Arc Detection and Handling in Radio Frequency Power Applications

• US 20080156632A1
• Filed: 10/16/2007
• Published: 07/03/2008
• Est. Priority Date: 04/22/2005
• Status: Active Grant

• Current Assignee: AES Global Holdings Pte Ltd. (Advanced Energy Industries, Inc. (China))
• Original Assignee: Advanced Energy Industries Incorporated
• Inventors: Van Zyl, Gideon J.
• Granted Patent: US 7,761,247 B2
• Time in Patent Office: Days
• US Class Current: 204/164
• CPC Class Codes: H01J 2237/0206 Extinguishing, preventing or controlling unwanted discharges
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32174 Circuits specially adapted for controlling the RF discharge
• CPC Class Codes: H01L 21/67069 for drying etching

Abstract

A method and apparatus for detecting arcs in a plasma processing system is disclosed. In one embodiment the apparatus comprises an input to receive a measured value of a parameter related to power transfer from the RF power generator to a plasma load; arc detection circuitry that computes a dynamic boundary about the value of the parameter; and controller logic responsive to the arc detection circuitry, wherein the controller logic indicates an occurrence of an arc within the plasma load if a subsequent value of the parameter exceeds the dynamic boundary.

Claims

1. A method of delivering radio frequency power to a plasma load, comprising:

transferring radio frequency power to the plasma load;

computing a dynamic boundary corresponding to a first parameter representative of the power transferred to the plasma load;

computing a dynamic boundary corresponding to a second parameter representative of the power transferred to the plasma load;

measuring values of the first and second parameters; and

indicating the occurrence of an arc within the plasma load if at least one of the values of the first and second parameters exceeds the dynamic boundary corresponding to the parameter.

2. The method of claim 1, wherein the first parameter is a reflection coefficient.

3. The method of claim 1 wherein the second parameter is a reflection coefficient.

4. The method of claim 1 wherein at least one of the first and second parameters is a DC bias.

5. The method of claim 1 wherein the dynamic boundary is computed based upon a filtered value of the parameter.

6. The method of claim 1 wherein each of the dynamic boundaries include an upper limit and a lower limit.

7. The method of claim 1 wherein at least one of the dynamic boundaries is computed based upon a user-defined offset from the corresponding parameter.

8. The method of claim 1, including:

extinguishing the arc.

9. The method of claim 7 wherein extinguishing the arc includes interrupting power transfer to the load.

10. The method of claim 7 wherein the step of extinguishing the arc comprises reducing power transfer to the load.

11. The method of claim 7 wherein extinguishing the arc occurs during tuning of power transfer to the plasma load.

12. The method of claim 7, including:

holding the dynamic boundary constant during the step of extinguishing the arc.

13. An apparatus for detecting arcs in a plasma processing system, comprising:

an input to receive a measured value of a parameter related to power transfer from the RF power generator to a plasma load;

arc detection circuitry that computes a dynamic boundary about the value of the parameter; and

controller logic responsive to the arc detection circuitry, wherein the controller logic indicates an occurrence of an arc within the plasma load if a subsequent value of the parameter exceeds the dynamic boundary.

14. The system of claim 13 wherein the parameter is reflected power.

15. The system of claim 13 wherein the parameter is a DC bias.

16. The system of claim 13 wherein the arc detection circuitry computes the dynamic boundary based upon a filtered value of the parameter.

17. The system of claim 16 wherein the arc detection circuitry comprises a fast filter and a slow filter, and wherein the arc detection circuitry computes the dynamic boundary based upon the parameter as filtered by the slow filter and the controller logic indicates an occurrence of an arc if a subsequent value of the parameter as filtered by the fast filter exceeds the dynamic boundary.

18. The system of claim 13 wherein the arc detection circuitry computes the dynamic boundary based upon values of at least two parameters related to the power transfer from the RF power generator to the load.

19. The system of claim 13 wherein the dynamic boundary comprises an upper limit and a lower limit.

20. The system of claim 13 wherein the arc detection circuitry computes the dynamic boundary based upon a user-defined offset from the parameter.

21. The system of claim 13, further comprising a switch responsive to the controller logic that acts to extinguish the arc.

22. The system of claim 21 wherein the switch interrupts power transfer to the load to extinguish the arc.