DETERMINING HIGH FREQUENCY OPERATING PARAMETERS IN A PLASMA SYSTEM

• US 20100170640A1
• Filed: 01/22/2010
• Published: 07/08/2010
• Est. Priority Date: 07/23/2007
• Status: Active Grant

• Current Assignee: Hüttinger Elektronik GmbH + Co. KG
• Original Assignee: Hüttinger Elektronik GmbH + Co. KG
• Inventors: Hintz, Gerd, Kirchmeier, Thomas
• Granted Patent: US 8,643,279 B2
• Time in Patent Office: Days
• US Class Current: 156/345.260
• CPC Class Codes: G01R 21/06 by measuring current and voltage G01R21/08 - G01R21/133 take precedence
• CPC Class Codes: G01R 23/02 Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
• CPC Class Codes: H01J 37/32045 Circuits specially adapted for controlling the glow discharge
• CPC Class Codes: H02M 7/003 Constructional details, e.g. physical layout, assembly, wiring or busbar connections
• CPC Class Codes: H02M 7/5383 in a self-oscillating arrangement H02M7/538 takes precedence
• CPC Class Codes: H03H 7/40 Automatic matching of load impedance to source impedance
• CPC Class Codes: H05B 41/2806 with semiconductor devices and specially adapted for lamps without electrodes in the vessel, e.g. surface discharge lamps, electrodeless discharge lamps
• CPC Class Codes: H05H 1/46 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/26 takes precedence
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

Determining a high frequency operating parameter in a plasma system including a plasma power supply device coupled to a plasma load using a hybrid coupler having four ports is accomplished by: generating two high frequency source signals of identical frequency, the signals phase shifted by 90° with respect to one another; generating a high frequency output signal by combining the high frequency source signals in the hybrid coupler; transmitting the high frequency output signal to the plasma load; detecting two or more signals, each signal corresponding to a respective port of the hybrid coupler and related to an amplitude of a high frequency signal present at the respective port; and based on an evaluation of the two or more signals, determining the high frequency operating parameter.

Claims

1. A method of determining high frequency operating parameters in a plasma system including a plasma power supply device coupled to a plasma load using a hybrid coupler having four ports, the method comprising:

generating two high frequency source signals of identical frequency, the signals phase shifted by 90°

with respect to one another;

generating a high frequency output signal by combining the high frequency source signals in the hybrid coupler;

transmitting the high frequency output signal to the plasma load;

detecting two or more signals, each signal corresponding to a respective port of the hybrid coupler and related to an amplitude of a high frequency signal present at the respective port; and

based on an evaluation of the two or more signals,

determining one or more high frequency operating parameters, wherein the high frequency operating parameters are selected from the group consisting of;

a reflection factor of the plasma load,

a voltage standing wave ratio,

a phase angle between a wave running to the plasma load and a wave reflected by the plasma load,

a power of the high frequency signal reflected by the plasma load,

a sum of a power of the high frequency output signal and the power of the high frequency signal reflected by the plasma load, and

a sum of powers reflected by the high frequency signal generators.

2. The method of claim 1, wherein the two or more signals are measured at their respective ports and are detected by subsequent rectification.

3. The method of claim 1, wherein detecting two or more signals comprises detecting a signal at a port through which the high frequency output signal is transmitted to the plasma load.

4. The method of claim 1, wherein detecting the two or more signals comprises digitizing the signals and wherein determining the one or more high frequency operating parameters is effected digitally.

5. The method of claim 1, wherein determining the one or more high frequency operating parameters includes accessing, by a processing device, a table storing values based on the two or more signals.

6. The method of claim 1, wherein detecting the two or more signals includes detecting three signals, each at a respective port of the hybrid coupler.

7. The method of claim 1, further comprising determining the power of the high frequency output signal.

8. The method of claim 1, wherein generating the high frequency output signal comprises controlling or regulating the power of the high frequency output signal as a function of the determined one or more high frequency operating parameters.

9. The method of claim 1, wherein transmitting the high frequency output signal to the plasma load includes controlling an impedance matching of the plasma supply device to the plasma load as a function of the one or more determined high frequency operating parameters.

10. The method of claim 1, wherein determining the one or more high frequency operating parameters comprises determining two or more high frequency operating parameters.

11. A plasma power evaluation device comprising:

a measurement circuit configured to be coupled to a port of a hybrid coupler in a plasma system having two high frequency power sources coupled to a plasma load through the hybrid coupler;

a detector coupled to the measurement circuit and configured to generate a signal corresponding to an amplitude of a high frequency signal received by the detector; and

a processing device coupled to the detector to receive the signal and operable to determine one or more high frequency operating parameters based on the signal;

wherein the one or more high frequency operating parameters are selected from the group consisting of;

a reflection factor of the plasma load,

a voltage standing wave ratio,

a phase angle between a wave running to the plasma load and a wave reflected by the plasma load,

a power of a high frequency signal reflected by the plasma load,

a sum of a power of the high frequency output signal and the power of the high frequency signal reflected by the plasma load, and

a sum of powers reflected by the high frequency power sources.

12. The device of claim 11, wherein the processing device is operable to determine at least two high frequency operating parameters from signals received from two or more detectors.

13. The device of claim 11, further comprising:

an A/D converter coupled between the detector and the processing device to convert the signal from an analog signal to a digital signal;

wherein the processing device comprises a digital signal processor configured to receive and process the digital signal.

14. The device of claim 11, wherein the processing device includes a control output to transmit control signals to the two high frequency power sources.

15. The device of claim 11, wherein the processing device includes a control output to transmit control signals to an impedance matching circuit coupled between the hybrid coupler and the plasma load.

16. A plasma processing power control system for a plasma power system having two high frequency power sources coupled to a hybrid coupler to generate a high frequency output signal for a plasma load, the system comprising:

a set of detection circuits configured to be coupled to respective ports of the hybrid coupler and to generate respective signals corresponding to an amplitude of a high frequency signal detected at the respective port of the hybrid coupler; and

a processing device coupled to the detection circuits to receive the signals and operable to determine a parameter value based on the signals, the parameter value representing a power transfer characteristic associated with power being transferred between the high frequency power sources and the plasma load.

17. The system of claim 16, wherein the processing device is further operable to control the high frequency power sources based on the determined parameter value so as to maintain a constant high frequency output signal.

18. The system of claim 16, wherein the processing device is further operable to control an impedance matching circuit based on the determined parameter value to match an impedance of the plasma load to an output impedance of the plasma power system.

19. The system of claim 16, wherein the power transfer characteristic is a forward power, a reverse power, or a phase angle characteristic.

20. The system of claim 16, wherein each detection circuit of the set of detection circuits includes a respective measurement circuit to couple the detection circuit to the respective port.