Conditioner for a polishing pad and method therefor

• US 5,456,627 A
• Filed: 12/20/1993
• Issued: 10/10/1995
• Est. Priority Date: 12/20/1993
• Status: Expired due to Term

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: Westech Systems, Inc. (Speedfam Co., Ltd)
• Inventors: Sanford, James E., Rice, Richard B., Baca, John G., Ong, Glen, Modi, Parag S., Schultz, Stephen C., Jackson, Paul D.
• Primary Examiner(s): Lavinder, Jack W.
• Application Number:
  US08/148,906
• Time in Patent Office: 659 Days
• Field of Search: 51/262 A, 51/325, 51/165.71, 51/165.77, 51/165.8, 51/5 D, 51/165.74, 451/65, 451/72, 451/56, 451/287, 451/288, 451/289, 451/290, 451/1, 451/5, 451/24, 451/26, 451/57, 451/63, 451/67
• US Class Current: 451/11
• CPC Class Codes: B24B 49/18 taking regard of the presence of dressing tools
• CPC Class Codes: B24B 53/017 Devices or means for dressing, cleaning or otherwise conditioning lapping tools

Abstract

An axially rotating circular polishing pad is conditioned by a rotating end effector that has an abrasion disc in contact with a polishing surface of the pad. The end effector moves along a radius of the polishing pad surface at a velocity that varies to compensate for locations on the polishing pad surface having linear velocities that are directly related to their respective radii. A desired contact force is maintained between the end effector and the polishing pad surface.

Claims

1. An apparatus for conditioning a polishing surface of a pad that is rotatable about a pad axis, comprising:

end effector means for contacting said polishing surface;

arm means coupled to said end effector means for moving said end effector means along a radial line passing through said pad axis; and

programming means coupled to said arm means for moving said end effector means across said polishing surface of said pad at a programmable rate to obtain uniform conditioning of said polishing surface of said pad.

2. An apparatus according to claim 1 further comprising:

abrasive disc means coupled to said end effector means for contacting said polishing surface of said pad;

said abrasive disc means rotating about a disc axis and simultaneously moving with said end effector means along said radial line passing through said pad axis.

3. An apparatus according to claim 2, said programming means further comprising rate means for controlling the rate of movement along a radial line of said end effector so that the linear velocity of said abrasion disc relative to said polishing surface of said pad remains constant to produce uniform conditioning.

4. An apparatus according to claim 3, further comprising:

force means coupled to said end effector means for programmably controlling the contact force applied by said abrasion disc on said polishing surface of said pad.

5. An apparatus according to claim 4, said force means further comprising:

controller means for providing a high gain amplifier having a differential input and an output;

computer means coupled to said differential input for generating a signal proportional to a programmed level of contact force;

transducer means coupled to said differential input for generating a signal proportional to the actual level of contact force applied by said abrasion disc on said polishing surface of said pad; and

actuator means coupled to said output of said controller means and operably coupled to said end effector means for moving said end effector means in the direction required to cause said actual level of contact force to be equal to programmed level of contact force.

6. An apparatus according to claim 1, said arm means further comprising:

lead screw means coupled to said end effector means for providing transverse movement to said end effector means; and

rotational means for axially rotating said lead screw means.

7. An apparatus according to claim 6, said arm means further comprising:

cantilever arm means coupled to a mounting end and containing said lead screw means and said rotational means for rotating around said mounting end to position said end effector means to allow movement along a radial line passing through said pad axis.

8. An apparatus according to claim 6, said rotational means further comprising a servomotor coupled to said lead screw means and a resolver coupled to said servomotor.

9. A method for conditioning a polishing surface of a pad that is rotatable about a pad axis, comprising the steps of:

providing end effector means for contacting said polishing surface;

providing arm means coupled to said end effector means for moving said end effector means along a radial line passing through said pad axis; and

providing programming means coupled to said arm means for moving said end effector means across said polishing surface of said pad at a programmable rate to obtain uniform conditioning of said polishing surface of said pad.

10. The method according to claim 9 further comprising the step of:

providing abrasive disc means coupled to said end effector means for contacting said polishing surface of said pad;

said abrasive disc means rotating about a disc axis and simultaneously moving with said end effector means along said radial line passing through said pad axis.

11. The method according to claim 10, said programming means further comprising rate means for controlling the rate of movement along a radial line of said end effector so that the linear velocity of said abrasion disc relative to said polishing surface of said pad remains constant to produce uniform conditioning.

12. The method according to claim 11, further comprising the step of:

providing force means coupled to said end effector means for programmably controlling the contact force applied by said abrasion disc on said polishing surface of said pad.

13. The method according to claim 12, said step of providing force means further comprising the steps of:

providing controller means for providing a high gain amplifier having a differential input and an output;

providing computer means coupled to said differential input for generating a signal proportional to a programmed level of contact force;

providing transducer means coupled to said differential input for generating a signal proportional to the actual level of contact force applied by said abrasion disc on said polishing surface of said pad; and

providing actuator means coupled to said output of said controller means and operably coupled to said end effector means for moving said end effector means in the direction required to cause said actual level of contact force to be equal to said programmed level of contact force.

14. The method according to claim 9, said arm means further comprising:

lead screw means coupled to said end effector means for providing transverse movement to said end effector means; and

rotational means for axially rotating said lead screw means.

15. The method according to claim 14, said arm means further comprising:

cantilever arm means coupled to a mounting end and containing said lead screw means and said rotational means for rotating around said mounting end to position said end effector means to allow movement along a radial line passing through said pad axis.

16. The method according to claim 15, said rotational means further comprising a servomotor coupled to said lead screw means and a resolver coupled to said servomotor.