Methods and apparatus for calibration and metrology for an integrated RF generator system

• US 7,122,965 B2
• Filed: 07/23/2004
• Issued: 10/17/2006
• Est. Priority Date: 02/24/2003
• Status: Expired due to Fees

• Current Assignee: MKS Instruments Incorporated
• Original Assignee: MKS Instruments Incorporated
• Inventors: Goodman, Daniel
• Primary Examiner(s): VU, DAVID HUNG
• Application Number:
  US10/897,580
• Publication Number:
  US 20050057165A1
• Time in Patent Office: 816 Days
• Field of Search: None
• US Class Current: 315/111.21
• 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 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge

Abstract

The invention features RF plasma generation systems, methods for operating the systems, methods for calibrating the systems, and calibration apparatus. One RF plasma generation system includes an impedance matching network having an input port to receive an RF signal from an RF generator, and an output port to deliver the RF signal to an input port of a plasma vessel associated with a load. The system includes an RF signal probe in electromagnetic communication with the input port of the impedance matching network to detect at least one RF signal parameter associated with the RF signal at the input port of the impedance matching network. The system can include a calibration storage unit that stores calibration data. The calibration data includes an association of values of the RF signal parameter with values of at least one characteristic of the load.

Claims

1. A method for operating an RF plasma generation system, the method comprising the steps of:

applying an RF signal to an input port of an impedance matching network having a fixed impedance during operation of the system;

monitoring at least one parameter of the RF signal associated with the input port of the impedance matching network;

providing an output of the impedance matching network to a plasma load;

providing calibration data that associates values of the at least one RF signal parameter with values of at least one characteristic of the load; and

determining a value of the at least one characteristic of the load associated with the monitored value of the at least one parameter of the RF signal by referencing the calibration data.

2. The method of claim 1 comprising providing control information to control operation of the RF plasma generation system.

3. The method of claim 1 wherein the at least one parameter associated with the RF signal at the input of the impedance matching network is one or more of a voltage, a current, a phase, and a power of the signal.

4. The method of claim 1 comprising providing control signals to an RF generator.

5. The method of claim 1 wherein monitoring at least one parameter of the RF signal associated with the input of the impedance matching network comprises probing the RF signal at a location along a pathway of the RF signal between an RF signal generator and the input of the impedance matching network.

6. The method of claim 1 wherein the calibration data comprise power efficiency data comprising values of a ratio of,

i) a power delivered to the load, to

ii) a power of the RF signal at the input of the impedance matching network.

7. The method of claim 1 wherein the at least one parameter associated with the RF signal is a reflection coefficient of the RF signal.

8. The method of claim 1 comprising changing a power of the RF signal associated with the input of the impedance matching network if the monitored value of the characteristic of the load is different from at least one predetermined load criterion.

9. The method of claim 1 wherein monitoring at least one parameter of the RF signal associated with the input port of the impedance matching network comprises monitoring a present value of the at least one parameter.

10. The method of claim 1 comprising adjusting a frequency of the RF signal in response to determining the value of the at least one characteristic of the load associated with the monitored value of the at least one parameter of the RF signal by referencing the calibration data.

19. The method of claim 1 wherein the impedance matching network has a plurality of fixed impedances associated with a plurality of operating recipes of the RF plasma generation system.

20. The method of claim 1 wherein the impedance matching network can be reconfigured with a different fixed impedance.

21. The method of claim 1 wherein the RF signal is a variable frequency RF signal.

11. An RF plasma generation system comprising:

an impedance matching network having a fixed impedance during operation of the system and having an input, to receive an RF signal from an RF generator, and an output, to deliver the RF signal to an input of a plasma vessel associated with a load;

a signal probe in electromagnetic communication with the input of the impedance matching network to detect at least one parameter associated with the RF signal at the input of the impedance matching network;

a calibration storage unit comprising calibration data that associates,

i) values of the at least one RF signal parameter associated with the input port of the impedance matching network, with,

ii) values of at least one characteristic of the load; and

a control unit to determine an association between the detected at least one RF signal parameter and a monitored value of the at least one characteristic of the load by referencing the calibration data.

12. The system of claim 11 wherein the control unit is implemented by one or more of software, firmware and hardware.

13. The system of claim 11 wherein the calibration storage unit and the control unit are implemented within a single piece of hardware.

14. The system of claim 11 comprising an interface to accept control information.

15. The system of claim 11 wherein the at least one parameter associated with the RF signal at the input of the impedance matching network is one or more of a voltage, a current, a phase, and a power of the signal.

16. The system of claim 11 wherein the control unit is in communication with the RF generator.

17. The system of claim 11 wherein the control unit provides control signals to the RF generator.

22. The system of claim 11 wherein the impedance matching network has a plurality of fixed impedances associated with a plurality of operating recipes of the RF plasma generation system.

23. The system of claim 11 wherein the impedance matching network can be reconfigured with a different fixed impedance.

24. The system of claim 11 wherein the RF generator is a variable frequency RF generator.

18. An RF plasma generation system comprising:

an impedance matching network having a fixed impedance during operation of the system and having an input, to receive an RF signal from an RF generator, and an output, to deliver the RF signal to an input of a plasma vessel associated with a load;

a signal probe in electromagnetic communication with the input of the impedance matching network to detect at least one parameter associated with the RF signal at the input of the impedance matching network;

a calibration storage unit comprising calibration data that associates,

i) values of the at least one RF signal parameter associated with the input port of the impedance matching network, with,

ii) values of at least one characteristic of the load; and

means for determining an association between the detected at least one RF signal parameter and a monitored value of the at least one characteristic of the load by referencing the calibration data.