Monitoring a Discharge in a Plasma Process

• US 20160217975A1
• Filed: 04/01/2016
• Published: 07/28/2016
• Est. Priority Date: 10/01/2013
• Status: Active Grant

• Current Assignee: TRUMPF Hüttinger GmbH + Co. KG (Trumpf GmbH + Company KG)
• Original Assignee: TRUMPF Hüttinger GmbH + Co. KG (Trumpf GmbH + Company KG)
• Inventors: Leypold, Daniel, Wunn, Fabian, Richter, Ulrich
• Granted Patent: US 10,181,392 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 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: H01J 37/32009 Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources plasma generation in general H05H1/24
• CPC Class Codes: H01J 37/32917 Plasma diagnostics
• CPC Class Codes: H01J 37/32926 Software, data control or modelling
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01J 37/32944 Arc detection

Abstract

Devices and methods for monitoring a discharge in a plasma process are provided. An example method includes detecting at least a first signal path of at least one plasma supply signal within at least a first time range within at least one period of the plasma supply signal, detecting at least a second signal path of the at least one plasma supply signal within at least a second time range which is at the point corresponding to the first time range in at least one other period of the plasma supply signal, and generating an identification signal if the second signal path deviates by at least a distance from the first signal path. The distance has a minimum time difference and a minimum signal amplitude difference. The method enables to identify arcs in a very reliable and very rapid manner.

Claims

1. A plasma discharge monitor comprising:

a signal detector responsive to

at least a first signal path of at least one plasma supply signal within at least a first time range within at least one period of the plasma supply signal, and

at least a second signal path of at least one plasma supply signal within at least a second time range located at one or more points corresponding to the first time range in at least one other period of the plasma supply signal; and

an identification signal generator configured to generate an identification signal if the second signal path deviates by at least a distance from the first signal path, wherein the distance has a minimum time difference and a minimum signal amplitude difference.

2. The monitor of claim 1, wherein the identification signal generator is configured such that the distance is

the minimum time difference as a first minimum distance from the first signal path in a time direction, and

the minimum signal amplitude difference as a second minimum distance from the first signal path in a signal amplitude direction.

3. The monitor of claim 1, further comprising at least one of:

an input interface for specifying the minimum time difference and the minimum signal amplitude difference, or

an input interface for specifying a value for establishing a flowing interval.

4. The monitor of claim 1, wherein the signal detector has an analog-digital converter (ABC) that has a temporal resolution no less than 10 megasamples per second and an amplitude resolution no less than 8 bit.

5. The monitor of claim 1, wherein the identification signal generator is accommodated in a programmable logic device (PLD).

6. The monitor of claim 1, wherein the identification signal generator is configured to:

establish a threshold value line from the first signal path based on the distance, and

generate the identification signal when the second signal path reaches the threshold value line.

7. The monitor of claim 6, wherein the identification signal generator is configured to establish the threshold value line such that the threshold value line has

the minimum time difference as a first minimum distance from the first signal path in a time direction, and

the minimum signal amplitude difference as a second minimum distance from the first signal path in a signal amplitude direction.

8. The monitor of claim 6, wherein the identification signal generator is configured to establish the threshold value line by one of:

adding the minimum time difference and the minimum signal amplitude difference to the first signal path, and

subtracting the minimum time difference and the minimum signal amplitude difference from the first signal path.

9. A method of monitoring a discharge in a plasma process, comprising:

detecting at least a first signal path of at least one plasma supply signal within at least a first time range within at least one period of the plasma supply signal;

detecting at least a second signal path of at least one plasma supply signal within at least a second time range located at one or more points corresponding to the first time range in at least one other period of the plasma supply signal; and

generating an identification signal if the second signal path deviates by at least a distance from the first signal path, wherein the distance has a minimum time difference and a minimum signal amplitude difference.

10. The method of claim 9, further comprising:

establishing the distance by carrying out a calculation from the first signal path, the minimum time difference, and the minimum signal amplitude difference, such that the distance has at least the minimum time difference in a time direction and at least the minimum signal amplitude difference in a signal amplitude direction.

11. The method of claim 9, wherein at least one of the minimum time difference or the minimum signal amplitude difference is predetermined by a user.

12. The method of claim 9, further comprising:

establishing a threshold value line from the first signal path based on the distance; and

generating the identification signal if the second signal path reaches the threshold value line.

13. The method of claim 12, wherein establishing the threshold value line comprises one of:

adding the minimum time difference and the minimum signal amplitude difference to the first signal path, and

subtracting the minimum time difference and the minimum signal amplitude difference from the first signal path.

14. The method of claim 12, wherein establishing the threshold value line comprises:

carrying out a calculation from the first signal path, the minimum time difference, and the minimum signal amplitude difference, such that the threshold value line has at least the minimum time difference as a first minimum distance from the first signal path in a time direction and at least the minimum signal amplitude difference as a second minimum distance from the first signal path in a signal amplitude direction.

15. The method of claim 9, wherein at least one of the minimum time difference or the minimum signal amplitude difference is predetermined by a user.

16. A plasma process system comprising:

a power generator configured to supply power to a plasma process with a periodically changing output signal of the power generator; and

a plasma discharge monitor for monitoring a discharge in the plasma process, comprising;

a signal detector responsive to

at least a first signal path of at least one plasma supply signal within at least a first time range within at least one period of the plasma supply signal, and

at least a second signal path of at least one plasma supply signal within at least a second time range located at one or more points corresponding to the first time range in at least one other period of the plasma supply signal; and

an identification signal generator configured to generate an identification signal if the second signal path deviates by at least a distance from the first signal path, wherein the distance has a minimum time difference and a minimum signal amplitude difference.

17. The plasma process system of claim 16, wherein the identification signal generator is configured to:

establish a threshold value line from the first signal path based on the distance, and

generate the identification signal when the second signal path reaches the threshold value line.

18. The plasma process system of claim 16, wherein the power generator is a free-running mid-frequency generator.

19. The plasma process system of claim 16, wherein the power generator has a bridge circuit for producing an alternating voltage.

20. The plasma process system of claim 16, wherein the signal detector is configured to measure a voltage at each of the electrodes of the plasma process with a respective measurement data detection device with respect to a reference earth.