Low temperature, high quality silicon dioxide thin films deposited using tetramethylsilane (TMS) for stress control and coverage applications

• US 6,531,193 B2
• Filed: 12/11/2000
• Issued: 03/11/2003
• Est. Priority Date: 07/07/1997
• Status: Expired due to Term

• Current Assignee: Penn State Research Foundation (Pennsylvania State University)
• Original Assignee: Penn State Research Foundation (Pennsylvania State University)
• Inventors: Fonash, Stephen J., Lin, Xin, Reber, Douglas M.
• Primary Examiner(s): MEEKS, TIMOTHY HOWARD
• Application Number:
  US09/734,232
• Publication Number:
  US 20020094388A1
• Time in Patent Office: 820 Days
• Field of Search: 427/563, 427/579, 427/162, 427/167, 427/255.37
• US Class Current: 427/579
• CPC Class Codes: C23C 16/402 Silicon dioxide
• CPC Class Codes: C23C 16/5096 Flat-bed apparatus
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• 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 21/02337 treatment by exposure to a gas or vapour
• CPC Class Codes: H01L 21/31612 on a silicon body

Abstract

Silicon dioxide thin film have been deposited at temperatures from 25° C. to 250° C. by plasma enhanced chemical vapor deposition (PECVD) using tetramethylsilane (TMS) as the silicon containing precursor. At these temperatures, the PETMS oxide films have been found to exhibit adjustable stress and adjustable conformality. Post deposition annealing in forming gas at or below the deposition temperatures has been shown to be very effective in improving the PETMS oxide properties while preserving the low temperature aspect of the PETMS oxides.

Claims

1. A method for forming a silicon dioxide film on a substrate comprising the steps of:

(a) heating said substrate to a deposition temperature of between about 25°

C. to 250°

C.;

(b) providing tetramethylsilane (TMS) in a gas flow amount up to about 1,000 sccm, and an oxygen containing gas in a plasma discharge;

(c) developing pressure between about 0.001 Torr and 100 Torr; and

(d) depositing SiO₂ on said substrate.

2. The method as recited in claim 1, wherein said substrate comprises at least one of:

a semiconductor, a dielectric, a conductor, a glass, a polymer, a plastic, a metal foil or combinations thereof.

3. The method as recited in claim 1, wherein said deposition temperature is from about 100°

C. to 200°

C. and said pressure of step (c) is between about 2 Torr to about 8 Torr.

4. The method as recited in claim 1, wherein said TMS is provided in a gas flow amount up to about 100 sccm in said plasma discharge.

5. The method as recited in claim 1, wherein said plasma discharge comprises oxygen atoms, radicals and ions.

6. The method as recited in claim 1, wherein said TMS to oxygen flow rate ratio is between about 1:

10 to about 1;

2000.

7. The method as recited in claim 1, further comprising the step of providing RF power of between about 1 W to 1000 W.

8. The method as recited in claim 1, further comprising a post-deposition annealing step which comprises applying a forming gas and heating said silicon dioxide film to an annealing temperature at or below said deposition temperature of step (a).

9. The method as recited in claim 8, wherein said forming gas comprises hydrogen and a gas selected from the group consisting of:

argon, nitrogen, helium and mixtures thereof.

10. The method as recited in claim 8, wherein the leakage current through said silicon dioxide film is reduced while said annealing temperature of said silicon dioxide film is maintained at or below said deposition temperature of step (a).

11. The method as recited in claim 8, wherein the interface trap state density of said silicon dioxide film is reduced while said annealing temperature of said silicon dioxide film is maintained at or below said deposition temperature of step (a).

12. The method as recited in claim 8, wherein the oxide charge density in said silicon oxide film is reduced while said annealing temperature of said silicon dioxide film is maintained at or below said deposition temperature of step (a).

13. The method as recited in claim 8, wherein the amount of trapped charges in said dioxide film as demonstrated by bi-directional dynamic capacitance-voltage (C-V) sweep is reduced while said annealing temperature of said silicon dioxide film is maintained at or below said deposition temperature of step (a).

14. The method as recited in claim 1, further comprising the step of providing RF power from about 1 W to about 1000 W.

15. The method as recited in claim 14 wherein the conformality of said silicon dioxide film is adjusted during deposition by varying at least one condition selected from the group consisting of:

TMS flow rate, TMS;

O₂ flow rate ratio, RF power, temperature, substrates material and film thickness.

16. The method as recited in claim 15, wherein said silicon dioxide film exhibits bumps, voids or combinations thereof.

17. The method as recited in claim 1, further comprising at least one step effected during deposition of said silicon dioxide from the group consisting of:

decreasing the deposition temperature of step (a) to less than about 200°

C. but not below about 25°

C. and increasing the pressure of step (c) to above about 3 Torr but not greater than abut 100 Torr wherein said silicon dioxide film exhibits conformal deposition topology on said substrate.

18. The method as recited in claim 17, wherein said deposition temperature is between about 25°

C. to 200°

C. and said pressure is between about 5 Torr and 100 Torr.

19. The method as recited in claim 1, further comprising at least one step from the group consisting of:

increasing the deposition temperature of step (a) to at least about 50°

C. but not above about 250°

C. and decreasing the pressure of step (c) to below about 10 Torr but not below about 0.001 Torr wherein said silicon dioxide film exhibits non-conformal deposition topology having a void or a seam disposed between said film and substrate or within said film.

20. The method as recited in claim 19, wherein said deposition temperature is between about 50°

C. to about 250°

C. and said pressure is below about 8 Torr.

21. A method for controlling during deposition the stress level of a silicon dioxide film which is formed on a substrates comprising the steps of:

(a) heating said substrate to a deposition temperature of between about 25°

C. to 250°

C.;

(b) providing TMS in a gas flow amount up to about 1,000 sccm, and an oxygen containing gas in a plasma discharge;

(c) developing a pressure between about 0.001 Torr and 100 Torr; and

(d) depositing SiO₂ on said substrate, wherein said silicon dioxide film exhibits a stress level between about −

1.0 GPa to 0.5 GPa.

22. The method as recited in claim 21, wherein said silicon dioxide film exhibits a stress level between about −

0.5 GPa to 12 GPa.

23. The method as recited in claim 21, further comprising at least one step during deposition of said silicon dioxide from the group consisting of:

decreasing the deposition temperature of step (a) to not less than about 25°

C. and increasing the pressure of step (c) to not more than about 100 Torr wherein said silicon dioxide film exhibits tensile stress between about 0 GPa to about 0.5 GPa.

24. The method as recited in claim 21, further comprising at least one step during deposition of said silicon dioxide from the group consisting of:

increasing the deposition temperature of step (a) to not more than about 250°

C. and decreasing the pressure of step (c) to not less than about 0.001 Torr wherein said silicon dioxide film exhibits compressive stress between about −

1.0 GPa to about 0 GPa.

25. The method as recited in claim 21, further comprising the providing of RF power from about 1 W to about 1000 W.

26. The method as recited in claim 25 wherein the stress of said silicon dioxide film is adjusted during deposition by varying at least one condition selected from the group consisting of:

TMS flow rate, TMS;

0₂ flow rate ratio, RF power, temperature, deposition pressure, substrate material and film thickness.

27. The method as recited in claim 26, wherein said silicon dioxide film exhibits zero stress of 0 GPa.