JP6121284B2 - Polishing equipment - Google Patents

Description

  The present invention relates to a polishing apparatus for polishing a plate workpiece.

  In a polishing apparatus that polishes a plate-like workpiece such as a wafer, polishing is performed by holding the plate-like workpiece on a holding surface of a holding table and pressing a polishing pad mounted on a polishing unit against the plate-like workpiece (for example, , See Patent Document 1).

Japanese Patent Laid-Open No. 2003-311614

  In such a polishing apparatus, the entire surface of the plate-shaped workpiece is in contact with the polishing pad in the same manner, and the vicinity of the center of the plate-shaped workpiece can be polished, and the rotation axis of the polishing pad and the rotation shaft of the holding table are connected. They are staggered.

  However, when the size or material of the plate-like workpiece changes, it is necessary to change settings such as the number of revolutions of the polishing pad, the number of revolutions of the holding table, the polishing load, and the positional relationship between the polishing pad and the holding table. When these settings change, the condition that the holding surface of the holding table and the polishing surface of the polishing pad become parallel also changes, so it is difficult to maintain the holding surface of the holding table and the polishing surface of the polishing pad in parallel. . If the holding surface of the holding table and the polishing surface of the polishing pad are not maintained in parallel during the polishing process, rippled polishing spots (a slight difference in thickness occurring in the radial direction) are generated on the polished plate-like workpiece. There is a case.

  The present invention has been considered in view of such problems, and by maintaining the holding surface of the holding table and the polishing surface of the polishing pad in parallel during the polishing process, the flatness of the surface to be polished of the plate-like workpiece is determined. The purpose is to prevent the occurrence of polishing spots.

  A polishing apparatus according to the present invention includes a holding table for holding a plate-like workpiece on a holding surface, a polishing unit on which a polishing pad for polishing the plate-like workpiece held on the holding surface is rotatably mounted, and the polishing unit And a polishing feed means for relatively approaching and separating the holding table, and the polishing pad on the plate-like work held by the holding table by the polishing feed means bringing the polishing means and the holding table close to each other Controls three or more load sensors for detecting a polishing load pressed by the pressure, an inclination adjusting means for adjusting an inclination between the polishing surface of the polishing pad and the holding surface of the holding table, and the inclination adjusting means. Each load sensor is arranged at regular vertices of a regular polygon whose center of gravity is the center of the holding table, and is detected by each load sensor during the polishing process. Research As the load is equalized, the control unit controls the-out adjustment means inclined.

  According to the polishing apparatus of the present invention, since the control means controls the inclination adjusting means so that the polishing load detected by each load sensor is equalized during polishing, the number of rotations of the polishing pad and the rotation of the holding table are controlled. Even when the setting such as the number, the polishing load, and the positional relationship between the polishing pad and the holding table is changed, the holding surface of the holding table and the polishing surface of the polishing pad can be maintained in parallel. Thereby, the flatness of the to-be-polished surface of a plate-shaped workpiece | work can be improved, and generation | occurrence | production of a polishing spot can be prevented.

The front view and top view showing a polish device. The graph which shows the change of the position of grinding | polishing feed, grinding | polishing load, and the support position by a support means.

  A polishing apparatus 10 shown in FIG. 1 includes a base 11, a holding table 12 that holds a plate-like workpiece 20, a polishing means 13 that polishes the plate-like workpiece 20, and a polishing feed that moves the polishing means 13 in ± Z directions. Means 14, three support means 15a-15c for supporting the holding table 12, three load sensors 16a-16c for measuring the polishing load, inclination adjusting means 19a-19c for adjusting the inclination of the holding table 12, and inclination And a control unit 17 that controls the adjusting means 19a to 19c.

  The holding table 12 is, for example, a chuck table, and sucks and holds the plate-like workpiece 20 placed on the holding surface 121. The holding table 12 is rotatable around a rotation axis 129 parallel to the ± Z direction.

  The polishing means 13 has a polishing pad 30 attached to the tip, and rotates the polishing pad 30 around a rotation axis 139 parallel to the ± Z direction, thereby rotating and holding the plate-like workpiece 20 held by the holding table 12. To polish. The polishing method may be, for example, chemical mechanical polishing (CMP) or dry polishing. The polishing pad 30 is made of, for example, cloth or resin. The structure which the abrasive pad 30 contains an abrasive grain may be sufficient, and the structure which supplies an abrasive grain from the outside may be sufficient. The rotating shaft 139 of the polishing pad 30 and the rotating shaft 129 of the holding table 12 are separated from each other. The diameter of the polishing pad 30 is larger than the diameter of the plate-like workpiece 20, and the polishing surface (surface in the −Z direction) of the polishing pad 30 is entirely applied to the surface to be polished (surface in the + Z direction) of the plate-like workpiece 20 during polishing. ) Come into contact.

  The polishing feed unit 14 includes, for example, a ball screw mechanism, and moves the polishing unit 13 in the ± Z directions in accordance with instructions from the control unit 17. When the polishing feed means 14 moves the polishing means 13 in the + Z direction, the holding table 12 and the polishing means 13 are relatively separated from each other, and when the polishing feed means 14 moves the polishing means 13 in the −Z direction, the holding table. 12 and the polishing means 13 are relatively close to each other.

  The three support means 15a to 15c are arranged at equal distances in directions away from each other by 120 degrees with the rotation axis 129 of the holding table 12 as the center. Each support means 15a-15c is supporting the holding table 12 via the inclination adjustment means 19a-19c. The inclination adjusting means 19a to 19c move the positions where the support means 15a to 15c support the holding table 12 with, for example, screws or levers in the ± Z directions, thereby allowing the holding surface 121 of the holding table 12 and the polishing pad 30 to move. Adjust the tilt between the polished surface.

  Each of the load sensors 16 a to 16 c is disposed between the support means 15 a to 15 c and the base 11. Accordingly, the three load sensors 16 a to 16 c are arranged at equal intervals from each other at a position equidistant from the rotation shaft 129 of the holding table 12. The triangle whose apex is the position where the three load sensors 16a to 16c detect the polishing load is an equilateral triangle. The equilateral triangle is perpendicular to the rotation axis 129, and the center of gravity is located on the rotation axis 129. When the polishing feed means 14 moves the polishing means 13 in the −Z direction so that the polishing surface of the polishing pad 30 comes into contact with the surface to be polished of the plate-like workpiece 20 and the polishing pad 30 presses the plate-like workpiece 20, the pressure is increased. Are detected as polishing loads by the load sensors 16a to 16c.

The control unit 17 controls the inclination adjusting means 19a to 19c so that the polishing loads detected by the load sensors 16a to 16c are equalized.
For example, when the polishing load detected by the load sensor 16a is smaller than the polishing loads detected by the other two load sensors 16b and 16c, the control unit 17 applies the support means 15a on which the load sensor 16a is disposed. By controlling the connected inclination adjusting means 19a, the position where the support means 15a supports the holding table 12 is moved in the + Z direction. As a result, the distance between the holding surface 121 of the holding table 12 and the polishing surface of the polishing pad 30 at a position close to the support means 15a is reduced, so that the polishing load detected by the load sensor 16a is increased.
On the other hand, when the polishing load detected by the load sensor 16a is larger than the polishing loads detected by the other two load sensors 16b and 16c, the controller 17 supports the support means 15a in which the load sensor 16a is disposed. The tilt adjusting means 19a connected to is controlled to move the position where the support means 15a supports the holding table 12 in the -Z direction. As a result, the distance between the holding surface 121 of the holding table 12 and the polishing surface of the polishing pad 30 at a position close to the support means 15a increases, so that the polishing load detected by the load sensor 16a decreases.

  The diameter of the polishing pad 30 is larger than the diameter of the plate-like workpiece 20, and the polishing surface of the polishing pad 30 is always in contact with the entire surface to be polished of the plate-like workpiece 20 during polishing. This is a different point from a grinding apparatus that is performing a grinding process in which the grinding surface of the grinding wheel is not in contact with the entire surface to be ground of the plate workpiece 20. Therefore, when the inclination between the holding surface 121 of the holding table 12 and the polishing surface of the polishing pad 30 is adjusted so that the polishing load of each sensor becomes equal, the polishing of the holding surface 121 of the holding table 12 and the polishing pad 30 is performed. The plane becomes parallel.

  Further, the control unit 17 controls the inclination adjusting means 19a to 19c so that the polishing load detected by the load sensors 16a to 16c during the polishing process is within a predetermined load range. For example, when the polishing load is larger than the upper limit of the load range, the control unit 17 controls the inclination adjusting units 19a to 19c to move the positions at which the support units 15a to 15c support the holding table 12 in the −Z direction. Conversely, when the polishing load is smaller than the lower limit of the load range, the control unit 17 controls the inclination adjusting means 19a to 19c to move the positions at which the support means 15a to 15c support the holding table 12 in the + Z direction.

  In FIG. 2, a position 61 is a position in the ± Z direction when the polishing feed means 14 moves the polishing means 13, and the polishing loads 62a to 62c are polishing loads detected by the load sensors 16a to 16c, respectively. Yes, the support positions 63a to 63c are support positions in the ± Z direction where the support means 15a to 15c adjusted by the inclination adjustment means 19a to 19c support the holding table 12, respectively.

  At the start of polishing, the polishing means 13 retracted in the + Z direction starts to move the polishing feed means 14 in the −Z direction at time 41. At this time, the polishing surface of the polishing pad 30 attached to the polishing means 13 and the holding surface 121 of the holding table 12 are not parallel, and the + X direction side across the Y axis is the polishing surface of the polishing pad 30. It is assumed that the distance between the holding surface 121 of the holding table 12 is close and the distance between the polishing surface of the polishing pad 30 and the holding surface 121 of the holding table 12 is long on the −X direction side.

  In that case, on the + X direction side, the polishing surface of the polishing pad 30 and the surface to be polished of the plate-like workpiece 20 first come into contact with each other. For this reason, when the load sensor 16c detects the polishing load at time 42, the other load sensors 16a and 16b have not detected the polishing load yet. Since the polishing load detected by the load sensor 16c is larger than the polishing loads detected by the other two load sensors 16a and 16b, the control unit 17 controls the inclination adjusting means 19c and the holding table 12 by the support means 15c. Is moved in the −Z direction.

  At time 43, the load sensor 16a starts to detect the polishing load. However, since the polishing load detected by the load sensor 16c is still larger than the polishing loads detected by the other two load sensors 16a and 16b, the control unit 17 controls the tilt adjusting means 19c to further move the support position of the holding table 12 by the support means 15c in the -Z direction. Further, only the load sensor 16b has not yet detected the polishing load, and the polishing load detected by the load sensor 16b is smaller than the polishing load detected by the other two load sensors 16a and 16c. The tilt adjusting means 19b is controlled to move the support position of the holding table 12 by the support means 15b in the + Z direction.

  At time 44, when the load sensor 16b starts to detect the polishing load, if the polishing loads detected by the two load sensors 16a and 16c are substantially equal, only the polishing load detected by the load sensor 16b is obtained. Since it is smaller than the polishing load detected by the other two load sensors 16a and 16c, the control unit 17 controls the inclination adjusting means 19b and further moves the support position of the holding table 12 by the support means 15b in the + Z direction.

  If the polishing loads detected by the three load sensors 16a to 16c become the same at time 45, the polishing surface of the polishing pad 30 and the holding surface 121 of the holding table 12 are thereby made parallel. In this way, the polishing surface of the polishing pad 30 and the holding surface 121 of the holding table 12 become parallel at a very early stage when polishing is started.

  During the polishing process, the control unit 17 always monitors the polishing load detected by the three load sensors 16a to 16c. When the three polishing loads become unequal, the control unit 17 immediately controls the inclination adjusting means 19a to 19c to change the support position of the supporting means corresponding to the polishing load that is out of balance, and the three polishing loads. Make the load equal. Thus, the polishing surface of the polishing pad 30 and the holding surface 121 of the holding table 12 are always kept parallel during the polishing process. For this reason, the flatness of the surface to be polished of the plate-like workpiece 20 held on the holding surface 121 can be increased, and the occurrence of polishing spots can be prevented.

  In addition, when the polishing load detected by each of the load sensors 16a to 16c reaches the upper limit 512 of the appropriate load range 51 during the polishing process, each of the support means 15a to 15c is controlled by controlling the inclination adjusting means 19a to 19c. Similarly, the support position of the holding table 12 is moved in the −Z direction. As a result, the distance between the polishing surface of the polishing pad 30 and the holding surface 121 of the holding table 12 is increased while the polishing surface of the polishing pad 30 and the holding surface 121 of the holding table 12 are kept parallel. Therefore, the polishing load detected by each of the load sensors 16a to 16c is similarly reduced and falls within the appropriate load range 51.

  On the other hand, when the polishing load detected by each of the load sensors 16a to 16c reaches the lower limit 511 of the appropriate load range 51 during the polishing process, each of the support adjusting units 15a is controlled by controlling the inclination adjusting units 19a to 19c. Similarly, the support position of the holding table 12 by 15c is moved in the + Z direction. As a result, the distance between the polishing surface of the polishing pad 30 and the holding surface 121 of the holding table 12 is reduced while keeping the polishing surface of the polishing pad 30 parallel to the holding surface 121 of the holding table 12. Therefore, the polishing load detected by each of the load sensors 16 a to 16 c increases in the same manner and falls within the appropriate load range 51.

The embodiment described above is an example, and the present invention is not limited to this.
For example, the polishing feed means 14 may be anything that relatively moves the holding table 12 and the polishing means 13 closer to and away from each other, and does not move the polishing means 13 but moves the holding table 12. Alternatively, both the holding table 12 and the polishing means 13 may be moved in the ± Z direction.
Moreover, the load sensors 16a-16c should just be arrange | positioned rotationally symmetrically centering | focusing on the rotating shaft 129 of the holding table 12, and not only three but four or more may be sufficient.
Furthermore, the inclination adjusting means 19a to 19c may be any means that adjusts the inclination between the holding surface 121 of the holding table 12 and the polishing surface of the polishing pad 30, and does not adjust the inclination of the holding table 12, The structure which adjusts the inclination of the grinding | polishing means 13 may be sufficient, and the structure which adjusts the inclination of both the holding table 12 and the grinding | polishing means 13 may be sufficient.
The controller 17 is configured not to control the inclination adjusting means 19a to 19c but to adjust the polishing feed amount by controlling the polishing feed means 14 so that the polishing load falls within the load range. Also good.

10 polishing apparatus, 11 base, 12 holding table, 121 holding surface,
129, 139 rotation axis,
13 polishing means, 14 polishing feeding means, 15 support means, 16 load sensor,
17 control part, 18 judgment part, 19 inclination adjustment means, 20 plate-like workpiece,
30 polishing pad, 41, 42, 43, 44, 45, 46 time,
51 proper load range, 511 lower limit, 512 upper limit,
61 position, 62 polishing load, 63 support position

Claims (1)

A holding table for holding a plate-like workpiece on the holding surface;
A polishing means on which a polishing pad for polishing the plate-like workpiece held on the holding surface is rotatably mounted;
Polishing feed means for relatively approaching and separating the polishing means and the holding table;
Three or more load sensors for detecting a polishing load by which the polishing pad is pressed against the plate-like workpiece held by the holding table by the polishing feeding unit approaching the polishing unit and the holding table;
An inclination adjusting means for adjusting an inclination between the polishing surface of the polishing pad and the holding surface of the holding table;
A control unit for controlling the inclination adjusting means;
In a polishing apparatus comprising:
Each load sensor is arranged at regular intervals at the vertices of a regular polygon whose center of gravity is the center of the holding table,
A polishing apparatus in which the control unit controls the inclination adjusting means so that the polishing load detected by each load sensor is equalized during polishing.

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