Chemically enhanced anneal for removing trench stress resulting in improved bipolar yield

• US 6,271,100 B1
• Filed: 02/24/2000
• Issued: 08/07/2001
• Est. Priority Date: 02/24/2000
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ballantine, Arne Watson, Gilbert, Jeffrey D., Coolbaugh, Douglas Duane
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): HOANG, QUOC DINH
• Application Number:
  US09/512,159
• Time in Patent Office: 530 Days
• Field of Search: 438/424, 438/433, 438/444, 438/449, 438/221, 438/218, 438/296, 257/397, 257/519
• US Class Current: 438/424
• CPC Class Codes: H01L 21/76224 using trench refilling with dielectric materials trench filling with polycristalline silicon H01L21/763; together with vertical isolation, e.g. trench refilling in a SOI substrate H01L21/76264

Abstract

A method of substantially reducing stress in a trench comprising forming at least one trench in a substrate, said substrate having a surface; filling the at least one trench with a trench dielectric material; planarizing the filled trench stopping on said surface of said substrate; and subjecting the planarized trench to an anneal step, said anneal step being carried out under rapid thermal conditions at a temperature of about 800° C. or above and in the presence of an atmosphere comprising hydrogen.

Claims

1. A method of substantially reducing stress in a trench comprising:

(a) forming at least one trench in a substrate, said substrate having a surface;

(b) filling the at least one trench with a trench dielectric material;

(c) planarizing the filled trench stopping on said surface of said substrate; and

(d) subjecting the planarized trench to an anneal step so as to substantially reduce stress at corner regions that exist between the planarized trench and said substrate, said anneal step is carried out under rapid thermal conditions at a temperature of about 800°

C. or above and in the presence of an atmosphere comprising hydrogen.

2. The method of claim 1 wherein said substrate is composed of Si, Ge, SiGe, GaAs, InAs, InP or a layered semiconductor.

3. The method of claim 2 wherein said substrate is composed of Si, SiGe or a layered Si/SiGe substrate.

4. The method of claim 1 wherein step (a) includes forming a film stack on the surface of said substrate, forming a patterned photoresist on said film stack, said pattern exposing regions of said film stack in which said at least one trench is to be formed and etching said at least one trench through said exposed regions of said film stack.

5. The method of claim 4 wherein said film stack comprises an oxide layer and a nitride layer, said oxide layer being formed on said surface of said substrate.

6. The method of claim 5 wherein said oxide layer of said film stack is thermally grown or deposited.

7. The method of claim 6 wherein said oxide layer of said film stack is deposited by chemical vapor deposition (CVD), plasma-assisted CVD, sputtering or evaporation.

8. The method of claim 5 wherein said oxide layer of said film stack has a thickness of from about 2 to about 20 nm.

9. The method of claim 8 wherein said oxide layer of said film stack has a thickness of from about 5 to about 10 nm.

10. The method of claim 5 wherein said nitride layer of said film stack is formed by a deposition process selected from the group consisting of CVD, plasma-assisted CVD, evaporation and sputtering.

11. The method of claim 5 wherein said nitride layer of said film stack has a thickness of from about 50 to about 300 nm.

12. The method of claim 11 wherein said nitride layer of said film stack has a thickness of from about 100 to about 160 nm.

13. The method of claim 4 wherein said patterned photoresist is formed utilizing a lithography step.

14. The method of claim 13 wherein said lithography step includes applying a photoresist to said film stack, patterning the photoresist by exposure, and developing the pattern in said photoresist.

15. The method of claim 4 wherein said etching step includes a dry etching process selected from the group consisting of reactive-ion etching (RIE), ion-beam etching, plasma etching or any combination thereof.

16. The method of claim 1 wherein said filling step comprises a deposition process selected from the group consisting of CVD, plasma-assisted CVD and sputtering.

17. The method of claim 1 wherein said trench dielectric material is tetraethylorthosilicate (TEOS), SiO₂ or a flowable oxide.

18. The method of claim 17 wherein said trench dielectric material is TEOS and a densification step is employed prior to said planarizing.

19. The method of claim 1 wherein a barrier layer is formed in said at least one trench prior to filling with said trench dielectric material.

20. The method of claim 1 wherein said planarizing step comprises chemical-mechanical polishing or grinding.

21. The method of claim 1 wherein said anneal step is carried out for a time period of 300 seconds or less.

22. The method of claim 1 wherein said anneal step is carried out at a temperature of from about 900°

C. to about 1000°

C. for a time period of from about 5 to about 60 seconds.

23. The method of claim 22 wherein said anneal step is carried out at a temperature of from about 900°

C. to about 950°

C. for a time period of from about 5 to about 20 seconds.

24. The method of claim 1 wherein said anneal step is carried out at atmospheric pressure or in a reduced pressure relative to atmospheric.

25. The method of claim 1 wherein said anneal step is carried out at a pressure of about 100 Torr or less.

26. The method of claim 25 wherein said anneal step is carried out at a pressure of about 10 Torr or less.

27. The method of claim 1 wherein said atmosphere of hydrogen comprises hydrogen alone or hydrogen admixed with an inert gas.

28. The method of claim 27 wherein said inert gas is He, N₂, Ar or mixtures thereof.

29. The method of claim 1 wherein said at least one trench is a shallow isolation trench, a moderate isolation trench, a deep isolation trench or any combinations thereof.

30. The method of claim 29 wherein said at least one trench is a shallow isolation trench.