JP2014195840A - Abrasive pad - Google Patents

Abstract

Disclosed is a polishing pad capable of suppressing the consumption of polishing slurry, maintaining the flatness of the polishing surface, and improving the dispersibility of the polishing slurry. A polishing pad has a circular polishing surface, and includes a plurality of annular grooves extending so as to draw an elliptical shape, and the plurality of annular grooves extending so as to draw an elliptical shape are short in length. It arrange | positions so that the axis | shaft S may extend in the radial direction of the grinding | polishing surface 9, and the end of the short axis S may overlap with the periphery of the grinding | polishing surface 9 which makes | forms a circle. [Selection] Figure 2

Description

  The present invention relates to a polishing pad, and more particularly to a polishing pad used when an object to be polished is polished by a chemical mechanical polishing method.

  Conventionally, a chemical mechanical polishing method (CMP method) has been used as a method for polishing and flattening the surface of an object to be polished such as a semiconductor wafer, a glass substrate for a liquid crystal display, a glass substrate for a photomask, or a glass substrate for a magnetic disk. Is used. When polishing an object to be polished using the CMP method, the polishing pad is pressed against the object to be polished, and the polishing pad and the object to be polished are rotated while supplying the polishing slurry between them. The polishing slurry flows from the center side toward the outside by centrifugal force accompanying the rotation of the polishing pad, and is finally discharged to the outside of the polishing pad. In recent years, the polishing slurry is evenly and sufficiently spread over the surface of the object to be polished, and the object to be polished is flattened uniformly and with high accuracy, the consumption of expensive polishing slurry is suppressed, and the cause of scratching In order to achieve efficient discharge of polishing scraps, a technique for forming grooves of various shapes including concentric, spiral, and instructor shapes on the polishing surface of the polishing pad is often used. The technique described in Document 1 is known.

Japanese Patent No. 5124212

  The polishing pad described in Patent Document 1 has a groove in which two spiral shapes swirling in opposite directions are overlapped.

  However, since the polishing pad described in Patent Document 1 has two spiral grooves swirling in opposite directions, the ratio of the grooves to the polishing surface, that is, the groove density is increased. At the time of polishing, basically, it is necessary to fill all the grooves with the polishing slurry. However, if the groove density is high as in the polishing pad described in Patent Document 1, the polishing slurry is applied to the entire polishing surface. In order to spread and fill the groove with the polishing slurry, a large amount of polishing slurry is required. Therefore, when the polishing pad described in Patent Document 1 is used, there is a problem that consumption of expensive polishing slurry increases. In particular, during polishing, the grooves in the regions that do not contact the object to be polished and do not contribute to polishing are also filled with the polishing slurry. However, the grooves in the regions that do not contribute to polishing are always filled with the polishing slurry. Otherwise, a large amount of the polishing slurry is discharged from the groove without being used.

  Therefore, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a polishing pad that can suppress the consumption of polishing slurry.

  In order to solve the above-described problems, the present invention is a polishing pad having a circular polishing surface, comprising a plurality of elliptical grooves, the minor axis of which is the radial direction of the polishing surface And one end of the short axis is arranged so as to overlap the circumference of the circular polishing surface.

  According to the present invention configured as described above, it is possible to provide a polishing pad having a plurality of annular grooves which are drawn in an elliptical shape and arranged so as to be in contact with the circumference of a circular polishing surface. Such an annular groove of the polishing pad can suitably discharge and hold the polishing liquid. In other words, the annular groove having an elliptical shape is constituted by two semi-annular grooves extending in an arc shape. When the polishing pad having such two semi-annular grooves is rotated, one of the semi-annular grooves is convex toward the downstream side in the rotation direction, and between the center of the polishing pad and the side wall of the polishing pad. The polishing liquid can be dispersed, and the other semi-annular groove can be convex toward the upstream side in the rotation direction to return the polishing liquid to the center direction of the polishing pad. Therefore, according to the present invention thus configured, the polishing slurry can be suitably held without increasing the number of grooves and unnecessarily increasing the groove density, thereby reducing the consumption of expensive polishing slurry. Can be suppressed.

  In this case, each of the plurality of annular grooves has a connecting portion connected to another annular groove in a curved portion extending from one end to the other end of the short axis, and the number of connecting portions is four. It is preferable that there are no more.

  Further, in the polishing pad described in Patent Document 1, since two spiral grooves that rotate in opposite directions are formed, the land polishing surface portion between the grooves has a sharp shape. Since the sharp land polishing surface portion is easily deformed with respect to the sliding direction of the width polishing pad, the polishing pad described in Patent Document 1 has a problem that the flatness of the polishing surface cannot be maintained. .

  Furthermore, in the polishing pad described in Patent Document 1, since the number of intersections between the grooves is very large, the fluidity of the polishing slurry is reduced at the intersections between the grooves, and as a result, the polishing slurry is sufficiently dispersed. This problem is remarkable in the central region of the polishing pad where the centrifugal force is weak.

  On the other hand, according to the present invention, the number of sharply polished surfaces can be reduced by limiting the number of coupling portions to four or less. Thereby, the flatness of the polished surface can be maintained. Moreover, the location where the fluidity | liquidity of polishing slurry falls can be reduced by making the number of connection parts into four or less, and, thereby, it can suppress that the fluidity | liquidity of polishing slurry falls.

  As described above, according to the present invention, the consumption of the polishing slurry can be suppressed, the flatness of the polishing surface can be maintained, and the dispersibility of the polishing slurry can be enhanced.

1 is a cross-sectional view showing a single-side polishing apparatus to which a polishing pad according to an embodiment of the present invention is applied. It is the top view which looked at the polishing pad by the embodiment of the present invention from the polish side. FIG. 3 is an enlarged view of region III in FIG. 2. It is the top view which looked at the polishing pad by the modification of embodiment of this invention from the polishing surface side. It is the top view which looked at the polishing pad by the modification of embodiment of this invention from the polishing surface side. It is the top view which looked at the polishing pad by the modification of embodiment of this invention from the polishing surface side. It is the top view which looked at the polishing pad by the modification of embodiment of this invention from the polishing surface side. It is the top view which looked at the polishing pad by the modification of embodiment of this invention from the polishing surface side.

  Hereinafter, a polishing pad according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a single-side polishing apparatus to which a polishing pad according to an embodiment of the present invention is applied.

  First, as shown in FIG. 1, a single-side polishing apparatus 1 flattens a surface of an object to be polished 3 by a CMP method. The single-side polishing apparatus 1 includes a polishing surface plate 5 that rotates about a rotation axis, a polishing pad 7 that is fixed to the upper surface of the polishing surface plate 5, a dresser 11 that conditions the polishing surface 9 of the polishing pad 7, A holding surface plate 13 for holding the polished article 3 and a polishing slurry supply device 15 for supplying polishing slurry to the polishing surface 9 are provided.

  Such a single-side polishing apparatus 1 rotates the polishing surface plate 5 and the holding surface plate 13 while rotating the polishing surface plate 5 and the holding surface plate 13 while supplying the polishing slurry from the polishing slurry supply device 15 to the vicinity of the center of the polishing surface 9 of the polishing pad 7. The surface of the object to be polished 3 held at 13 is flattened.

  The polishing surface plate 5 is made of metal and has a disk shape. One surface of the polishing surface plate 5 constitutes an affixing surface to which the polishing pad 7 is affixed, and this affixing surface is substantially flat.

  The holding surface plate 13 is made of metal and has a disk shape whose diameter is smaller than that of the polishing surface plate 5. One surface of the holding surface plate 13 constitutes an affixing surface to which the holding pad 17 is affixed, and this affixing surface is substantially flat.

  The polishing pad 7 is, for example, a hard polyurethane pad manufactured by a dry method that is formed by curing with a reaction between a prepolymer containing an isocyanate group-containing compound and a curing agent, and has the same diameter as the polishing surface plate 5. It is made into a disk shape. One circular surface of the disc-shaped polishing pad 7 constitutes the polishing surface 9. The polishing pad 7 is detachably attached to the polishing surface plate 5. In addition, the “disk-shaped” and “circular” polishing pads in the present specification and claims mean to include a donut-shaped polishing pad in which the vicinity of the center portion is cut out in addition to the circular shape. Yes.

  The holding pad 17 is, for example, a soft plastic pad, and has a disk shape having the same diameter as that of the holding surface plate 7. The holding pad 17 is detachably attached to the holding surface plate 13.

  FIG. 2 is a plan view of the polishing pad as viewed from the polishing surface side. A plurality of annular grooves 19 are formed on the polishing surface 9 of the polishing pad 7. The annular groove 19 is formed to hold and disperse the polishing slurry when the polishing pad is rotated in the direction of arrow A. The annular groove 19 has an elliptical shape, and is arranged such that its short axis S overlaps the radius of the polishing surface 9 forming a circle. One end of the short axis S of the annular groove 19 overlaps the outer periphery of the polishing surface 9, and the other end is positioned near the center of the polishing surface 9. As the cross-sectional shape of the annular groove 19, any known cross-sectional shape such as a V shape, a rectangle, or a semicircular shape can be adopted.

  In the present specification, the term “elliptical shape” means not only a standard ellipse represented on a two-dimensional orthogonal coordinate system, but also a longest longest diameter when connecting two points on the circumference, It includes any curve in which the minor axis that becomes the shortest when connecting two points is orthogonal.

  The elliptical shape is preferably a standard ellipse in which the sum of the distances from two fixed points is constant. In this case, the ellipticity (minor axis / major axis) is 0.3 to 0.85. The range is preferable, and the range of 0.5 to 0.7 is more preferable.

  The plurality of annular grooves 19 have the same shape and are arranged so as to surround the center of the polishing surface 9. In the example shown in FIG. 2, polishing is performed by arranging three annular grooves 19 at equal angular intervals. The pad 7 is shown. The plurality of annular grooves 19 are connected to each other, and are configured to allow polishing slurry to flow from one annular groove to another annular groove. As an aspect for connecting the annular grooves 19, as shown in FIG. 2, there is an aspect in which the annular grooves 19 are arranged so that the annular grooves 19 are in contact with each other.

  The number of the annular grooves 19 can be appropriately selected within a range of 3 to 8. This is not preferable if the number of the annular grooves 19 is two, because a portion that does not intersect with the annular grooves 19 is formed when a radial straight line is drawn from the center of the polishing surface 9. Further, if the number of the annular grooves 19 is more than 8, the number of portions where the annular grooves 19 intersect with each other increases, which is not preferable because the fluidity of the polishing slurry decreases.

  FIG. 3 is an enlarged view of region III in FIG. As shown in FIG. 3, the annular groove 19 is disposed so as to contact the circumference of the polishing surface 9 forming a circle. Here, the annular groove 19 is in contact with the circumference of the polishing surface 9 forming a circle. The annular groove 19 is in contact with the circumference of the polishing surface 9 between both ends of the groove width of the annular groove 19. 7 is open to the outside in the radial direction of the polishing pad 7.

  In addition, as shown in FIG. 2, by forming the annular groove 19 into an elliptical shape, the annular groove 19 can be regarded as substantially constituted by two semi-annular grooves 19a and 19b. Each semi-annular groove 19a, 19b is configured by a quadratic curve extending from one end of the short axis S to the other end. One end of each semi-annular groove 19a, 19b is open toward the peripheral wall of the polishing pad 7 around the circular polishing surface 9 and the other end extends to the vicinity of the center of the polishing surface 9. The semi-annular groove 19a is located on the downstream side in the rotation direction when the polishing pad 7 is rotated in the direction of arrow A, and becomes convex toward the downstream side in the rotation direction to disperse the polishing slurry. On the other hand, the semi-annular groove 19b is located on the upstream side in the rotational direction when the polishing pad 7 is rotated in the direction of arrow A, becomes convex toward the upstream side in the rotational direction, and returns the polishing slurry to the central direction.

  As shown in FIG. 2, when the workpiece 3 is polished while the polishing pad 7 is rotated in the direction of arrow A, the polishing slurry dropped from the polishing slurry supply device 15 to the vicinity of the center of the polishing surface 9 is polished by the centrifugal force. 9 diffuses in the radial direction and flows between the workpiece 3 and the polishing surface 9. The polishing slurry that has flowed into the annular groove 19 flows into the semi-annular groove 19a that protrudes on the downstream side in the rotational direction, and flows and discharges along the semi-annular groove 19a in the outer diameter direction along the semi-annular groove 19a. At this time, the polishing slurry that has entered the semi-annular groove 19b from the polishing surface near the semi-annular groove 19b on the upstream side in the rotation direction returns to the center direction of the polishing surface 9 along the semi-annular groove 19b by centrifugal force. Since the annular groove 19 is arranged so as to contact the circumference of the polishing surface 9, the angle between the outer periphery of the polishing pad and the semi-annular groove 19 b becomes small, and the slurry that flows into the semi-annular groove 19 b from the vicinity of the outer periphery of the polishing pad 7. Becomes easy to move toward the center.

  Thus, the elliptical annular groove 19 is formed on the polishing surface 9, the polishing slurry is discharged by the semi-annular groove 19 a, and the polishing slurry can be returned to the center direction of the polishing surface 9 by the semi-annular groove 19 b. Thereby, the retention property of the polishing slurry by the polishing pad 7 can be improved, and consumption of the polishing slurry can be suppressed.

  Further, by arranging the annular grooves 19 extending in an elliptical shape on the polishing surface 9, a sufficient amount of polishing slurry can be supplied onto the polishing surface 9 with a small number of annular grooves 19. Further, since only three annular grooves 19 are formed on the polishing surface 9, the ratio of the annular grooves 19 when the polishing surface 9 is viewed in plan is relatively small. There is no need to supply a large amount of polishing slurry to fill.

  As described above, when the three annular grooves 19 are arranged on the polishing surface 9 so as to be in contact with each other, the semi-annular groove 19a or the semi-annular groove 19b of one annular groove 19 has another annular groove at one place. The groove is connected to the semi-annular groove 19b or the semi-annular groove 19a. Thereby, the number of connecting portions between the annular grooves 19 can be reduced. And by reducing the number of the connection part of the groove | channel where the fluidity | liquidity of polishing slurry tends to fall, it can suppress that the fluidity | liquidity of polishing slurry falls.

  It is preferable that the plurality of annular grooves 19 have the same shape because variations in the slurry distribution on the polishing pad 7 are reduced and the object to be polished can be processed at a stable polishing rate.

  Next, a modification of the embodiment of the present invention will be described.

  4 to 8 are plan views of the polishing pad according to the modification viewed from the polishing surface side. In the description of the modified example, the same reference numerals as those used in the above-described embodiment are used for convenience of description.

  FIG. 4 shows an example in which four annular grooves 19 are arranged on the polishing surface 9 so as to contact each other. In this modification, one semi-annular groove 19a, 19b has one connecting portion with the other semi-annular grooves 19a, 19b.

  FIG. 5 shows a polishing pad having four annular grooves 19, similar to the example shown in FIG. 4. In this example, four annular grooves 19 extend to the center of the polishing surface 9, and adjacent annular grooves 19 intersect at two places. Accordingly, in this example, one semi-annular groove 19a, 19b has two connecting portions with the other semi-annular grooves 19a, 19b.

  FIG. 6 shows an example in which eight annular grooves 19 are arranged on the polishing surface 9 at an angular interval of 45 degrees. In this modification, in one semi-annular groove 19a, 19b, there are three connecting portions with the other semi-annular grooves 19a, 19b.

  FIG. 7 shows an example in which eight annular grooves 19 are arranged on the doughnut-shaped polishing surface 9 at an angular interval of 45 degrees. In this example, the vicinity of the center of the polishing surface of the polishing pad shown in FIG. 6 is cut out so as to match the shape of the polishing apparatus so that the annular groove 19 opens toward the center opening of the polishing surface 9. In this example, one semi-annular groove 19a, 19b has two connecting portions with other semi-annular grooves 19a, 19b.

  FIG. 8 shows an example in which eight annular grooves 19 are arranged on the doughnut-shaped polishing surface 9 at an angular interval of 45 degrees. In this example, the annular grooves 19 are arranged so as to intersect in the vicinity of the center of the polishing surface 9, and then, the vicinity of the center of the polishing pad is cut out to form the donut-shaped polishing surface 9. Also in this example, the annular groove 19 opens toward the center opening of the polishing surface 9. In this example, one semi-annular groove 19a has two connecting portions with the other semi-annular grooves 19a and 19b.

  Thus, even with the polishing pad according to the modification, the retention of the polishing slurry by the polishing pad 7 can be improved, and the consumption of the polishing slurry can be suppressed. Moreover, it can suppress that the fluidity | liquidity of polishing slurry falls by reducing the number of the connection parts of semi-annular groove 19a, 19b.

  Further, even with the polishing pad according to the modified example, the retention of the polishing slurry by the polishing pad 7 can be improved, and the consumption of the polishing slurry can be suppressed. In addition, regarding the number of connecting portions, it is conceivable to increase the number of connecting portions by giving priority to the dispersibility of the polishing slurry with respect to the entire polishing surface. However, if the connecting portions are excessively provided, the flatness of the polishing surface is deteriorated or the polishing is performed. There is a risk of reducing the fluidity of the slurry. For this reason, it can suppress that the fluidity | liquidity of polishing slurry falls, ensuring the dispersibility of polishing slurry by making the number of the connection parts of semi-annular groove | channels 19a and 19b into 4 or less.

7 Polishing pad 9 Polishing surface 19 Annular groove

Claims (2)

A polishing pad having a circular polishing surface,
It has a plurality of annular grooves that draw an oval shape,
The polishing pad, wherein the annular groove is disposed so that a minor axis thereof is disposed in a radial direction of the polishing surface, and one end of the minor axis is overlapped with a circumference of the circular polishing surface.   Each of the plurality of annular grooves has a connecting portion connected to another annular groove in a curved portion extending from one end to the other end of the short axis, and the number of the connecting portions is four or less. The polishing pad according to claim 1, wherein the polishing pad is provided.

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