Pulsed bias having high pulse frequency for filling gaps with dielectric material

• US 7,514,375 B1
• Filed: 08/08/2006
• Issued: 04/07/2009
• Est. Priority Date: 08/08/2006
• Status: Active Grant

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Inventors: Lang, Chi-I, Shanker, Sunil
• Primary Examiner(s): EVERHART, CARIDAD
• Application Number:
  US11/500,799
• Time in Patent Office: 973 Days
• Field of Search: 438/788, 438/789, 438/790, 257/E21.274, 257/E21.279, 257/E21.49, 427/255.37
• US Class Current: 438/788
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/0228 deposition by cyclic CVD, e.g. ALD, ALE, pulsed CVD
• CPC Class Codes: H01L 21/31608 Deposition of SiO2 H01L21/31625, H01L21/31629 and H01L21/31633 take precedence
• CPC Class Codes: H01L 21/76837 Filling up the space between adjacent conductive structures; Gap-filling properties of dielectrics

Abstract

During bottom filling of high aspect ratio gaps and trenches in an integrated circuit substrate using HDP-CVD, a pulsed HF bias is applied to the substrate. In some embodiments, pulsed HF bias is applied to the substrate during etching operations. The pulsed bias typically has a pulse frequency in a range of about from 500 Hz to 20 kHz and a duty cycle in a range of about from 0.1 to 0.95.

Claims

1. In integrated circuit fabrication, a method for filling a gap with dielectric material by HDP-CVD, comprising:

providing in a vacuum chamber a substrate containing a gap;

providing a process gas including dielectric-forming constituents;

providing a plasma discharge to create in said vacuum chamber excited species from said process gas;

applying a bias to said substrate, thereby depositing dielectric material in said gap to fill partially said gap and simultaneously sputtering dielectric material in said gap;

wherein said applying a bias comprises;

applying a pulsed bias to said substrate, said pulsed bias having a pulse frequency not less than about 150 Hz, pulses of said pulsed bias having a duty cycle.

2. A method as in claim 1 wherein:

said pulse frequency has a frequency in a range of about from 0.5 kHz to 20 kHz.

3. A method as in claim 1 wherein:

duty cycles have a value in a range of about from 0.1 to 0.9.

4. A method as in claim 1 wherein:

said pulsed bias comprises high-frequency radio frequency (HF-RF) bias.

5. A method as in claim 1 wherein:

said gap has an aspect ratio greater than 3.

6. A method as in claim 1 wherein said providing a plasma discharge comprises:

applying a substantially continuous radio frequency to a plasma-forming gas to generate a plasma.

15. A method as in claim 1 wherein said process gas comprises:

silicon atoms and oxygen atoms.

16. A method as in claim 15 wherein said process gas further comprises:

hydrogen gas.

17. A method as in claim 15 wherein said process gas further comprises a noble gas.

18. A method as in claim 17 wherein said process gas further comprises a chemical etch gas.

19. A method as in claim 1 wherein:

said gap has a gap width in a range of about from 30 nm to 50 nm.

20. A method as in claim 19 wherein:

said gap has a gap depth in a range of about from 300 nm to 450 nm.

7. In integrated circuit fabrication, a method for filling a gap with dielectric material by HDP-CVD, comprising:

providing in a vacuum chamber a substrate containing a gap;

in a deposition stage;

providing a deposition gas including dielectric-forming constituents;

providing a plasma discharge to create in said vacuum chamber excited species from said deposition gas; and

applying a bias to said substrate, thereby depositing dielectric material in said gap to fill partially said gap and simultaneously sputtering dielectric material in said gap; and

thereafter, in an etch stage;

providing an etch gas;

providing a plasma discharge to create excited species in said vacuum chamber from said etch gas, thereby etching a portion of dielectric material in said gap; and

applying a bias to said substrate, thereby sputtering dielectric material in said gap;

wherein said applying a bias in said deposition stage and in said etch stage comprises;

applying a pulsed bias to said substrate, said pulsed bias having a pulse frequency not less than about 150 Hz, pulses of said pulsed bias having a duty cycle.

8. A method as in claim 7 wherein:

said pulse frequency has a frequency in a range of about from 0.5 kHz to 20 kHz.

9. A method as in claim 7 wherein:

duty cycles have a value in a range of about from 0.1 to 0.9.

10. A method as in claim 7 wherein:

said pulsed bias comprises high-frequency radio frequency (HF-RF) bias.

11. A method as in claim 7, further comprising:

repeating a deposition stage preceded by an etch stage until said gap is filled with dielectric material.

12. A method as in claim 7 wherein:

said etch gas does not include components for substantially forming dielectric material.

13. A method as in claim 7 wherein:

said etch gas comprises dielectric-forming constituents.

14. A method as in claim 7 wherein:

said etch gas comprises components substantially for sputtering dielectric material; and

said etch gas does not include a chemical etching species.

21. A method as in claim 7 wherein said deposition gas comprises:

silicon atoms and oxygen atoms.

22. A method as in claim 21 wherein said deposition gas further comprises:

hydrogen gas.

23. A method as in claim 21 wherein said deposition gas further comprises a noble gas.

24. A method as in claim 7 wherein said etch gas comprises:

a chemical etching species; and

components substantially for physically sputtering dielectric material.

25. A method as in claim 24 wherein:

said etch gas comprises a halogen-containing compound.

26. A method as in claim 25 wherein:

said etch gas comprises a fluorine-containing compound.

27. A method as in claim 24 wherein:

said etch gas comprises a noble gas.