METHOD OF PLASMA TREATMENT USING AMPLITUDE-MODULATED RF POWER

• US 20090136683A1
• Filed: 11/27/2007
• Published: 05/28/2009
• Est. Priority Date: 11/27/2007
• Status: Active Grant

• Current Assignee: ASM Japan K.K. (ASM International NV)
• Original Assignee: ASM Japan K.K. (ASM International NV)
• Inventors: Suzuki, Yasuaki, Fukasawa, Yasushi, Shuto, Mitsutoshi
• Granted Patent: US 8,021,723 B2
• Time in Patent Office: Days
• US Class Current: 427/569
• CPC Class Codes: C23C 16/505 using radio frequency discharges
• CPC Class Codes: H01J 37/32091 the radio frequency energy being capacitively coupled to the plasma
• CPC Class Codes: H01J 37/32146 Amplitude modulation, includes pulsing

Abstract

A method for processing a substrate by plasma CVD includes: (i) forming a film on a substrate placed on a susceptor by applying RF power between the susceptor and a shower plate in the presence of a film-forming gas in a reactor; and (ii) upon completion of step (i), without unloading the substrate, applying amplitude-modulated RF power between the susceptor and the shower plate in the absence of a film-forming gas but in the presence of a non-film-forming gas to reduce a floating potential of the substrate.

Claims

1. A method for processing a substrate by plasma CVD, comprising:

(i) forming a film on a substrate placed on a susceptor by applying RF power between the susceptor and a shower plate in the presence of a film-forming gas in a reactor; and

(ii) upon completion of step (i), without unloading the substrate, applying amplitude-modulated RF power between the susceptor and the shower plate in the absence of a film-forming gas but in the presence of a non-film-forming gas to reduce a floating potential of the substrate.

2. The method according to claim 1, wherein the amplitude-modulated RF power used in step (ii) is constant and has an electric power equal to or lower than the electric power of the RF power used in step (i).

3. The method according to claim 2, wherein the amplitude-modulated RF power used in step (ii) has an electric power of 5 W to 50 W.

4. The method according to claim 1, wherein the amplitude-modulated RF power used in step (ii) is ramped down continuously.

5. The method according to claim 1, wherein the amplitude-modulated RF power used in step (ii) is amplitude-modulated with a sine wave of 100 Hz to 500 kHz and has an amplitude modulation ratio of 0.25 to 1.2.

6. The method according to claim 1, wherein the amplitude-modulated RF power used in step (ii) is amplitude-modulated with a sine wave of 1 kHz to 10 kHz and has an amplitude modulation ratio of 0.8 to 1.0.

7. The method according to claim 1, wherein the non-film-forming gas is N₂, N₂O, O₂, Ar, or He.

8. The method according to claim 1, wherein step (ii) is performed for 2 seconds or more but 10 seconds or less.

9. The method according to claim 1, wherein step (ii) is performed for 2 seconds or more but 3 seconds or less.

10. The method according to claim 1, wherein step (ii) is initiated without extinction of a plasma in the reactor.

11. The method according to claim 1, wherein the amplitude-modulated RF power has a frequency of 2 MHz or higher.

12. The method according to claim 1, wherein the film-forming gas in step (i) comprises a source gas and an additive/carrier gas, and the non-film-forming gas in step (ii) comprises the additive/carrier gas without the source gas.

13. The method according to claim 1, further comprising unloading the substrate upon completion of step (ii).

14. The method according to claim 1, wherein step (ii) is initiated immediately before unloading the substrate.

22. The method according to claim 14, wherein the amplitude-modulated RF power is applied to the shower plate.

15. A method for reducing a floating potential of a substrate on a susceptor in a plasma CVD reactor, comprising:

upon completion of processing the substrate in the reactor and before unloading the substrate, applying amplitude-modulated RF power between the susceptor and a shower plate in the absence of a film-forming gas but in the presence of a non-film-forming gas for reducing a floating potential of the substrate to a set level.

16. The method according to claim 15, wherein the amplitude-modulated RF power has an amplitude modulation ratio of 0.25 to 1.2.

17. The method according to claim 15, wherein the amplitude-modulated RF power is amplitude-modulated with a sine wave of less than 500 kHz.

18. The method according to claim 15, wherein the amplitude-modulated RF power is generated by amplitude-modulating RF power which is reduced with time toward the end of the step of applying the amplitude-modulated RF power.

19. The method according to claim 15, wherein the non-film-forming gas is O₂, N₂, or N₂O.

20. The method according to claim 15, wherein the non-film-forming gas comprises an additive/carrier gas without a source gas used in the film formation.

21. The method according to claim 15, wherein the applying of the amplitude-modulated RF power is conducted to reduce a floating potential of the substrate to 1/10 or less of a floating potential of the substrate obtained with RF power without the amplitude modulation.