals. In the polishing pad 1 according to the third embodiment, the hole 4 shown in FIGS. 5A and 5B has a curved hole shape from the opening edge portion 5 to the inner middle portion 7a, and FIGS. The hole 4 indicated by () is curved from the opening edge part 5 to a position deeper from the inner intermediate part 7b than the hole 4 shown in FIGS. 5 (a) and 5 (b). This is because the polishing pad 1 is replaced as a life after the polishing pad 1 is worn down to the thickness which is assumed to be the life of the polishing pad 1, that is, the inner middle portions 7a and 7b. The inclined portion is not always necessary, and the inner wall surface 6 inside the hole deeper than the hole inner middle parts 7a and 7b is a vertical hole. In addition to this, the hole shape from the opening edge portion 5 of the hole 4 to the inner middle portion 7a is curved so that the generation of scratches can be further suppressed during polishing of the object to be polished. The polishing pad of Embodiment 3 can also reduce the occurrence of scratches while maintaining a high polishing rate. In the case of the third embodiment, the inclination angle α is an angle between a line (reference line) passing through the hole inner middle portions 7a and 7b in parallel with the back surface 3 and the hole inner wall surface.

  7 and 8 show a polishing pad according to the fourth embodiment. 7 is a cross-sectional view of the main part of the polishing pad, and FIG. 8 is a plan view of the main part of the polishing pad of FIG. In these drawings, portions corresponding to those in FIGS. 1 and 2 are denoted by the same reference numerals. In the polishing pad 1 of Embodiment 4, the shape of the hole 4 is changed to a hole shape 4a extending from the inner middle portion 7 in the direction of the polishing surface 2, and from the inner middle portion 7 to a hole shape 4b extending in the direction of the back surface 3. It has become. In the hole shape 4a, the edge portion 5 is inclined by the inclination angle α to suppress the occurrence of scratches when polishing the object to be polished. In the hole shape 4b, polishing slurry can be stored to improve the polishing rate. In particular, the polishing pad of the fourth embodiment can improve the polishing rate and reduce scratches. The inclination angle α of the first hole shape is an angle between a line (reference line) passing through the hole inner middle part 7 in parallel with the back surface 3 and the hole inner wall surface.

  After opening a hole of any size with a punch for a non-woven type polishing pad (Nitta Haas Co., Ltd. SUBA) and an independent foam type polishing pad (Nitta Haas Co., Ltd. MH), A three-dimensional processing machine (NC router) was used to chamfer with a blade for a set angle, and the wall surface of the hole opening was inclined to obtain a polishing pad having holes with inclined angles as shown in FIG. FIG. 9 shows a non-woven fabric type polishing pad and a closed foam urethane type polishing pad in common. Both types of polishing pads change the inclination angle of the holes into 8 types (20 °, 30 °, 40 °, 50 °, 60 °, 70 °, 80 °, 90 °), and the holes at each inclination angle. Each of the polishing pads having a surface is affixed to a lower surface plate of a single-side polishing machine (Poly-500 manufactured by G & P Co.) via a double-sided adhesive tape, and an object to be polished held on the surface of the carrier head facing the surface. Polishing was performed while supplying a polishing slurry to the interface while pressing the wafer, and the scratch amount of the wafer was measured using a wafer surface inspection device (LS6600, manufactured by Hitachi High-Tech Electronics Engineering Co., Ltd.).

 The above measurement results are shown in Table 1.

表１に示す測定結果から明らかであるように、孔の開口エッジ部の全周にわたり傾斜をつけた研磨パッドにより、被研磨物に対する研磨レートの向上とスクラッチの抑制とができた。

As is apparent from the measurement results shown in Table 1, the polishing pad with an inclination over the entire circumference of the opening edge of the hole was able to improve the polishing rate for the object to be polished and suppress scratches.

  Specifically, regarding the scratch, when 90 ° is 1 (the scratch amount per unit surface area (for example, the number of scratches) is 1), in the case of the nonwoven fabric type, the smaller the inclination angle α, the lower the scratch is 80 ° or less. Reduced from 0.98 to 0.73 at 20 ° or more, and in the case of closed-cell foamed urethane type, the smaller the inclination angle α, the smaller the scratch, and 80 ° or less, from 0.93 to 0.63 at 20 ° or more. Reduced.

  As for the polishing rate, assuming that 90 ° is 1, in the case of the nonwoven fabric type, the smaller the inclination angle α, the higher the polishing rate and the improvement from 1.00 to 1.08 at 80 ° or less and 20 ° or more. In the case of the urethane foam type as well, the polishing rate improved as the inclination angle α decreased, and improved from 1.02 to 1.09 at 80 ° or less and 20 ° or more.

  Note that the measurement data is obtained by changing eight types of inclination angles α, and the inclination data α is not limited to the above eight types as long as the inclination angle α is less than 90 °.

It is principal part sectional drawing of the polishing pad which concerns on Embodiment 1 of this invention. It is a principal part top view of the polishing pad of FIG. (A) It is principal part sectional drawing of the polishing pad which concerns on Embodiment 2 of this invention, (b) It is a top view of Fig.3 (a). (A) It is principal part sectional drawing of the polishing pad which concerns on the deformation | transformation of Embodiment 2 of this invention, (b) It is a top view of Fig.4 (a). (A) It is principal part sectional drawing of the polishing pad which concerns on Embodiment 3 of this invention, (b) It is a top view of Fig.5 (a). (A) It is principal part sectional drawing of the polishing pad which concerns on the deformation | transformation of Embodiment 3 of this invention, (b) It is a top view of Fig.6 (a). It is principal part sectional drawing of the polishing pad which concerns on Embodiment 4 of this invention. It is a principal part top view of the polishing pad of FIG. It is principal part sectional drawing of the polishing pad used for the Example.

Explanation of symbols

1 Polishing pad 2 Polishing surface (surface)
3 Back 4 Hole 5 Open edge

Claims (6)

  A polishing pad having a hole opened in a polishing surface, wherein at least an edge portion of the opening of the hole is inclined over the entire circumference.   The polishing pad according to claim 1, wherein an angle between the back surface or a line parallel to the back surface (reference line) and the inner wall surface of the hole is less than 90 °.   The polishing pad according to claim 1 or 2, wherein the polishing pad is of a nonwoven fabric type, a foamed resin type or a hard resin type.   The polishing pad according to any one of claims 1 to 3, wherein the holes are inclined and opened in a linear or curved shape.   The polishing pad according to any one of claims 1 to 3, wherein the hole is opened in a linear or curved shape up to a thickness that is assumed to be a life of the polishing pad. .   4. The hole according to claim 1, wherein the hole has a hole shape extending in the direction of the surface of the polishing pad from the middle part of the inside, and a hole shape extending in the direction of the back surface of the polishing pad from the middle part of the inside. The polishing pad according to claim 1.

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