Method of controlling the film properties of PECVD-deposited thin films

• US 7,785,672 B2
• Filed: 12/22/2004
• Issued: 08/31/2010
• Est. Priority Date: 04/20/2004
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Park, Beom Soo, Choi, Soo Young, White, John M., Wang, Qunhua
• Primary Examiner(s): Meeks; Timothy
• Assistant Examiner(s): Gambetta; Kelly M
• Application Number:
  US11/021,416
• Publication Number:
  US 20050255257A1
• Time in Patent Office: 2,078 Days
• Field of Search: None
• US Class Current: 427/569
• CPC Class Codes: C23C 16/345 Silicon nitride
• CPC Class Codes: C23C 16/45565 Shower nozzles
• CPC Class Codes: C23C 16/5096 Flat-bed apparatus
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/3244 Gas supply means
• 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 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/31612 on a silicon body

Abstract

We have discovered methods of controlling a combination of PECVD deposition process parameters during deposition of thin films which provides improved control over surface standing wave effects which affect deposited film thickness uniformity and physical property uniformity. By minimizing surface standing wave effects, the uniformity of film properties across a substrate surface onto which the films have been deposited is improved. In addition, we have developed a gas diffusion plate design which assists in the control of plasma density to be symmetrical or asymmetrical over a substrate surface during film deposition, which also provides improved control over uniformity of deposited film thickness.

Claims

1. A method of improving film deposition uniformity of a PECVD deposited silicon nitride-comprising passivation dielectric film and obtaining a breakdown voltage of about 5 MV/cm or higher over a substrate surface having an equivalent radius of about 0.5 meter or greater, the method comprising:

providing a substrate surface having an equivalent radius of about 0.5 meter or greater within a PECVD processing chamber;

supplying a plasma source gas comprising NH₃, SiH₄, N₂, and H₂, where the ratio of NH₃;

SiH₄ ranges from about 5.6 to about 11.1, where the ratio of N₂;

SiH₄ ranges from about 5.8 to about 20.8, and wherein an amount of H₂ added to the plasma source gas is controlled so that the amount of H₂ does not exceed 30 volume % of the total gas flow to said processing chamber, whereby film uniformity across said substrate surface varies by less than about 10%, and a breakdown voltage of said silicon nitride-comprising passivation dielectric film does not fall below about 5 MV/cm.

2. A method in accordance with claim 1, wherein a plasma sheath thickness, s, between a parallel plate electrode and a plasma region present within said processing chamber is more than about 20 mils.

3. A method in accordance with claim 1, wherein spacing between electrodes within said processing chamber ranges between about 400 mils and 1200 mils.

4. A method in accordance with claim 1, wherein power applied to said PECVD processing chamber to produce said plasma is RF power which is applied at a frequency ranging between about 27.12 MHZ and about 7 MHZ.

5. A method in accordance with claim 1, wherein the total gas flow to said processing chamber is such that the volumetric gas turnover is at least 0.015 process chamber volumes per minute.

6. A method in accordance with claim 5, wherein said volumetric gas turnover ranges from about 0.015 to about 0.08 processing chamber volumes per minute.

7. A method in accordance with claim 6, wherein said volumetric gas turnover ranges from about 0.02 to about 0.07 processing chamber volumes per minute.

8. A method in accordance with claim 1, wherein the temperature of said substrate ranges from about 100°

C. to about 400°

C. during deposition of said silicon nitride-comprising passivation dielectric film.

9. A method in accordance with claim 8, wherein the temperature of said substrate ranges from about 240°

C. to about 340°

C. during deposition of said silicon nitride-comprising passivation dielectric film.

10. A method in accordance with claim 1, wherein a ratio of NH₃ to SiH₄ within said plasma source gas is within a range of about 2:

1 to about 30;

1.

11. A method in accordance with claim 10, wherein a ratio of NH₃ to SiH₄ within said plasma source gas is within a range of about 2:

1 to about 15;

1.

12. A method in accordance with claim 10, wherein RF power is provided to said processing chamber at a power density within the range of about 0.175 W/cm² to about 0.55 W/cm².

13. A method in accordance with claim 1, wherein a ratio of N₂ to SiH₄ within said plasma source gas is within a range of about 5:

1 to about 80;

1.

14. A method in accordance with claim 13, wherein a ratio of N₂ to SiH₄ within said plasma source gas is within a range of about 5:

1 to about 60;

1.

15. A method in accordance with claim 1, wherein a ratio of NH₃ to N₂ within said plasma source gas is within a range of about 1:

10 to about 3;

1.

16. A method in accordance with claim 15, wherein a ratio of NH₃ to N₂ within said plasma source gas is within a range of about 1:

7 to about 2;

1.

17. A method in accordance with claim 1, wherein said H₂ comprises about 15 volume % to about 25 volume % of said plasma source gas.

18. A method in accordance with claim 1, wherein a process chamber pressure during film deposition is within the range of about 0.7 Torr to about 2.5 Torr.

19. A method in accordance with claim 18, wherein said process chamber pressure is within the range of about 0.9 Torr to about 1.8 Torr.

20. A method in accordance with claim 1, wherein RF power is provided to said processing chamber at a power density within the range of about 0.125 W/cm² to about 0.75 W/cm².