Method of improving the uniformity of PECVD-deposited thin films

• US 7,754,294 B2
• Filed: 06/25/2008
• Issued: 07/13/2010
• Est. Priority Date: 04/20/2004
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Choi, Soo Young, Won, Tae Kyung, White, John M.
• Primary Examiner(s): TUROCY, DAVID P
• Application Number:
  US12/215,602
• Publication Number:
  US 20080268176A1
• Time in Patent Office: 748 Days
• Field of Search: 427/569, 427/574
• US Class Current: 427/569
• CPC Class Codes: H01L 21/0214 the material being a silicon oxynitride, e.g. SiON or SiON:H
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• CPC Class Codes: H01L 21/0217 the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz H01L21/02126 and H01L21/0214 take precedence
• CPC Class Codes: H01L 21/02211 the compound being a silane, e.g. disilane, methylsilane or chlorosilane
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/3185 of siliconnitrides

Abstract

We have discovered that controlling a combination of PECVD deposition process parameters during deposition of silicon-containing thin film provides improved control over surface standing wave effects. By minimizing surface standing wave effects, the uniformity of film properties (particularly film thickness) across a substrate surface onto which the films have been deposited is improved.

Claims

1. A method of improving film deposition uniformity of a PECVD deposited film, wherein a deposition plasma is formed directly over a substrate surface having an equivalent radius of about 0.7 meter or greater, comprising:

providing a substrate having a surface equivalent radius of about 0.7 meter or greater;

placing said substrate in a parallel plate processing chamber;

setting an electrode spacing between parallel plate electrodes in said parallel plate processing chamber to be below about 1000 mils;

setting an R.F. power frequency to be between about 13.56 MHZ and about 3 MHZ;

setting an electron density of a plasma used during deposition of said PECVD-deposited film to be less than about 10¹⁰/cm³;

selecting a plasma source gas in which reactive species are dissociated at an electron density used during deposition of said film;

setting a total gas flow in said processing chamber so that a volumetric gas turnover rate in said processing chamber is at least 0.015 processing chamber volumes per minute; and

depositing said PECVD-deposited film, wherein surface standing wave effects are controlled during film deposition, so that a film deposition rate of at least 1,000Å

/min is achieved over said substrate surface having an equivalent radius of about 0.7 meter or greater, in combination with a film thickness variation over said substrate surface of less than about 10.8 %.

2. A method in accordance with claim 1, wherein said PECVD deposited film is a silicon-containing film.

3. A method in accordance with claim 2, wherein said silicon-containing film is selected from the group consisting of silicon nitride, silicon oxide, and combinations thereof.

4. A method in accordance with claim 3, wherein an a-SiN_x:

H film is deposited and wherein the ratio of NH₃;

SiH₄ in the plasma source gas ranges from about 3.4 to about 10.0, while the ratio of NH₂;

NH₃ ranges from about 1.9 to about 2.9, whereby the variation in film thickness uniformity over said substrate surface increases to range from about 8.3 % to about 10.8 % , while a Si—

H bonded content is reduced to less than about 15 atomic %.

5. A method in accordance with claim 1 or claim 2, wherein a pressure at the surface of the substrate during film formation is less than about 1.5 Torr.

6. A method in accordance with claim 5, wherein said pressure ranges from about 0.5 Torr to about 1.5 Torr.

7. A method in accordance with claim 6, wherein said pressure ranges from about 0.7 Torr to about 1.0 Torr.

8. A method in accordance with claim 1 or claim 2, wherein a plasma sheath width, s, is more than about 20 mils.

9. A method in accordance with claim 1 or claim 2, wherein said plasma thickness, 2d, is less than about 1000 mils.

10. A method in accordance with claim 2, wherein an a-SiN_x:

H film is deposited and wherein the concentration of NH₃ in the plasma source gas mixture is such that the ratio of NH₃;

SiH₄ ranges from about 2;

1 to about 15;

1, and the ratio of NH₃;

N₂ ranges from about 0.3;

1 to about 2;

1.

11. A method in accordance with claim 1 or claim 2, wherein said spacing between electrodes ranges between about 400 mils and about 1000 mils.

12. A method in accordance with claim 1 or claim 2, wherein the amount of RF power applied to the plasma source gas ranges from about 0.2 W / cm² of substrate to about 0.6 W / cm² of substrate.

13. A method in accordance with claim 1 or claim 2, wherein the temperature of said substrate ranges from about 200°

C. to about 400°

C. during deposition of said film.

14. A method in accordance with claim 1, wherein said frequency ranges between about 13.56 MHZ and about 7 MHZ.

15. A method in accordance with claim 1, wherein said volumetric gas turnover rate ranges from about 0.015 to about 0.08 chamber volumes per minute.

16. A method in accordance with claim 15, wherein said volumetric gas turnover rate ranges from about 0.02 to about 0.07 chamber volumes per minute.

17. A method in accordance with claim 1, wherein said method is used to deposit a silicon-containing film selected from the group consisting of silicon nitride, silicon oxide, silicon oxynitride, a-Si, doped a-Si, and combinations thereof.