Control systems employing deflection sensors to control clamping forces applied by electrostatic chucks, and related methods

Patent metadata

Field	Value
Publication number	US-9875923-B2
Application number	US-201615385441-A
Country	US
Kind code	B2
Filing date	Dec 20, 2016
Priority date	Nov 19, 2013
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

A control system that includes deflection sensors which can control clamping forces applied by electrostatic chucks, and related methods are disclosed. By using a sensor to determine a deflection of a workpiece supported by an electrostatic chuck, a control system may use the deflection measured to control a clamping force applied to the workpiece by the electrostatic chuck. The control system applies a clamping voltage to the electrostatic chuck so that the clamping force reaches and maintains a target clamping force. In this manner, the clamping force may secure the workpiece to the electrostatic chuck to enable manufacturing operations to be performed while preventing workpiece damage resulting from unnecessary higher values of the clamping force.

First claim

What is claimed is:

1. A control system, comprising:
an electrostatic chuck;
an interferometric sensor positioned to determine a deflection of a workpiece into at least one recess of the electrostatic chuck as the electrostatic chuck applies a clamping force to the workpiece, wherein at least a portion of the interferometric sensor is disposed at least partially within the at least one recess of the electrostatic chuck; and
a controller configured to:
determine a clamping force to apply to the workpiece based on the deflection that is determined; and
adjust a clamping voltage at the electrostatic chuck to apply the clamping force to the workpiece.

2. The control system of claim 1 , wherein the interferometric sensor is an interferometric displacement sensor.

3. The control system of claim 1 , wherein the at least a portion of the interferometric sensor is an end portion of an optical fiber.

4. The control system of claim 1 , wherein the electrostatic chuck comprises a plurality of mesas and the at least one recess of the electrostatic chuck is disposed between adjacent mesas of the plurality of mesas.

5. The control system of claim 4 , wherein the at least one recess has a width from 2 mm to 30 mm, wherein the width is defined by a distance between the adjacent mesas.

6. The control system of claim 4 , wherein the at least one recess has a depth from 50 microns to 700 microns, wherein the depth is defined by a height of the adjacent mesas.

7. The control system of claim 1 , wherein the interferometric sensor is configured to emit radiation to a surface of the workpiece and to measure the radiation reflected to determine the deflection.

8. The control system of claim 7 , wherein an end portion of an optical fiber is exposed to the at least one recess to receive a portion of the radiation which is reflected from the surface of the workpiece to determine the deflection of the workpiece.

9. A control system, comprising:
an electrostatic chuck comprising at least one recess and a plurality of mesas, wherein the at least one recess of the electrostatic chuck is disposed between adjacent mesas of the plurality of mesas;
an electrical current sensor comprising a first measurement electrode disposed within a first mesa of the adjacent mesas, the first measurement electrode configured to measure an induced current in a workpiece disposed on the electrostatic chuck; and
a controller configured to:
determine a deflection of the workpiece into the at least one recess as the electrostatic chuck applies a clamping force to the workpiece, wherein the deflection is determined based on the measured induced current;
determine a clamping force to apply to the workpiece based on the deflection that is determined; and
adjust a clamping voltage at the electrostatic chuck to apply the clamping force to the workpiece.

10. The control system of claim 9 , wherein the electrostatic chuck further comprises one or more power electrodes configured to apply the clamping voltage to the workpiece.

11. The control system of claim 10 , wherein the one or more power electrodes are electrically coupled to an alternating current power source.

12. The control system of claim 9 , wherein the electrical current sensor further comprises a second measurement electrode disposed with a second mesa of the adjacent mesas.

13. A control system, comprising:
an electrostatic chuck;
a sensor positioned to determine a deflection of a workpiece into at least one recess of the electrostatic chuck as the electrostatic chuck applies a clamping force to the workpiece, wherein the sensor comprises an end portion of an optical fiber that is configured to transmit radiation to the workpiece through the at least one recess, wherein the end portion of the optical fiber is located in the electrostatic chuck; and
a controller configured to:
determine a clamping force to apply to the workpiece based on the deflection that is determined; and
adjust a clamping voltage at the electrostatic chuck to apply the clamping force to the workpiece.

14. The control system of claim 13 , wherein the sensor comprises an interferometric displacement sensor.

15. The control system of claim 13 , wherein the electrostatic chuck comprises a plurality of mesas and the at least one recess of the electrostatic chuck is disposed between adjacent mesas of the plurality of mesas.

16. The control system of claim 15 , wherein the at least one recess has a width from 2 mm to 30 mm, wherein the width is defined by a distance between the adjacent mesas.

17. The control system of claim 15 , wherein the at least one recess has a depth from 50 microns to 700 microns, wherein the depth is defined by a height of the adjacent mesas.

18. The control system of claim 13 , wherein the sensor is configured to emit radiation to a surface of the workpiece and to measure the radiation reflected to determine the deflection.

19. The control system of claim 18 , wherein the end portion of the optical fiber is exposed to the at least one recess to receive a portion of the radiation which is reflected from the surface of the workpiece to determine the deflection of the workpiece.

Assignees

• Applied Materials Inc

Inventors

• Boyd Jr Wendell
• Parkhe Vijay D
• Busche Matthew James
• Makhratchev Konstantin
• Ono Masanori
• Thach Senh

Classifications

• H10P72/0616

  Monitoring of warpages, curvatures, damages, defects or the like · CPC title

• H10P72/722 Primary

  Details of electrostatic chucks · CPC title

• H01L21/6833 Primary

  Electricity · mapped topic

• H01L21/67288

  Electricity · mapped topic