Solid state RF power switching network

• US 6,794,951 B2
• Filed: 08/05/2002
• Issued: 09/21/2004
• Est. Priority Date: 08/05/2002
• Status: Expired due to Fees

• Current Assignee: Veeco Instruments Incorporated
• Original Assignee: Veeco Instruments Incorporated
• Inventors: Finley, Kenneth Wilbert
• Primary Examiner(s): Tokar, Michael
• Assistant Examiner(s): NGUYEN, KHAI M
• Application Number:
  US10/212,967
• Publication Number:
  US 20040021525A1
• Time in Patent Office: 778 Days
• Field of Search: 333/17.3, 333/32-33, 333/262
• US Class Current: 333/32
• CPC Class Codes: H03H 11/28 Impedance matching networks

Abstract

An RF matching network includes a switching element that quickly switching between a first matching sub-network and a second matching sub-network, such that the impedance of neither sub-network is coupled to the other when selected by the switch. In one embodiment, the switching element includes a bipolar transistor, a TRIAC device and a PIN diode. The PIN diode conducts or attenuates the RF signal depending on its bias voltage. The bipolar transistor controls the bias voltage on the PIN diode. The TRIAC device protects the bipolar transistor damage that can be caused from high voltages generated at the PIN diode when the PIN diode is not conducting the RF signal.

Claims

1. A radio frequency matching network having a radio frequency power signal input and a radio frequency power signal output, the radio frequency matching network comprising:

a first matching sub-network having a first load impedance matching impedance in a first mode of powering a plasma load;

a second matching sub-network having a second load impedance matching impedance in a second mode of powering a plasma load; and

at least one switching element positioned to switch between the first matching sub-network and the second matching sub-network, in the first mode, the at least one switching element coupling the radio frequency power signal input and the radio frequency power signal output through the first matching sub-network and isolating the radio frequency power signal input and the radio frequency power signal output from the second matching sub-network, and in the second mode, the at least one switching element coupling the radio frequency power signal input and the radio frequency signal power output through the second matching sub-network and isolating the radio frequency power signal input and the radio frequency power signal output from the first matching sub-network.

2. The radio frequency matching network of claim 1 wherein the at least one switching element comprises:

a diode coupled to receive an input radio frequency power signal and to output an output radio frequency power signal;

a bipolar transistor having a collector terminal electrically coupled to the diode, the bipolar transistor providing a forward bias voltage to the diode in the first mode and a non-forward bias voltage in the second mode, wherein the diode conducts the input radio frequency power signal to its output to provide the output radio frequency power signal in the first mode and does not conduct the input radio frequency power signal to its output to provide the output radio frequency power signal in the second mode.

3. The radio frequency matching network of claim 2 wherein the at least one switching element further comprises:

a TRIAC device coupled between the bipolar transistor and the diode conducting the forward bias voltage from the bipolar transistor when the bipolar transistor is on.

4. The radio frequency matching network of claim 1 wherein the at least one switching element further comprises:

a TRIAC device coupled between the bipolar transistor and the diode isolating the bipolar transistor from the diode when the bipolar transistor is off and the diode is non-conducting.

5. The radio frequency matching network of claim 1 wherein the at least one switching element further comprises:

a first switching element coupled in the first matching network between a control signal input and the radio frequency power signal input; and

a second switching element coupled in the first matching network between a control input signal and the radio frequency power signal output.

6. The radio frequency matching network of claim 5 wherein the at least one switching element further comprises:

a third switching element coupled in the second matching network between a control signal input and the radio frequency power signal input; and

a fourth switching element coupled in the second matching network between a control input signal and the radio frequency power signal output.

7. The radio frequency matching network of claim 1 wherein the first mode and second mode operate separately in time.

8. The radio frequency matching network of claim 1 wherein the first made is a START mode and the second mode is a RUN mode.

9. The radio frequency matching network of claim 1 wherein the RF power signal operates on a single load.

10. The radio frequency matching network of claim 9 wherein the single load includes an antenna in a plasma chamber.

11. The radio frequency matching network of claim 1 wherein the at least one switching element couples the radio frequency power signal input and the radio frequency power signal output through the second matching sub-network in the second mode fast enough to maintain a plasma.

12. The radio frequency matching network of claim 1 further comprising a keeper circuit providing power to a keeper grid, the keeper grid maintaining a charge in a plasma chamber.

13. The radio frequency matching network of claim 12 wherein the keeper circuit further comprises two fixed capacitors and an inductor to isolate the radio frequency power signal input from a DC power supply feeding the keeper circuit.

14. A switching element for conducting an input radio frequency signal to provide an output radio frequency signal, the switching element comprising:

a diode coupled to receive an input radio frequency signal and to output an output radio frequency signal;

a bipolar transistor having a collector terminal electrically coupled to the diode, the bipolar transistor providing a forward bias voltage to the diode in a first mode and a non-forward bias voltage in a second mode, wherein the diode conducts the input radio frequency to its output to provide the output radio frequency signal in the first mode and does not conduct the input radio frequency to its output to provide the output radio frequency signal in the second mode; and

a TRIAC device coupled to the bipolar transistor to isolate the radio frequency signal from the bipolar transistor.

15. The switching element of claim 14 wherein said TRIAC device is coupled between the bipolar transistor and the diode conducting the forward bias voltage from the bipolar transistor when the bipolar transistor is on.

16. The switching element of claim 14 wherein said TRIAC device is coupled between the bipolar transistor and the diode isolating the bipolar transistor from the diode when the bipolar transistor is off and the diode is non-conducting.

17. A method of switching a radio frequency signal, the radio frequency signal being input to a radio frequency input, the method comprising:

coupling a PIN diode between the radio frequency input and a radio frequency output;

coupling a transistor to an input to the PIN diode, the transistor receiving a control signal;

isolating the radio frequency input from the transistor with a TRIAC device;

attenuating the radio frequency signal at the PIN diode when the control signal turns off the transistor; and

conducting the radio frequency signal through the PIN diode to the radio frequency output when the control signal turns on the transistor.

18. The method of claim 17 further comprising:

coupling the TRIAC device between the transistor and the PIN diode.

19. The method of claim 17 further comprising:

coupling a radio frequency matching impedance between the radio frequency signal input and the PIN diode.

20. A method of switching a radio frequency power signal between a first matching sub-network having a first load impedance matching impedance in a first mode of powering a plasma load and a second matching sub-network having a second load impedance matching impedance in a second mode of powering a plasma load, the radio frequency power signal being input to a radio frequency input, the method comprising:

operating in a first mode by;

coupling the radio frequency power signal input and the radio frequency signal output through the first matching sub-network;

isolating the radio frequency power signal input and the radio frequency power signal output from the second matching sub-network; and

operating in a second mode by;

coupling the radio frequency power signal input and the radio frequency power signal output through the second matching sub-network;

isolating the radio frequency power signal input and the radio frequency power signal output from the first matching sub-network.

21. The method of claim 20 wherein the radio frequency power signal input and the radio frequency power signal output is coupled through the first matching sub-network is via a first PIN diode and through the second matching sub-network via a second PIN diode.

22. The method of claim 20 further comprising:

providing a forward bias voltage from a transistor to the first PIN diode to conduct the radio frequency power signal through the first matching sub-network; and

providing a non-forward bias voltage from the transistor to the second PIN diode.

23. The method of claim 22 further comprising isolating the transistor from the second PIN diode by a TRIAC device when the second PIN diode is non-conducting.

24. The method of claim 20 further comprising:

providing a forward bias voltage from a transistor to the second PIN diode to conduct the radio frequency power signal through the second matching sub-network; and

providing a non-forward bias voltage from the transistor to the first PIN diode.

25. The method of claim 24 further comprising isolating the transistor from the first PIN diode by a TRIAC device when the first PIN diode is non-conducting.

26. The method of claim 20 further comprising operating in the first mode separately in time from operating in the second mode.

27. The method of claim 20 further comprising coupling the radio frequency power signal through the first matching sub-network and coupling the radio frequency power signal through the second matching sub-network to a single load.

28. The method of claim 20 wherein switching between operating in the first mode and operating in the second mode is fast enough to maintain a plasma.

29. The method of claim 20 further comprising maintaining a charge in a plasma chamber with a keeper circuit during operation in the first mode and operation in the second mode.

30. The method of claim 20 further comprising isolating the radio frequency power signal input from a DC power supply feeding a keeper circuit providing power to the keeper grid.