Method of controlling the switched mode ion energy distribution system

• US 9,767,988 B2
• Filed: 08/28/2012
• Issued: 09/19/2017
• Est. Priority Date: 08/29/2010
• Status: Active Grant

• Current Assignee: Advanced Energy Industries Incorporated
• Original Assignee: Advanced Energy Industries Incorporated
• Inventors: Brouk, Victor, Hoffman, Daniel J., Carter, Daniel
• Primary Examiner(s): BRAYTON, JOHN JOSEPH
• Application Number:
  US13/596,976
• Publication Number:
  US 20120318456A1
• Time in Patent Office: 1,848 Days
• CPC Class Codes: H01J 37/32009 Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources plasma generation in general H05H1/24
• CPC Class Codes: H01J 37/32174 Circuits specially adapted for controlling the RF discharge
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• 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 comprising:

a power supply configured to provide a periodic voltage function to an output configured to couple to a substrate support, the periodic voltage function having pulses and a portion between the pulses;

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

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

accessing a memory to obtain an effective internal capacitance, C₁, of a plasma processing chamber;

determining the slope, dV₀/dt, of the portion between pulses; and

adjusting a magnitude of the compensation current, I_C, applied to the substrate support until

2. The system of claim 1, wherein the instructions further include identifying an amplitude of the pulses of the periodic voltage function that, when provided to the substrate support, result in a defined ion energy of ions reaching a surface of a substrate on the substrate support.

3. The system of claim 2, wherein the instructions further include adjusting an amplitude of the pulses of the periodic voltage function until the defined ion energy of ions reaching the surface of the substrate is achieved.

9. The system of claim 1, wherein the instructions further comprise:

once

11. The system of claim 1, wherein the instructions further comprise:

calculating a sheath voltage across a plasma sheath of the plasma.

13. The system of claim 1, wherein the effective internal 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.

15. The system of claim 1, wherein the effective internal capacitance value, C₁, also accounts for a capacitance of a substrate coupled to the substrate support.

17. The system of claim 15, wherein the effective internal capacitance value, C₁, also accounts for insulation coupled to the substrate support.

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

4. A system comprising:

an electrical node configured to electrically couple to a substrate support of a plasma processing chamber;

means for storing an effective internal capacitance value, C₁, of the substrate support;

means for providing compensation current, I_C, to the electrical node;

means for providing a periodic voltage function to the electrical node, the periodic voltage function being modified by the compensation current, I_C, to form a modified periodic voltage function at the electrical node, the modified periodic voltage function having pulses and a portion between the pulses;

a controller in communication with the means for providing the compensation current, I_C, and the means for providing the periodic voltage function, the controller encoded with instructions for;

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

adjusting a magnitude of the compensation current, I_C, applied to the substrate support until

5. The system of claim 4, wherein the determining includes sampling a voltage of the portion between the pulses of the modified periodic voltage function at two or more times.

6. The system of claim 5, wherein the determining includes calculating the slope, dV₀/dt, from the voltage sampled at the two or more times.

7. The system of claim 6, wherein the determining includes calculating the slope, dV₀/dt, for two or more cycles of the modified periodic voltage function, where each of the two or more cycles is associated with a different value of the compensation current, I_C.

8. The system of claim 5, wherein the determining includes:

sampling a voltage of the portion between the pulses of the modified periodic voltage function during a first cycle and during a second cycle; and

calculating the slope, dV0/dt, from at least these two sampled voltages.

10. The system of claim 4, wherein the instructions further comprise:

once

12. The system of claim 4, wherein the instructions further comprise:

calculating a sheath voltage across a plasma sheath of the plasma.

14. The system of claim 4, wherein the effective internal 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.

16. The system of claim 4, wherein the effective internal capacitance value, C₁, also accounts for a capacitance of a substrate coupled to the substrate support.

18. The system of claim 16, wherein the effective internal capacitance value, C₁, also accounts for insulation coupled to the substrate support.

20. The system of claim 4, wherein the power supply is configured to be DC-coupled to the plasma processing chamber.