Systems and methods for monitoring faults, anomalies, and other characteristics of a switched mode ion energy distribution system

• US 9,685,297 B2
• Filed: 08/28/2012
• Issued: 06/20/2017
• 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: Hoffman, Daniel J., Carter, Daniel, Brouk, Victor
• Primary Examiner(s): BRAYTON, JOHN JOSEPH
• Application Number:
  US13/597,093
• Publication Number:
  US 20140062495A1
• Time in Patent Office: 1,757 Days
• 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 a plasma processing chamber, the system comprising:

a power supply configured to provide a periodic voltage function to an output that is configured to couple to the plasma processing chamber, the periodic voltage function having pulses and a portion between the pulses;

an ion current compensation component configured to provide ion current compensation, I_c, to the output to modify a slope, dV₀/dt, of the portion between the pulses to form a modified periodic voltage function;

a memory to store an effective capacitance value, C₁, of at least a substrate support of the plasma processing chamber; and

a controller in communication with the power supply, the ion current compensation component, a non-transitory tangible computer readable medium, and the memory, wherein the non-transitory tangible computer readable medium is encoded with instructions, and wherein the controller is configured to execute the instructions, the instructions comprising;

determining the slope, dV₀/dt, of the portion between the pulses of the modified periodic voltage function;

adjusting a magnitude of the ion current compensation, I_C, until

4. The system of claim 1, wherein the effective capacitance value, C₁, includes capacitances of an electrical path between the output and the substrate support as well as one or more capacitances of the substrate support.

5. The system of claim 4, wherein the effective capacitance value, C₁, also accounts for a capacitance of the substrate.

6. The system of claim 5, wherein the effective capacitance value, C₁, also accounts for insulation coupled to the substrate support.

7. The system of claim 1, wherein the power supply is configured to be DC-coupled to the plasma processing chamber.

8. The system of claim 1, wherein the controller instructions further include comparing the modified periodic voltage function to a reference waveform, wherein differences between the modified periodic voltage function and the reference waveform are indicative of a fault.

9. The system of claim 1, wherein the controller instructions further include comparing portions of each cycle of the modified periodic voltage function to each other, and if variations between cycles above a threshold are observed, then a fault indication is triggered.

10. The system of claim 1, wherein the controller instructions further include identifying a fourth portion of the modified periodic voltage function, and if this fourth portion has a nonlinear slope, then identifying a nonlinear change in capacitance of the system.

19. The system of claim 1, wherein the tangible computer readable medium and the memory are the same.

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

a power supply configured to provide a periodic voltage function to an output that is configured to couple to the plasma processing chamber, the periodic voltage function having pulses and a portion between the pulses;

an ion current compensation component configured to provide ion current compensation, I_C, to the output to modify a slope of the portion between the pulses to form a modified periodic voltage function, the ion current compensation component including;

a controllable DC current source, controlling for current, that is consistently coupled to the output; and

a current controller encoded to maintain a constant rate of change of a voltage of the portion between the pulses by;

determining a slope, dV₀/dt, of the portion between the pulses of the modified periodic voltage function;

controlling the controllable DC current source to adjust a magnitude of the ion current compensation, I_C, until

11. The system of claim 2, wherein the controllable DC current source comprises at least a power supply in series with an inductive element.

12. The system of claim 2, wherein the controller instructions further include:

altering an amplitude of voltage of the modified periodic voltage function generated by the power supply; and

adjusting the DC current source such that the modified periodic voltage function is altered to a greater extent than if one of the voltage or ion current compensation were altered alone.

13. The system of claim 2, wherein the controller instructions further include comparing the modified periodic voltage function to a reference waveform, wherein differences between the modified periodic voltage function and the reference waveform are indicative of a fault in the system.

14. The system of claim 2, wherein the controller instructions further include comparing portions of each cycle of the modified periodic voltage function to each other, and if variations between cycles above a threshold are observed, then a fault indication is triggered.

15. The system of claim 2, wherein the controller instructions further include identifying a portion of the modified periodic voltage function having a slope dV₀/dt, and if this slope is nonlinear, then recognizing that the system is experiencing a nonlinear change in capacitance.

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

a DC power supply that provides a DC voltage that is fixed at a magnitude responsive to an ion-energy setting, wherein the ion-energy setting is indicative of a monoenergetic distribution of ion energy at the surface of a substrate within the plasma processing chamber;

an output disposed to couple to a substrate support;

two switching components including a first switching component coupled to the DC power supply and a second switching component couple to a ground terminal, the two switching components configured to generate a periodic voltage function at the output by alternately coupling the DC voltage and the ground terminal to the output, the periodic voltage function having pulses and a portion between the pulses; and

an ion current compensation component coupled to the output, the ion current compensation component including;

a controllable DC current source, separate from the DC power supply, that is consistently coupled to the output; and

a current controller configured to monitor a rate of change of a voltage of the portion between the pulses and maintain an uninterrupted ion current compensation current, I_C, which is fixed in magnitude, to maintain a fixed rate of change of the voltage; and

a controller configured to monitor changes of I_c over time to monitor a condition of the processing chamber.

16. The system of claim 3, wherein the controller instructions further include comparing the modified periodic voltage function to a reference waveform, wherein differences between the modified periodic voltage function and the reference waveform are indicative of a fault in the system.

17. The system of claim 3, wherein the controller instructions further include comparing portions of each cycle of the modified periodic voltage function to each other, and if variations between cycles above a threshold are observed, then a fault indication is triggered.

18. The system of claim 3, wherein the controller instructions further include determining slope dV₀/dt, and if this slope is nonlinear, then recognizing that the system is experiencing a nonlinear change in capacitance.