Application of wideband sampling for arc detection with a probabilistic model for quantitatively measuring arc events

• US 8,289,029 B2
• Filed: 07/18/2008
• Issued: 10/16/2012
• Est. Priority Date: 02/14/2008
• Status: Active Grant

• Current Assignee: MKS Instruments Incorporated
• Original Assignee: MKS Instruments Incorporated
• Inventors: Coumou, David J.
• Primary Examiner(s): Dole, Timothy J
• Application Number:
  US12/175,867
• Publication Number:
  US 20090207537A1
• Time in Patent Office: 1,551 Days
• Field of Search: 324/536
• US Class Current: 324/536
• CPC Class Codes: G01R 19/0061 Measuring currents of particle-beams, currents from electron multipliers, photocurrents, ion currents; Measuring in plasmas
• CPC Class Codes: G01R 21/01 in circuits having distributed constants G01R21/04, G01R21/07, G01R21/09, G01R21/12 take precedence
• CPC Class Codes: G01R 31/00 Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere measuring superconductive properties G01R33/1238; testing or measuring semiconductors or solid state devices during manufacture H01L22/00; testing line transmission systems H04B3/46
• CPC Class Codes: G01R 31/12 Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing G01R31/08, G01R31/327 and G01R31/72 take precedence; measuring in plasmas G01R19/0061; measuring dielectric constants G01R27/2617; ESD, EMC or EMP testing of circuits G01R31/002
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

An arc detection system for a plasma generation system includes a radio frequency (RF) sensor that generates first and second signals based on a respective electrical properties of (RF) power that is in communication with a plasma chamber. A correlation module generates an arc detect signal based on the first and second signals. The arc detect signal indicates whether an arc is occurring in the plasma chamber and is employed to vary an aspect of the RF power to extinguish the arc.

Claims

1. An arc detection system for a plasma generation system, comprising:

a radio frequency (RF) sensor that generates first and second signals based on a respective electrical properties of RF power that is in communication with a plasma chamber; and

an analysis module that generates an arc detect signal based on cross-correlating the first and second signals, wherein the arc detect signal indicates whether an arc is occurring in the plasma chamber and is employed to vary an aspect of the RF power to extinguish the arc, and that determines an estimated energy of the arc based on a correlation of the first and second signals.

2. The arc detection system of claim 1, wherein the analysis module comprises a subtraction module that subtracts signal levels from respective ones of the first and second signals.

3. The arc detection system of claim 1, wherein the analysis module comprises a window module that applies a window function to the first and second signals.

4. The arc detection system of claim 1, further comprising a probabilistic module that computes a probability of an arc event based on the arc detect signal.

5. The arc detection system of claim 4, wherein the probabilistic module employs a Baum-Welch algorithm to calculate a probabilistic model of the arc event.

6. The arc detection system of claim 5, wherein the probabilistic module employs a Viterbi algorithm to compute the probability of the arc event.

7. The arc detection system of claim 1, wherein the analysis module receives an enable signal that selectively enables generating the arc detect signal.

8. The arc detection system of claim 1, wherein further comprising an analog-to-digital (A/D) conversion module that digitizes the first and second signals.

9. The arc detection system of claim 1, wherein the RF sensor is a directional coupler and the first and second signals represent the forward power and reflected power, respectively, of the RF power.

10. The arc detection system of claim 1, wherein the RF sensor is a voltage/current (V/I) sensor and the first and second signals represent a voltage and current, respectively, of the RF power.

11. The arc detection system of claim 10, wherein the estimated energy of the arc is determined by multiplying a duration of the arc and a difference in a power estimate between during the arc and before the arc.

12. The arc detection system of claim 11, wherein the power estimate is determined by the equation:

13. An arc detection method for a plasma generation system, comprising:

generating first and second signals based on respective electrical properties of radio frequency (RF) power that is in communication with a plasma chamber;

generating an arc detect signal based on the first and second signals, wherein the arc detect signal indicates whether an arc is occurring in the plasma chamber;

employing the arc detect signal to vary an aspect of the RF power to extinguish the arc; and

generating an estimated energy of the arc based on a cross-correlation of the first and second signals.

14. The arc detection method of claim 13, further comprising subtracting signal levels from respective ones of the first and second signals.

15. The arc detection method of claim 13, further comprising applying a window function to the first and second signals.

16. The arc detection method of claim 13, further comprising computing a probability of an arc event based on the arc detect signal.

17. The arc detection method of claim 16, wherein the computing step further comprises employing a Baum-Welch algorithm to calculate a probabilistic model of the arc event.

18. The arc detection method of claim 17, wherein the computing step further comprises employing a Viterbi algorithm to compute the probability of the arc event.

19. The arc detection method of claim 13, further comprising receiving an enable signal that selectively enables generating the arc detect signal.

20. The arc detection method of claim 13, further comprising digitizing the first and second signals.

21. The arc detection method of claim 13, wherein the first and second signals represent the forward power and reflected power, respectively, of the RF power.

22. The arc detection method of claim 13, wherein the first and second signals represent a voltage and current, respectively, of the RF power.

23. The arc detection method of claim 22, wherein the estimated energy of the arc is determined by multiplying a duration of the arc and a difference in a power estimate between during the arc and before the arc.

24. The arc detection method of claim 23, wherein the power estimate is determined by the equation: