JP2013151058A - Polishing pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing pad that allows a user to easily recognize a wear state of a polishing face.SOLUTION: A polishing pad 1 is provided on a polishing surface 1a thereof with: grooves 2 serving as slurry flow paths; and informing portions formed of a plurality of bottomed recesses 10a, 10b, and 10c which are visually recognizable and have different depths. The plurality of informing portions are provided as a group at respective different parts on the polishing face. A user can recognize wear of the polishing pad when the polishing face 1a has reached a predetermined wearing amount and the informing portions have disappeared to be visually unrecognizable.

Description

  The present invention relates to a polishing pad for polishing an object to be polished, and more particularly to a polishing pad suitable for polishing a silicon wafer by chemical mechanical polishing (CMP) in a semiconductor manufacturing process.

  This type of polishing pad is generally disc-shaped, and is used by being bonded to the upper surface of a lower surface plate (turn table) in a polishing apparatus, for example. In such a polishing step, the wafer held on the lower surface of the upper surface plate is pressed against the upper surface, which is the polishing surface of the polishing pad, and the lower surface plate is rotated and the upper surface plate is also rotated while supplying the slurry from the slurry supply device. Polish the wafer. In addition, in order to perform efficient polishing, grooves serving as a slurry flow path may be formed in a lattice shape or concentric circles on the polishing surface, or many through holes may be formed (Patent Document 1).

JP 2002-160153 A

  The polishing surface of such a polishing pad is worn by dressing for eliminating clogging of the polishing surface in addition to wear caused by polishing the workpiece itself. When the polishing surface is worn, for example, when grooves are formed as described above, the depth of the grooves becomes shallow, and the polishing ability is different from the initial state. Further, since the entire polished surface is often worn unevenly rather than uniformly, the flatness of the polished surface is also deteriorated compared to the initial state. In any case, if the polishing pad continues to be used for a long period of time, it will result in a decrease in the yield of the wafer due to abrasion of the polishing surface, but it is not easy to grasp the degree of wear, In the actual situation, the polishing pad is not used up to the end, but rather is replaced with a new one at a timing earlier than the lifetime, thereby preventing a decrease in the yield of the wafer.

  Therefore, the present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a polishing pad that allows a user to easily grasp the wear state of the polishing surface.

  The present invention has been made to solve the above problems, and a polishing pad according to the present invention is a groove formed on a polishing surface, which is a groove serving as a slurry flow path, and is visually recognized on the polishing surface. It is a notification unit comprising a bottomed recess provided in a possible manner, and includes a plurality of notification units forming a group at each of different locations on the polishing surface, and each of the plurality of notification units forming a group has a depth. It is characterized by being formed differently.

  As one aspect of the present invention, it is preferable that the notification section is provided at a position different from the groove arrangement.

  As another aspect of the present invention, the bottom surface of the notification unit may be colored.

  As another aspect of the present invention, the bottom surfaces of a plurality of notification units forming a group may be colored in different colors.

  Moreover, as another aspect of the present invention, each of the plurality of notification units forming a group may be formed with a different size or shape.

  According to the present invention, the user can easily grasp the replacement time of the polishing pad by the notification unit, and it is not necessary to replace the pad by relying on experience as in the past, and it is always based on a constant and objective standard. Pad replacement can be performed.

The top view which shows the polishing pad in one Embodiment of this invention. (A) is the A section enlarged view of FIG. 1, (b) is the PP sectional view taken on the line (b). The top view which shows the polishing pad in other embodiment of this invention. The top view which shows the polishing pad in other embodiment of this invention. The top view which shows the polishing pad in other embodiment of this invention. The top view which shows the polishing pad in other embodiment of this invention. The top view which shows the polishing pad in other embodiment of this invention. The top view which shows the polishing pad in other embodiment of this invention. The top view which shows the polishing pad in other embodiment of this invention. The principal part enlarged view of the polishing pad in other embodiment of this invention. The principal part expanded sectional view of the polishing pad in other embodiments of the present invention.

  Hereinafter, an embodiment of a polishing pad according to the present invention will be described with reference to FIGS.

  The polishing pad includes a single-layer structure that entirely constitutes a polishing layer, and a multi-layer structure in which a cushion layer is laminated below the polishing layer via an adhesive layer. FIG. 1 shows a single-layer structure. A polishing pad 1 is shown.

  The polishing pad 1 has, for example, polyurethane as a main component and has a structure having bubbles inside by foaming. Specifically, it is a urethane polymer resin pad obtained by foaming and curing a polyurethane resin. Examples of the urethane polymer resin pad include polyether urethane resins, polyester urethane resins, polyester ether urethane resins, and polycarbonate urethanes. Resin etc. can be used. Examples of the foaming method include a method of mixing micro hollow bodies, a method of using a foaming agent, a method of introducing bubbles, a method of reprecipitation of dissolved gas, etc., and a closed cell type in which each cell is independent from each other is particularly preferable. . The same applies to the polishing material in the case of a multilayer structure.

  Since the lower surface 1b of the polishing pad 1 is generally fixed to a lower surface plate, the polishing pad 1 is formed in a thin disk shape corresponding to the size of the lower surface plate, and the upper surface thereof is a polishing surface 1a. Become. And the groove | channel 2 which becomes a flow path while holding a slurry is formed in the grinding | polishing surface 1a. The groove 2 has, for example, a depth of about 40% of the polishing layer. In the case of a single layer structure, the groove 2 has a depth of about 40% of the entire thickness of the polishing pad 1. As shown in FIG. 1, a large number of the grooves 2 are concentrically formed in the entire region except the central portion 1 c of the polishing pad 1 with a center C of the polishing pad 1 being spaced from each other.

  A polishing pad 1 is provided on the polishing pad 1 for informing when the polishing surface 1a is worn by a predetermined amount. Specifically, a bottomed recess 10 is formed on the polishing surface 1a as a notification unit. The bottomed recess 10 is a disappearing portion that disappears when the polishing surface 1a is worn by a predetermined amount, and is present until the polishing surface 1a is worn by a predetermined amount and disappears when the polishing surface 1a is worn by a predetermined amount. The person can visually recognize the presence or absence.

  The bottomed recess 10 is a bottomed hole that does not penetrate, specifically a round hole, and has a diameter of 1 to 3 mm and a depth of 0.3 to 0.5 mm, for example. However, the shape is not limited to a round hole, and may be a rectangular shape or a groove shape. A plurality of bottomed recesses 10 having different depths, specifically, three bottomed recesses 10a, 10b, and 10c are formed as one group. Although the three bottomed recesses 10a, 10b, and 10c constituting the group are all shallower than the groove 2, for example, the depths thereof are large, medium, and small. As shown in FIG. 2, the group of three bottomed recesses 10 a, 10 b, and 10 c are formed between the adjacent grooves 2, and are arranged in a line along the grooves 2. In FIG. 1 and FIG. 2, the bottomed concave portion 10a having a large depth from the upper side of the paper, the bottomed concave portion 10b in the depth, and the bottomed concave portion 10c having a small depth are arranged in this order.

  Further, the group of three bottomed recesses 10a, 10b, and 10c are formed not at one place on the polishing surface 1a but at a plurality of places, specifically, a plurality of places having different distances from the center C. More specifically, an inner peripheral portion having a small distance from the center C, a midway portion (A portion) having a distance larger than that of the polishing pad 1 and approximately half the radius of the polishing pad 1, and a distance larger than that and close to the periphery. The outer peripheral portion is formed at a total of three locations, and in particular, these three locations are linearly arranged in the radial direction without being displaced from each other in the circumferential direction. Note that the group of bottomed recesses 10 in the outermost outer peripheral portion is formed further outward than the outermost groove 2. In this way, the three bottomed recesses 10a, 10b, and 10c having large, medium, and small depths are formed as a group at a total of three locations having different distances from the center C, so that the distance from the center C is the same. Three bottomed recesses 10 having different depths are formed, and three bottomed recesses 10 having the same depth, that is, three bottomed recesses 10c having three different distances from the center C are provided. The bottomed recess 10b in the depth is also formed at each of the three locations, and the bottomed recess 10a having a large depth is also formed at each of the three locations. The bottomed recess 10 can be formed by, for example, a drill or an end mill.

  The polishing pad 1 in the present embodiment has the following advantages by adopting the above configuration. That is, since the bottomed recess 10 is formed on the polishing surface 1a, the polishing surface 1a is worn by dressing or the like, and when the amount of wear reaches a predetermined amount, the bottomed recess 10 disappears. Therefore, the user can know that the abrasion amount of the polishing surface 1a has reached a predetermined amount when the bottomed recess 10 disappears. Specifically, the bottomed concave portion 10c having a small depth disappears at the earliest time, and then the bottomed concave portion 10b in the depth and the bottomed concave portion 10a having a large depth disappear in that order. For example, the depth of the bottomed recess 10a having a large depth is set such that the time when the padded replacement occurs when the deep bottomed recess 10a disappears, and the bottomed recess in the depth is further set. 10b is set to a depth of 2/3 of the bottomed concave portion 10 having a large depth, and a bottomed concave portion 10c having a small depth is set to a depth of one third of the bottomed concave portion 10 having a large depth. It can be seen that the bottomed concave portion 10c having a small depth has disappeared, and that about 1/3 of the pad life has been reached. When the bottomed concave portion 10b in the depth disappears, it can be seen that the remaining pad life is about 1/3, and when the deep bottomed concave portion 10a disappears, the pad life comes and the pad replacement time is reached. It can be seen that it is. Thus, by forming the bottomed recesses 10 having different depths, the degree of wear of the polishing surface 1a can be grasped in detail.

  In addition, since the three bottomed recesses 10a, 10b, and 10c having large, medium, and small depths are provided at three different distances from the center C, it is possible to grasp the difference in the degree of wear depending on the location. For example, in the case where only a specific part wears unevenly, for example, the outer peripheral part is particularly worn, the bottomed recesses 10 having the same depth are arranged at different parts as shown in FIG. Thus, it is possible to easily grasp the degree of wear caused by the place, such as which place has the highest degree of wear.

  In the present embodiment, the case where the bottomed concave portion 10 is formed so as to be separated from the groove 2 between the adjacent grooves 2 has been described. However, as shown in FIG. You may form the bottomed recessed part 10 so that it may do. Further, only one of the adjacent grooves 2 may be communicated. In any case, when the bottomed recess 10 is formed so as to communicate with the groove 2, unnecessary materials such as polishing debris accumulated in the bottomed recess 10 can be discharged through the groove 2. In particular, when communicating with both of the grooves 2, the adjacent grooves 2 communicate with each other by the bottomed recess 10 therebetween, and therefore, movement of unnecessary materials such as polishing debris from the groove 2 to the groove 2. Is also preferable.

  Further, in the above embodiment, the case where the group consisting of the bottomed recesses 10 having three depths is arranged at a total of three places, but the number and arrangement places of the groups can be appropriately changed in design, For example, as shown in FIG. 3, a total of five locations may be formed at regular intervals from the inner circumference side to the outer circumference side. The total number of the bottomed recesses 10 varies depending on the shape, size, depth, etc. of the bottomed recesses 10. For example, if the number is about several tens (about 20), the polished state of the object to be polished is Has little effect.

  In addition, the group of bottomed recesses 10 may not be arranged linearly from the inner circumference side toward the outer circumference side as shown in FIGS. 1 and 3, but may be arranged so as to be displaced from each other in the circumferential direction. For example, a group of three bottomed recesses 10a, 10b, and 10c having a depth may be arranged while being gradually shifted in the circumferential direction from the inner peripheral side to the outer peripheral side. For example, as shown in FIG. You may arrange.

  Furthermore, there are various configurations other than a configuration in which a plurality of bottomed recesses 10 having different depths are arranged as one group, and a plurality of bottomed recesses 10 having different depths can be randomly arranged. A plurality of bottomed recesses 10 having one kind of depth can be formed. When only one type of depth is used, it is preferable to be able to grasp the pad replacement time. Therefore, the depth is set to a depth that disappears when the wear amount of the polishing surface 1a reaches a predetermined amount that becomes the pad life. It is preferable. As for the arrangement, there are a wide variety of arrangement patterns as in the case of arrangement in groups. For example, as shown in FIG. 5, every predetermined angle in the circumferential direction from the inner peripheral side to the outer peripheral side (in FIG. 5, 90 degrees each) ) It can be arranged in a spiral while being displaced. Further, as shown in FIG. 6, the bottomed recesses 10 may be linearly arranged from the inner peripheral side to the outer peripheral side (row α), or may be arranged in a curved shape from the inner peripheral side to the outer peripheral side (row). β), the column shape may be anything. And it is sufficient to provide one row of bottomed recesses 10 arranged from the inner periphery side to the outer periphery side, but a plurality of rows can be provided as shown in FIG. Thus, there are various arrangement modes of the bottomed recess 10.

  In addition, although the case where the grooves 2 serving as the slurry flow paths are provided concentrically has been described, it is of course possible to provide the grooves 2 in a lattice shape, and even in that case, there are three large, medium, and small depths similar to those described above. The group of bottom recesses 10a, 10b, and 10c can be arranged at three locations, for example, an inner peripheral portion, a midway portion, and an outer peripheral portion as shown in FIG. When the grooves 2 are formed in a lattice shape, the bottomed recesses 10 having three large, medium, and small depths can be linearly arranged along the linear grooves 2 as shown in FIG.

  Further, the bottomed recesses 10a, 10b, and 10c having the depths of large, medium, and small may be arranged at intervals in the circumferential direction without being arranged at one place, for example, from the center C as shown in FIG. The three bottomed recesses 10a, 10b, and 10c having large, medium, and small depths are respectively disposed at three locations of the inner peripheral portion, the middle portion, and the outer peripheral portion having different distances. 10b and 10c are arranged at a large distance from each other in the circumferential direction, and as a result, three bottomed concave portions 10a, bottomed concave portions 10b in three depths, and three bottomed concave portions 10c may be arranged in a straight line from the inner circumference side toward the outer circumference side.

  Furthermore, as shown in FIG. 9, three bottomed recesses 10a, 10b, and 10c having large, medium, and small depths are concentrically arranged at intervals of 90 degrees from each other, and three bottomed recesses 10a that are large, medium, and small in depth. , 10b, and 10c may be shifted in a spiral manner by 225 degrees from the inner peripheral side to the outer peripheral side.

  4, 5, 8, and 9 are not actually formed on the polishing surface 1 a, but are virtual circles and straight lines.

  Of course, in addition to the case where the bottomed recesses 10a, 10b, and 10c having three large, medium, and small depths are provided, it is of course possible to have two types of depths of large and small or four or more types.

  The disappearance of the bottomed recess 10 may be more clearly visible by coloring the bottom surface of the bottomed recess 10. When forming the bottomed recessed part 10 from which depth differs, the difference in the depth may be shown according to color. In addition to showing the difference in depth by color, for example, the difference in bottom may be determined by the size and shape of the bottomed recess 10.

  Further, as the disappearing portion, in addition to the bottomed recessed portion 10 as described above, a part of the groove 2 can be formed shallowly as shown in FIG. 11, and the shallow groove portion 20 can be configured as the disappearing portion. In FIG. 11, reference numeral 2 a indicates the bottom surface of the groove 2. As described above, even when the shallow groove portion 20 is configured as the disappearance portion, the depth of the shallow groove portion 20 can be provided in a plurality of types, for example, three types of depth, large, medium, and small, as in the case of the bottomed recessed portion 10. Since it disappears in order from the shallowest, it is possible to grasp the current degree of wear more accurately. In FIG. 11, shallow grooves 20 a, 20 b, and 20 c having large, medium, and small depths are formed along the longitudinal direction of the groove 2 (in the direction of arrow B) in that order. Since the shallow groove portion 20 can be formed together with the processing of the groove 2, the disappearance portion can be easily processed. FIG. 11 shows a polishing pad 1 having a multilayer structure, in which a cushion layer 102 is laminated below the polishing layer 100 via an adhesive layer 101, and the cushion layer 102 is attached to a lower surface plate. An adhesive layer 103 is formed. Further, a groove (slit) may be formed separately from the groove 2, and shallow grooves 20a, 20b, and 20c having different depths as shown in FIG. 11 may be formed in the groove. As described above, the disappearing portion has various configurations such as the bottomed concave portion 10 and the shallow groove portion 20, but in any case, it may be any configuration that disappears when the polishing surface 1 a is worn by a predetermined amount.

  In addition, although the case where the vanishing part is provided as the notification part has been described, a notification part configured to be exposed on the polishing surface 1a when the polishing surface 1a is worn by a predetermined amount inside the polishing surface 1a is employed. Is also possible.

  In addition, it is preferable to provide a visually recognizable notification portion on the polishing surface 1a, but it is also possible to provide it on the peripheral surface (reference numeral 1d in FIG. 1) other than the polishing surface 1a.

  DESCRIPTION OF SYMBOLS 1 ... Polishing pad, 1a ... Polishing surface (upper surface), 2 ... Groove, 10, 10a, 10b, 10c ... Bottomed recessed part, 20, 20a, 20b, 20c ... Shallow groove part

Claims (5)

  A groove formed on the polishing surface, which is a notifying portion including a groove serving as a flow path for the slurry and a bottomed recess provided on the polishing surface so as to be visible, each of different locations on the polishing surface And a plurality of notification parts forming a group, and each of the plurality of notification parts forming a group is formed with a different depth.   The polishing pad according to claim 1, wherein the notification portion is provided at a position different from the arrangement of the grooves.   The polishing pad according to claim 1, wherein a bottom surface of the notification unit is colored.   3. The polishing pad according to claim 1, wherein the bottom surfaces of the plurality of notification units forming a group are colored in different colors.   The polishing pad according to any one of claims 1 to 3, wherein each of the plurality of notification units forming a group is formed with a different size or shape.

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