Method and apparatus for monitoring a polishing surface of a polishing pad used in polishing apparatus

Patent metadata

Field	Value
Publication number	US-9943943-B2
Application number	US-201615051928-A
Country	US
Kind code	B2
Filing date	Feb 24, 2016
Priority date	Jun 2, 2011
Publication date	Apr 17, 2018
Grant date	Apr 17, 2018

Abstract

A method is capable of monitoring the polishing surface of the polishing pad without removing the polishing pad from the polishing table. The method includes: conditioning the polishing surface of the polishing pad by causing a rotating dresser to oscillate on the polishing surface; measuring a height of the polishing surface when the conditioning of the polishing surface is performed; calculating a position of a measuring point of the height on a two-dimensional surface defined on the polishing surface; and repeating the measuring of the height of the polishing surface and the calculating of the position of the measuring point to create height distribution in the polishing surface.

First claim

What is claimed is:

1. A method of monitoring a polishing surface of a polishing pad for use in a polishing apparatus, said method comprising:
conditioning the polishing surface of the polishing pad by placing a rotating dresser on the polishing surface at a first conditioning position while keeping a dresser arm stationary, the rotating dresser being mounted at a distal end of a vertically movable dresser shaft extending vertically from the dresser arm;
determining a height of the polishing surface including measuring a displacement of a sensor target with a pad height sensor during said conditioning while the dresser arm is stationary for at least a preset time, the pad height sensor being secured to the dresser arm, and the sensor target being secured to the dresser shaft and being vertically movable together with the dresser shaft;
judging whether or not the determined height is below a target value; and
if the determined height is below the target value, moving the dresser arm until the dresser reaches a second conditioning position on the polishing pad.

2. The method according to claim 1 , further comprising:
before said conditioning of the polishing surface, measuring the height of an entirety of the polishing surface; and
determining the target value from a measurement result of the height of the entirety of the polishing surface.

3. The method according to claim 2 , further comprising:
after the target value is determined, moving the dresser arm until the dresser is located at the first conditioning position above the polishing surface,
wherein said conditioning comprises conditioning the polishing surface of the polishing pad by pressing the dresser against the polishing surface while rotating the polishing pad and the dresser.

4. The method according to claim 1 , further comprising:
if the determined height is not below the target value, not moving the dresser arm while the rotating dresser keeps conditioning the polishing surface.

5. The method according to claim 1 , further comprising:
after moving the dresser arm, judging whether or not the dresser has reached a preset conditioning end position on the dressing pad; and
if the dresser has reached the preset conditioning end position, terminating conditioning of the polishing surface.

6. The method according to claim 5 , further comprising:
if the dresser has not reached the preset conditioning end position, performing again said conditioning of the polishing surface for, said determining of the height of the polishing surface, and said judging whether or not the determined height is below the target value.

7. The method according to claim 1 , wherein said determining of the height of the polishing surface comprises determining a height of the polishing surface at a measuring point while calculating a position of the measuring point on a two-dimensional surface defined on the polishing surface.

8. The method according to claim 1 , wherein the sensor target is secured to the dresser shaft at a location between the rotating dresser and the dresser arm.

9. The method according to claim 1 , wherein the pad height sensor and the sensor target are located above the polishing pad.

10. A polishing apparatus capable of conditioning a polishing surface of a polishing pad, said apparatus comprising:
a rotatable dresser configured to condition the polishing surface of the polishing pad when the dresser is placed on the polishing surface;
a dresser arm supporting the dresser and configured to move the dresser in a radial direction of the polishing pad;
a vertically movable dresser shaft extending vertically from the dresser arm, the rotatable dresser being mounted at a distal end of the dresser shaft;
a sensor target secured to the dresser shaft and movable vertically together with the dresser shaft;
a pad height sensor secured to the dresser arm and configured to determine a height of the polishing surface by performing a process including measuring a displacement of the sensor target while the dresser arm is stationary for at least a preset time; and
a pad monitoring device configured to judge whether or not the determined height is below a target value; and
a motor configured to move the dresser arm until the dresser reaches a subsequent conditioning position on the polishing pad if the pad monitoring device has judged that the determined height is below the target value.

11. The polishing apparatus according to claim 10 , wherein the target value is determined from a measurement result of the height of an entirety of the polishing surface which is measured before the polishing surface is conditioned by the dresser.

12. The polishing apparatus according to claim 11 , wherein:
the motor is configured to move the dresser arm until the dresser is located at an initial conditioning position above the polishing surface after the target value is determined; and
the dresser is configured to rotate and press the polishing surface while the polishing pad is rotating to thereby condition the polishing surface of the polishing pad.

13. The polishing apparatus according to claim 10 , wherein the motor is configured not to move the dresser arm while the dresser keeps conditioning of the polishing surface, if the pad monitoring device has judged that the determined height is not below the target value.

14. The polishing apparatus according to claim 10 , wherein the dresser is configured to terminate conditioning of the polishing surface if the dresser has reached a preset conditioning end position on the polishing pad.

15. The polishing apparatus according to claim 14 , wherein if the dresser has not reached the preset conditioning end position, the dresser conditions the polishing surface again, the pad height sensor measures the height of the polishing surface again, and the pad monitoring device judges whether or not the determined height is below the target value again.

16. The polishing apparatus according to claim 10 , wherein the pad height sensor determines the height of the polishing surface at a measuring point while the pad monitoring device calculates a position of the measuring point on a two-dimensional surface defined on the polishing surface.

17. The polishing apparatus according to claim 10 , wherein the sensor target is secured to the dresser shaft at a location between the rotating dresser and the dresser arm.

18. The polishing apparatus according to claim 10 , wherein the pad height sensor and the sensor target are to be located above the polishing pad.

19. A method of monitoring a polishing surface of a polishing pad for use in a polishing apparatus, said method comprising:
conditioning the polishing surface of the polishing pad by placing a rotating dresser on the polishing surface at a first conditioning position while keeping a dresser arm stationary, the rotating dresser being mounted at a distal end of a vertically movable dresser shaft extending vertically from the dresser arm;
determining a vertical position of the polishing surface including measuring a displacement of a sensor target with a displacement sensor during said conditioning while the dresser arm is stationary for at least a preset time, the displacement sensor being secured to the dresser arm, and the sensor target being secured to the dresser shaft and being vertically movable together with the dresser shaft;
judging whether or not the determined vertical position is below a target value; and
if the determined vertical position is below the target value, moving the dresser arm unti

Assignees

• Ebara Corp

Inventors

• Shinozaki Hiroyuki
• Shimano Takahiro
• Imamura Akira
• Nakamura Akira

Classifications

• B24B37/042

  operating processes therefor · CPC title

• B24B49/02

  according to the instantaneous size and required size of the workpiece acted upon, the measuring or gauging being continuous or intermittent (B24B49/12 takes precedence) · CPC title

• B24B53/005

  Positioning devices for conditioning tools · CPC title

• B24B53/017

  Devices or means for dressing, cleaning or otherwise conditioning lapping tools · CPC title

• B24B53/08

  controlled by information means, e.g. patterns, templets, punched tapes or the like · CPC title