METHOD OF MONITORING A DRESSING PROCESS AND POLISHING APPARATUS

• US 20140065931A1
• Filed: 08/27/2013
• Published: 03/06/2014
• Est. Priority Date: 08/28/2012
• Status: Active Grant

• Current Assignee: Ebara Corporation
• Original Assignee: Ebara Corporation
• Inventors: SHINOZAKI, Hiroyuki
• Granted Patent: US 9,808,908 B2
• Time in Patent Office: Days
• US Class Current: 451/56
• CPC Class Codes: B24B 49/16 taking regard of the load
• CPC Class Codes: B24B 49/18 taking regard of the presence of dressing tools

Abstract

A method of monitoring dressing of a polishing pad is provided. The method includes: rotating a polishing table that supports the polishing pad; dressing the polishing pad by pressing a dresser against the polishing pad while causing the dresser to oscillate in a radial direction of the polishing pad; calculating a work coefficient representing a ratio of a frictional force between the dresser and the polishing pad to a force of pressing the dresser against the polishing pad; and monitoring dressing of the polishing pad based on the work coefficient.

Claims

1. A method of monitoring dressing of a polishing pad, said method comprising:

rotating a polishing table that supports the polishing pad;

dressing the polishing pad by pressing a dresser against the polishing pad while causing the dresser to oscillate in a radial direction of the polishing pad;

calculating a work coefficient representing a ratio of a frictional force between the dresser and the polishing pad to a force of pressing the dresser against the polishing pad; and

monitoring dressing of the polishing pad based on the work coefficient.

2. The method according to claim 1, wherein the work coefficient is calculated from a torque of a table motor for rotating the polishing table, the force of pressing the dresser against the polishing pad, and a distance from a center of rotation of the polishing table to the dresser.

3. The method according to claim 2, wherein the work coefficient is given by

Z=(Tt−

Tt₀)/(DF*St)

where Z is the work coefficient, Tt is the torque of the table motor when the dresser is dressing the polishing pad, Tt₀ is an initial torque of the table motor before the dresser is brought into contact with the polishing pad, DF is the force of pressing the dresser against the polishing pad, and St is the distance from the center of rotation of the polishing table to the dresser.

4. The method according to claim 1, further comprising:

detecting a failure of dressing of the polishing pad by comparing the work coefficient with a predetermined threshold value.

5. The method according to claim 4, further comprising:

describing a position of the dresser at which the work coefficient exceeds the predetermined threshold value on a two-dimensional surface defined on the polishing pad.

6. The method according to claim 1, further comprising:

detecting a failure of dressing of the polishing pad by comparing an amount of change in the work coefficient per unit time with a predetermined threshold value.

7. The method according to claim 6, further comprising:

describing a position of the dresser at which the amount of change in the work coefficient per unit time exceeds the predetermined threshold value on a two-dimensional surface defined on the polishing pad.

8. The method according to claim 1, further comprising:

determining a remaining life of the dresser based on the work coefficient.

9. A polishing apparatus for polishing a substrate, comprising:

a polishing table that supports a polishing pad;

a table motor configured to rotate the polishing table;

a dresser configured to dress the polishing pad;

a swing motor configured to cause the dresser to oscillate in a radial direction of the polishing pad;

a pressing device configured to press the dresser against the polishing pad; and

a pad monitoring device configured to monitor dressing of the polishing pad, the pad monitoring device being configured to

calculate a work coefficient representing a ratio of a frictional force between the dresser and the polishing pad to a force of pressing the dresser against the polishing pad, and

monitor dressing of the polishing pad based on the work coefficient.

10. The polishing apparatus according to claim 9, wherein the pad monitoring device is configured to calculate the work coefficient from a torque of the table motor, the force of pressing the dresser against the polishing pad, and a distance from a center of rotation of the polishing table to the dresser.

11. The polishing apparatus according to claim 10, wherein the work coefficient is given by

Z=(Tt−

Tt₀)/(DF*St)

where Z is the work coefficient, Tt is the torque of the table motor when the dresser is dressing the polishing pad, Tt₀ is an initial torque of the table motor before the dresser is brought into contact with the polishing pad, DF is the force of pressing the dresser against the polishing pad, and St is the distance from the center of rotation of the polishing table to the dresser.

12. The polishing apparatus according to claim 9, wherein the pad monitoring device is configured to detect a failure of dressing of the polishing pad by comparing the work coefficient with a predetermined threshold value.

13. The polishing apparatus according to claim 12, wherein the pad monitoring device is configured to describe a position of the dresser at which the work coefficient exceeds the predetermined threshold value on a two-dimensional surface defined on the polishing pad.

14. The polishing apparatus according to claim 9, wherein the pad monitoring device is configured to detect a failure of dressing of the polishing pad by comparing an amount of change in the work coefficient per unit time with a predetermined threshold value.

15. The polishing apparatus according to claim 14, wherein the pad monitoring device is configured to describe a position of the dresser at which the amount of change in the work coefficient per unit time exceeds the predetermined threshold value on a two-dimensional surface defined on the polishing pad.

16. The polishing apparatus according to claim 9, wherein the pad monitoring device is configured to determine a remaining life of the dresser based on the work coefficient.