Method and apparatus for tuning an RF matching network in a plasma enhanced semiconductor wafer processing system

• US 6,818,562 B2
• Filed: 05/14/2002
• Issued: 11/16/2004
• Est. Priority Date: 04/19/2002
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Gani, Nicolas, Todorow, Valentin, Holland, John
• Primary Examiner(s): HASSANZADEH, PARVIZ
• Application Number:
  US10/146,394
• Publication Number:
  US 20030196757A1
• Time in Patent Office: 917 Days
• Field of Search: 438/9, 438/10, 438/710, 427/8, 427/569, 156/345.24, 156/345.28, 156/345.48, 156/345.47, 118/723.I, 118/723.E, 118/712
• US Class Current: 438/710
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/32183 Matching circuits
• CPC Class Codes: H03H 7/40 Automatic matching of load impedance to source impedance

Abstract

A method and apparatus for operating a matching network within a plasma enhanced semiconductor wafer processing system that uses pulsed power to facilitate plasma processing.

Claims

1. A method of operating a matching network comprising:

applying continuous wave RF power to an antenna assembly to ignite a plasma;

applying continuous wave RF power to a substrate support member;

tuning a matching network in electrical communication with the substrate support member to achieve an impedance match between the continuous wave RF power applied to the substrate support member and a load;

holding the impedance match constant while applying pulsed RF power to at least one of the antenna assembly and the substrate support member.

2. The method of claim 1 wherein the impedance match is tuned by applying a control signal to adjust at least one impedance value of the matching network.

3. The method of claim 2 wherein the at least one impedance value is a capacitance.

4. The method of claim 1 wherein the applying continuous₁₃ wave RF power to a substrate support member has a duration of about 5 seconds.

5. The method of claim 1 further comprising:

measuring a match effectiveness indicator to identify when a substantial impedance match is achieved.

6. The method of claim 5 wherein the match effectiveness indicator is a signal representing reflected power from the matching network.

7. The method of claim 1 wherein the load is a plasma in a plasma reactor.

8. The method of claim 7 wherein the load further comprises the antenna assembly.

9. The method of claim 7 wherein the load further comprises the cathode pedestal.

10. A method of operating a matching network comprising:

applying a first RF power to an antenna assembly to ignite a plasma;

applying a second RF power to a matching network, where the matching network is coupled to a cathode pedestal within a plasma enhanced plasma reactor, the second RF power is applied in a CW mode;

tuning matching parameters of the matching network during the CW mode;

upon achieving a desired impedance match using the matching network, holding the matching parameters constant; and

applying the second RF power in a pulsed mode.

11. The method of claim 10 wherein the plasma enhanced reactor is an etch reactor.

12. The method of claim 10 wherein the CW mode lasts for 5 seconds.