Methods to avoid unstable plasma states during a process transition

• US 8,048,806 B2
• Filed: 03/10/2006
• Issued: 11/01/2011
• Est. Priority Date: 03/17/2000
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Sinha, Ashok, Zhao, Xiaoye, Ma, Shawming, Hoffman, Daniel J., Burns, Douglas H., Kutney, Michael C., Gold, Ezra R., Delgadino, Gerardo A.
• Primary Examiner(s): OLSEN, ALLAN W
• Application Number:
  US11/372,752
• Publication Number:
  US 20070066064A1
• Time in Patent Office: 2,062 Days
• Field of Search: None
• US Class Current: 438/689
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/67069 for drying etching
• CPC Class Codes: H01L 21/76807 for dual damascene structures

Abstract

In some implementations, a method is provided in a plasma processing chamber for stabilizing etch-rate distributions during a process transition from one process step to another process step. The method includes performing a pre-transition compensation of at least one other process parameter so as to avoid unstable plasma states by inhibiting formation of a parasitic plasma during the process transition. In some implementations, a method is provided for processing a workpiece in plasma processing chamber, which includes inhibiting deviations from an expected etch-rate distribution by avoiding unstable plasma states during a process transition from one process step to another process step.

Claims

1. A method of etching in a plasma processing chamber comprising:

conducting a process transition from one process step to another process step, wherein the process transition comprises changing of at least one process parameter; and

performing a pre-transition compensation of at least one other process parameter so as to avoid unstable plasma states by inhibiting formation of a parasitic plasma during the process transition.

2. The method of claim 1 wherein performing the pre-transition compensation comprises increasing a sheath size above a workpiece being processed by initiating application of a bias power prior to the process transition.

3. The method of claim 1 wherein performing a pre-transition compensation comprises increasing a chamber pressure prior to the process transition.

4. The method of claim 3 further comprising reducing the chamber pressure for processing after the process transition.

5. The method of claim 3 wherein performing the pre-transition compensation comprises increasing a chamber pressure prior to the process transition if a source power-to-bias power ratio is greater than about 1.

6. The method of claim 3 wherein performing the pre-transition compensation comprises setting a source power-to-bias power ratio within a range below about 1 for the transition.

7. The method of claim 3 wherein performing the pre-transition compensation comprises initiating a bias power prior to the process transition.

8. The method of claim 7 wherein initiating the bias power comprises setting bias power to about 100 W prior to the process transition.

9. The method of claim 1 wherein performing the pre-transition compensation comprises changing a gas chemistry in the chamber to a non-reactive gas prior to the process transition.

10. The method of claim 9 further introducing a reactive gas after the process transition for processing a workpiece.

11. The method of claim 9 wherein performing the pre-transition compensation comprises changing a gas chemistry in the chamber to a non-reactive gas prior to the process transition if a source power-to-bias power ratio is greater than about 1.

12. The method of claim 9 wherein introducing the non-reactive gas into the plasma processing chamber prior to the process transition comprises starting a flow of the non-reactive gas to the process chamber before the process transition at a time prior to the process transition greater than a residence time of the non-reactive gas to arrive from a gas panel to the processing chamber.

13. The method of claim 12 wherein introducing the non-reactive gas into the plasma processing chamber comprises introducing argon at least 2 seconds prior to the process transition.