SYSTEMS AND METHODS FOR MONITORING FAULTS, ANOMALIES, AND OTHER CHARACTERISTICS OF A SWITCHED MODE ION ENERGY DISTRIBUTION SYSTEM

• US 20140062495A1
• Filed: 08/28/2012
• Published: 03/06/2014
• Est. Priority Date: 08/28/2012
• Status: Active Grant

• Current Assignee: AES Global Holdings Pte Ltd. (Advanced Energy Industries, Inc. (China))
• Original Assignee: Advanced Energy Industries Incorporated
• Inventors: Carter, Daniel, Brouk, Victor, Hoffman, Daniel J.
• Granted Patent: US 9,685,297 B2
• Time in Patent Office: Days
• US Class Current: 324/459
• CPC Class Codes: G01N 27/06 of a liquid involving electrolysis G01N27/26
• CPC Class Codes: H01J 37/08 Ion sources; Ion guns
• CPC Class Codes: H01J 37/32944 Arc detection
• CPC Class Codes: H01J 37/3299 Feedback systems

Abstract

Systems, methods and apparatus for regulating ion energies in a plasma chamber and chucking a substrate to a substrate support are disclosed. An exemplary method includes placing a substrate in a plasma chamber, forming a plasma in the plasma chamber, controllably switching power to the substrate so as to apply a periodic voltage function (or a modified periodic voltage function) to the substrate, and modulating, over multiple cycles of the periodic voltage function, the periodic voltage function responsive to a defined distribution of energies of ions at the surface of the substrate so as to effectuate the defined distribution of ion energies on a time-averaged basis.

Claims

1. A system for monitoring of a plasma processing chamber, the system comprising:

a plasma processing chamber configured to contain a plasma;

a substrate support positioned within the plasma processing chamber and disposed to support a substrate,

an ion-energy control portion, the ion-energy control portion provides at least one ion-energy control signal responsive to at least one ion-energy distribution setting that is indicative of a desired ion energy distribution at the surface of the substrate;

a switch-mode power supply coupled to the substrate support and the ion-energy control portion, the switch-mode power supply including one or more switching components configured to apply power to the substrate as a periodic voltage function;

an ion current compensation component coupled to the substrate support, the ion current compensation component adding an ion compensation current to the periodic voltage function to form a modified periodic voltage function; and

a controller coupled to the substrate support, the controller determining an ion current in the plasma processing chamber from the ion compensation current and comparing the ion current to a reference current waveform.

2. The system of claim 1, wherein the controller compares the modified periodic voltage function to a reference voltage waveform.

3. The system of claim 2, wherein the controller identifies operating characteristics of the plasma processing chamber without a probe inside the plasma processing chamber.

4. The system of claim 2, wherein the controller identifies operating characteristics of a plasma source configured to ignite and sustain the plasma without a probe inside the plasma processing chamber.

5. The system of claim 1, wherein the controller is further configured to determine a sheath capacitance based on the ion current.

6. The system of claim 5, wherein the controller is further configured to determine further plasma parameters selected from the group consisting of:

a Debye sheath distance, a plasma density, an effective mass of ions in the plasma, and an ion energy of ions in the plasma.

7. A system for monitoring a plasma processing chamber and associated systems, the system comprising:

an electrical node configured for coupling to a substrate support of the plasma processing chamber and for providing a modified periodic voltage function to the substrate support, wherein the modified periodic voltage function comprises a periodic voltage function modified by an ion compensation current;

a switch mode power supply configured to provide the periodic voltage function to the electrical node;

an ion current compensation component configured to provide the ion compensation current to the electrical node;

a controller configured to sample voltage at the electrical node at two or more times and ascertain an ion current in the plasma processing chamber based on the voltage sampled at the electrical node.

8. The system of claim 7, wherein successive cycles of the modified periodic voltage function are substantially identical.

9. The system of claim 8, wherein the modified periodic voltage function includes pulses and portions between the pulses, and wherein a voltage step, Δ

V, corresponds to an ion energy in the plasma processing chamber, and a slope of the portions between the pulses corresponds to an ion energy distribution function of ions in the plasma.

10. The system of claim 8, wherein the controller is configured to sample at a sampling rate high enough to resolve the pulses and the portions between the pulses.

11. The system of claim 10, wherein the sampling is performed at greater than 400 kHz.

12. The system of claim 9, wherein the controller determines a slope of the portions between the pulses.

13. The system of claim 12, wherein the controller determines a standard deviation of the slope.

14. The system of claim 9, wherein the controller determines the voltage step, Δ

V, for each cycle of the modified periodic voltage function.

15. A method for monitoring a plasma processing chamber and associated systems, the method comprising:

providing a modified periodic voltage function to a substrate support of the plasma processing chamber;

sampling at least a portion of the modified periodic voltage function to generate voltage data;

comparing the voltage data to at least a portion of a reference waveform; and

based on the comparing, identifying at least one difference between the voltage data and the at least a portion of the reference waveform to characterize operation of the plasma processing chamber and associated systems.

16. The method of claim 15, further comprising:

sampling at least a portion of the modified periodic voltage function to generate current data;

comparing the current data to at least a portion of the reference waveform; and

based on the comparing, identifying at least one difference between the at least a portion of the modified periodic voltage function and the at least a portion of the reference waveform as characterizing operation of the plasma processing chamber, a plasma source, or a plasma bias power supply.

17. The method of claim 15, wherein the comparing includes comparing the modified periodic voltage function at a first period of time to the modified periodic voltage function at a second period of time

18. The method of claim 15, wherein the portion of the reference waveform is a second portion of the reference waveform.

19. The method of claim 15, wherein the portion of the waveform is a fourth portion of the reference waveform.

20. The method of claim 19, wherein the comparing involves a comparison of a slope of the fourth portion between at least two cycles of the modified periodic voltage function.

21. The method of claim 15, wherein the comparing looks at changes in the waveform over time.

22. The method of claim 15, wherein the comparing looks at a standard deviation of the portion of the modified periodic voltage function.

23. The method of claim 22, wherein the comparing looks at a location of the deviation in a given cycle.

24. The method of claim 15, wherein the comparing looks at a voltage step, Δ

V.

25. The method of claim 15, wherein the comparing involves converting sampled voltage as a function of time into a frequency domain.

26. The method of claim 15, wherein the comparing looks at nonlinearities in the modified periodic waveform.

27. The method of claim 15, wherein the comparing includes converting the ion compensation current to an ion current and comparing the ion current over time.

28. The method of claim 27, wherein the comparing looks at variations in the ion current as a function of process parameters.

29. The method of claim 27, wherein the comparing looks at increases in an average of the ion current.

30. The method of claim 15, wherein the associated systems include a source electrode and electrical systems that provide power to ignite and sustain the plasma.

31. The method of claim 15, wherein the reference waveform is taken from the modified periodic voltage function at a previous time period.

32. The method of claim 15, wherein the identifying is performed in order to characterize faults or anomalies in operation of the plasma processing chamber and associated systems.

33. The method of claim 15, wherein the modified periodic voltage function comprises:

a periodic voltage function; and

an ion compensation current.