Methods for protecting silicon or silicon carbide electrode surfaces from morphological modification during plasma etch processing
Methods for forming a protective polymeric coating on a silicon or silicon-carbide electrode of a plasma processing chamber are provided. The polymeric coating provides protection to the underlying surface of the electrode with respect to exposure to constituents of plasma and gaseous reactants. The methods can be performed during a process of cleaning the chamber, or during a process for etching a semiconductor substrate in the chamber.
1. A method of depositing a protective polymeric coating in a plasma processing chamber, the method comprising:
supplying a gas composition into a plasma processing chamber which contains an electrode of silicon or silicon carbide which has a plasma-exposed surface, the electrode facing a substrate support for supporting a semiconductor substrate;
energizing the gas composition into the plasma state; and
forming a protective polymeric coating on at least a portion of the plasma-exposed surface of the electrode, the polymeric coating being capable of providing protection against etching of the surface underlying the protective coating during the subsequent plasma etching of the semiconductor substrate in the chamber.
2. The method of claim 1 , wherein the gas composition comprises at least one gas selected from the group consisting of hydrocarbons, fluorocarbons, hydrofluorocarbons and precursors thereof capable of forming the polymeric coating on the plasma-exposed surface of the electrode.
3. The method of claim 1 , wherein the gas composition comprises at least one gas selected from the group consisting of C 2 H 2 , C 2 H 4 , C 3 H 4 , C 3 H 6 , C 4 F 6 , C 4 F 8 , CH 3 F, CH 2 F 2 and mixtures thereof.
4. The method of claim 3 , wherein the gas composition further comprises at least one gas selected from the group consisting of the rare gases, O 2 , H 2 , N 2 , CO, CO 2 and mixtures thereof.
5. The method of claim 1 , wherein the gas composition consists essentially of CH 3 F, O 2 and a rare gas.
6. The method of claim 1 , wherein the electrode is a showerhead electrode of single crystal silicon, polycrystalline silicon or silicon carbide.
7. The method of claim 1 , wherein the polymeric coating formed on the plasma-exposed surface of the electrode has a sufficient thickness to remain on the plasma-exposed surface during the subsequent plasma etching of the semiconductor substrate in the plasma processing chamber.
8. The method of claim 1 , wherein the gas composition is supplied into the plasma processing chamber at a flow rate of from about 100 sccm to about 500 sccm, and the plasma processing chamber is at a pressure of from about 20 mT to about 1000 mT.
9. The method of claim 1 , wherein the polymeric coating is formed on the plasma-exposed surface of the electrode as part of a multi-step process of plasma cleaning interior surfaces of the plasma processing chamber.
10. The method of claim 1 , wherein the polymeric coating is formed on the plasma-exposed surface of the electrode as part of a method of etching the semiconductor substrate in the plasma processing chamber.
11. The method of claim 1 , wherein the gas composition is energized by capacitively-coupling power into the plasma processing chamber.
12. The method of claim 1 , wherein the electrode is a new electrode, a refurbished electrode, or an electrode previously used in the chamber.
13. The method of claim 1 , wherein the protective polymeric coating is formed on the entire plasma-exposed surface of the electrode.
14. The method of claim 1 , wherein the plasma processing chamber contains at least one additional part that is of silicon or silicon carbide and has a plasma-exposed surface, and the protective polymeric coating is formed on the plasma-exposed surface of the at least one additional part.
15. A method of waferless autocleaning of a plasma processing chamber, comprising:
supplying an oxygen-containing cleaning gas composition into a plasma processing chamber which does not contain a production wafer, the chamber contains an electrode of silicon or silicon carbide which has a plasma-exposed surface, the electrode facing a substrate support for supporting a semiconductor substrate;
energizing the cleaning gas composition into the plasma state and cleaning the interior of the chamber;
subsequently supplying a coating gas composition into the chamber;
energizing the coating gas composition into the plasma state; and
forming a polymeric coating on at least a portion of the plasma-exposed surface of the electrode, the polymeric coating provides protection against etching of the surface underlying the coating during the subsequent plasma etching of a semiconductor substrate in the chamber.
16. The method of claim 15 , wherein the coating gas composition comprises at least one gas selected from the group consisting of hydrocarbons, fluorocarbons, hydrofluorocarbons and precursors thereof capable of forming the polymeric coating on the plasma-exposed surface of the electrode.
17. The method of claim 15 , wherein the coating gas composition comprises at least one gas selected from the group consisting of C 2 H 2 , C 2 H 4 , C 3 H 4 , C 3 H 6 , C 4 F 6 , C 4 F 8 , CH 3 F, CH 2 F 2 and mixtures thereof.
18. The method of claim 17 , wherein the coating gas composition further comprises at least one gas selected from the group consisting of the noble gases, O 2 , H 2 , N 2 , CO, CO 2 and mixtures thereof.
19. The method of claim 15 , wherein the coating gas composition consists essentially of CH 3 F, O 2 and a rare gas.
20. The method of claim 15 , wherein the electrode is a showerhead electrode of single crystal silicon, polycrystalline silicon or silicon carbide.
21. The method of claim 15 , wherein the polymeric coating formed on the plasma-exposed surface of the electrode has a sufficient thickness to remain on the plasma-exposed surface during the subsequent plasma etching of a semiconductor substrate in the plasma processing chamber.
22. The method of claim 15 , wherein the coating gas composition is supplied into the plasma processing chamber at a flow rate of from about 100 sccm to about 500 sccm, and the plasma processing chamber is at a pressure of from about 50 mT to about 1000 mT.
23. The method of claim 15 , wherein the cleaning gas composition and the coating gas composition are energized by capacitively-coupling power into the plasma processing chamber.
24. The method of claim 15 , wherein the electrode is a new electrode, a refurbished electrode, or an electrode previously used in the chamber.
25. The method of claim 15 , wherein the protective polymeric coating is formed on the entire plasma-exposed surface of the electrode.
26. The method of claim 15 , wherein the plasma processing chamber contains at least one additional part that is of silicon or silicon carbide and has a plasma-exposed surface, and the protective polymeric coating is formed on the plasma-exposed surface of the at least one additional part.
27. A method for etching a semiconductor substrate, comprising:
supplying a coating gas composition into a plasma processing chamber, the chamber contains an electrode of silicon or silicon carbide which has a plasma-exposed surface, the electrode facing a substrate support supporting a semiconductor substrate;
energizing the coating gas composition into the plasma state;
forming a polymeric coating on at least a portion of the plasma-exposed surface of the electrode;
subsequently supplying an etching gas composition into the chamber;
energizing the etching gas composition into the plasma state; and
plasma etching the semiconductor substrate;
wherein the polymeric coating remains on the plasma-exposed surface of the electrode during the plasma etching of the semiconductor substrate.
28. The method of claim 27 , wherein the coating gas composition comprises at least one gas selected from the group consisting of hydrocarbons, fluorocarbons, hydrofluorocarbons and precursors thereof capable of forming the polymeric coating on the plasma-exposed surface of the electrode.
29. The method of claim 27 , wherein the coating gas composition comprises at least one gas selected from the group consisting of C 2 H 2 , C 2 H 4 , C 3 H 4 , C 3 H 6 , C 4 F 6 , C 4 F 8 , CH 3 F, CH 2 F 2 and mixtures thereof.
30. The method of claim 29 , wherein the coating gas composition further comprises at least one gas selected from the group consisting of the noble gases, O 2 , H 2 , N 2 , CO, CO 2 and mixtures thereof.
31. The method of claim 27 , wherein the coating gas composition consists essentially of CH 3 F, O 2 and a rare gas.
32. The method of claim 27 , wherein the electrode is a showerhead electrode of single crystal silicon or polycrystalline silicon.
33. The method of claim 27 , wherein the plasma processing chamber is at a pressure of from about 20 mT to about 1000 mT, and the coating gas composition is supplied into the plasma processing chamber at a flow rate of from about 100 sccm to about 500 sccm.
34. The method of claim 27 , wherein the coating gas composition and the etching gas composition are energized by capacitively-coupling power into the plasma processing chamber.
35. The method of claim 27 , wherein the etching comprises etching a low-k dielectric material layer of the semiconductor substrate.
36. The method of claim 27 , wherein the electrode is a new electrode, a refurbished electrode, or an electrode previously used in the chamber.
37. The method of claim 27 , wherein the protective polymeric coating is formed on the entire plasma-exposed surface of the electrode.
38. The method of claim 27 , wherein the plasma processing chamber contains at least one additional part that is of silicon or silicon carbide and has a plasma-exposed surface, and the protective polymeric coating is formed on the plasma-exposed surface of the at least one additional part.