Uniform and repeatable plasma processing

• US 5,474,648 A
• Filed: 07/29/1994
• Issued: 12/12/1995
• Est. Priority Date: 07/29/1994
• Status: Expired due to Term

• Current Assignee: Bell Semiconductor, LLC (Hilco Inc. (d/b/a Hilco Global))
• Original Assignee: LSI Logic Corporation (Broadcom, Inc.)
• Inventors: Patrick, Roger, Schoenborn, Philippe, Bose, Frank A.
• Primary Examiner(s): POWELL, WILLIAM A
• Application Number:
  US08/283,296
• Time in Patent Office: 501 Days
• Field of Search: 156/345, 156/626.1, 156/627.1, 156/643.1, 156/657.1, 156/662.1, 204/192.33, 204/298.32, 324/126, 324/127, 216/61, 216/67, 216/79
• US Class Current: 438/10
• CPC Class Codes: H01J 2237/332 Coating
• CPC Class Codes: H01J 2237/334 Etching
• 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 37/32174 Circuits specially adapted for controlling the RF discharge
• CPC Class Codes: H01J 37/32183 Matching circuits
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01J 37/32963 End-point detection
• CPC Class Codes: H01J 37/3299 Feedback systems

Abstract

Dynamic control and delivery of radio frequency power in plasma process systems is utilized to enhance the repeatability and uniformity of the process plasma. Power, voltage, current, phase, impedance, harmonic content and direct current bias of the radio frequency energy being delivered to the plasma chamber may be monitored at the plasma chamber and used to control or characterize the plasma load. Dynamic pro-active control of the characteristics of the radio frequency power to the plasma chamber electrode during the formation of the plasma enhances the uniformity of the plasma for more exact and controllable processing of the work pieces.

Claims

1. A plasma processing system, comprising:

a radio frequency power generator having a radio frequency power output;

a plasma chamber having a radio frequency electrode;

a radio frequency parameter sensor having a radio frequency input connected to said radio frequency power generator and a radio frequency output connected to said plasma chamber electrode, said parameter sensor having a signal output representative of the radio frequency power at said plasma chamber electrode; and

a controller connected to said sensor signal output, wherein said controller controls said radio frequency power generator output so that an initial first desired power value is applied to said electrode for a first amount of time and a second desired power value is applied to said electrode for a second amount of time after the first amount of time has elapsed.

2. The plasma processing system of claim 1, further comprising a radio frequency matching network connected between said power generator output and said parameter sensor radio frequency input.

3. The plasma processing system of claim 1, further comprising a radio frequency circulator connected between said power generator output and said parameter sensor radio frequency input.

4. The plasma processing system of claim 3, wherein said radio frequency circulator has first, second and third ports, wherein the first port is connected to said radio frequency power generator output and the second port is connected to said parameter sensor radio frequency input;

and a termination resistor is connected to said circulator third port, said resistor dissipating reflected power and harmonics from the plasma chamber electrode.

5. The plasma processing system of claim 1, further comprising said parameter sensor measuring the power, voltage, current, phase angle and impedance parameters at said plasma chamber electrode.

6. The plasma processing system of claim 5, wherein said controller dynamically controls the power, voltage, current, phase angle and impedance parameters of said plasma chamber electrode.

7. The plasma processing system of claim 1, further comprising said parameter sensor measuring the voltage on said plasma chamber electrode and said controller limiting the maximum voltage on the electrode by controlling said power generator output.

8. The plasma processing system of claim 1, further comprising said parameter sensor measuring the current through said plasma chamber electrode and said controller limiting the maximum current through the electrode by controlling said power generator output.

9. The plasma processing system of claim 1, wherein said controller is a software program controlled computer system.

10. The plasma processing system of claim 1, wherein said controller is selectively programmable to control a desired process power profile depending on the selected process gas and work piece.

11. The plasma processing system of claim 1, wherein said controller controls the ramp time and overshoot of the radio frequency power from said radio frequency power generator output.

12. The plasma processing system of claim 1, further comprising said controller controlling the plasma gas flow.

13. The plasma processing system of claim 1, further comprising said controller controlling the plasma gas pressure.

14. The plasma processing system of claim 1, further comprising a parameter variance detector connected to said parameter sensor, said parameter variance detector detecting variations in an expected plasma process profile.

15. The plasma processing system of claim 14, further comprising a parameter variance alarm connected to said parameter variance detector for alarming on selected variations in an expected plasma process profile.

16. The plasma processing system of claim 14, wherein said parameter variance detector is characterized to detect a gas leak in said plasma chamber.

17. The plasma processing system of claim 14, wherein said parameter variance detector is characterized to detect contamination in said plasma chamber.

18. The plasma processing system of claim 1, wherein said controller controls a plurality of desired power values and associated times.

19. A method for measuring and controlling process parameters in a plasma processing system, said method comprising the steps of:

monitoring a plurality of radio frequency parameters of a plasma chamber electrode with a parameter sensor connected at the electrode;

dynamically controlling a radio frequency power generator so as to maintain desired parameter values at the plasma chamber electrode during a plasma process.

20. The method of claim 19, wherein the step of dynamically controlling the radio frequency power generator comprises the steps of maintaining a first desired power value for a first amount of time and maintaining a second desired power value for a second amount of time after the first amount of time has elapsed.

21. The method of claim 19, further comprising the step of dynamically controlling the voltage at the plasma chamber electrode.

22. The method of claim 19, further comprising the step of dynamically controlling the current at the plasma chamber electrode.

23. The method of claim 19, further comprising the step of dynamically controlling the phase angle at the plasma chamber electrode.

24. The method of claim 21, further comprising the step of controlling the maximum voltage at the plasma chamber electrode.

25. The method of claim 21, further comprising the step of controlling the maximum current at the plasma chamber electrode.

26. The method of claim 19, further comprising the step of detecting at least one process parameter variation from an expected plasma process parameter profile.

27. The method of claim 26, further comprising the step of alarming when the at least one process parameter varies from an expected plasma process parameter profile.

28. The method of claim 19, further comprising the step of detecting a gas leak in a plasma chamber when monitoring the process parameters by detecting a variation from an expected plasma process parameter profile.

29. The method of claim 19, further comprising the step of detecting contamination in a plasma chamber when monitoring the process parameters by detecting a variation from an expected plasma process parameter profile.

30. The method of claim 19, wherein the step of controlling a radio frequency power generator comprises controlling a plurality of desired power values and associated times at the electrode.