Chemical vapor deposition process for depositing tungsten

• US 6,156,382 A
• Filed: 05/16/1997
• Issued: 12/05/2000
• Est. Priority Date: 05/16/1997
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Yamazaki, Manabu, Ohtsuka, Keiichi, Maeda, Yuji, Rajagopalan, Ravi, Ghanayem, Steve
• Primary Examiner(s): Beck, Shrive
• Assistant Examiner(s): CHEN, BRET P
• Application Number:
  US08/857,658
• Time in Patent Office: 1,299 Days
• Field of Search: 427/250, 427/253, 427/255, 427/255.1, 427/255.28, 427/255.39
• US Class Current: 427/250
• CPC Class Codes: C23C 16/02 Pretreatment of the material to be coated C23C16/04 takes precedence
• CPC Class Codes: C23C 16/0281 of metallic sub-layers C23C16/029 takes precedence
• CPC Class Codes: C23C 16/14 Deposition of only one other metal element
• CPC Class Codes: H01L 21/28556 by chemical means, e.g. CVD, LPCVD, PECVD, laser CVD H01L21/28518 - H01L21/28537 and H01L21/28568 take precedence
• CPC Class Codes: H01L 21/76838 characterised by the formation and the after-treatment of the conductors etching for patterning the conductors H01L21/3213

Abstract

A multiple step chemical vapor deposition process for depositing a tungsten layer on a substrate. A first step of the deposition process includes a nucleation step in which WF₆ and SiH₄ are introduced into a deposition chamber. Next, the flow of WF₆ and SiH₄ are stopped and diborane is introduced into the chamber for between 5-25 seconds. Finally, during a bulk deposition step, the WF₆ is reintroduced into the chamber along with H₂ and B₂ H₆ flows to deposit a tungsten layer on the substrate. In a preferred embodiment, the bulk deposition step also introduces nitrogen into the process gas.

Claims

1. A chemical vapor deposition process for depositing a tungsten film on a substrate, said process comprising:

(a) placing a substrate in a deposition zone;

(b) introducing a tungsten-containing source and a first reduction agent into said deposition zone during a nucleation process stage;

(c) during a first process stage after said nucleation process stage, introducing a group III or V hydride into said deposition zone without introducing a tungsten-containing source into said deposition zone; and

(d) during a second process stage after said first stage,

(i) introducing a process gas comprising a tungsten-containing source, a group III or V hydride and a second reduction agent into said deposition zone, and

(ii) maintaining the deposition zone at process conditions suitable for depositing a tungsten layer on said substrate.

2. The chemical vapor deposition process set forth in claim 1 wherein a third reducing agent comprising H₂ is also introduced into said deposition zone during said third process stage.

3. The chemical vapor deposition process set forth in claim 1 wherein said tungsten-containing source comprises WF₆ and said group III or V hydride comprises B₂ H₆ and said first reduction agent comprises SiH₄.

4. The chemical vapor deposition process set forth in claim 3 wherein said second reduction agent comprises H₂.

5. The process of claim 3 wherein said nucleation process stage also introduces H₂ into said deposition zone as an additional reduction agent.

6. The chemical vapor deposition process set forth in claim 1 wherein said process gas introduced during said second process stage further comprises a nitrogen-containing source.

7. The process of claim 1 wherein said second process stage is a thermal CVD process.

8. The process of claim 1 wherein H₂ is introduced into said deposition zone along with said group III or V hydride during said first process stage.

9. The process of claim 1 wherein a flow of argon is introduced into said deposition zone during said nucleation, said first and said second process stages.

10. A chemical vapor deposition process for depositing a tungsten film on a substrate, said process comprising:

(a) placing a substrate in a process zone;

(b) during a first process stage,

(i) flowing a tungsten-containing gas and a first reduction agent into said deposition zone, and

(ii) maintaining the deposition zone at process conditions suitable for depositing a first tungsten layer on said substrate;

(c) during a second process stage after said first process stage, flowing a diborane gas into said deposition zone for between about 5-20 seconds without flowing a tungsten-containing gas into said deposition zone, and

(d) during a third process stage after said second stage,

(i) flowing a process gas comprising a tungsten-containing source, diborane and a second reduction agent into said deposition zone, and

(ii) maintaining the deposition zone at process conditions suitable for depositing a second tungsten layer over said first layer.

11. The method of claim 10 wherein said second process stage further comprises the step of flowing an inert gas into said deposition zone to purge said deposition zone of residual gases from said first process stage prior to flowing said third stage process gas into said deposition zone.

12. The method of claim 11 wherein said third process stage, process gas further comprises nitrogen.

13. The method of claim 12 wherein during step (i) of said second process stage, said tungsten-containing gas comprises WF₆ and wherein said diborane is diluted in argon at a ratio of about 5% or less.

14. The process of claim 10 wherein said third process stage is a thermal CVD process.

15. The process of claim 10 wherein said first reduction agent comprises SiH₄ and said second reduction agent comprises H₂.

16. A chemical vapor deposition process for depositing a tungsten film on a substrate, said process comprising:

(a) placing a substrate in a deposition zone;

(b) during a first process stage,

(i) introducing a process gas comprising a tungsten-containing source and a first reduction agent into said deposition zone, and

(ii) maintaining the deposition zone at process conditions suitable to deposit a first tungsten layer over said substrate; and

(c) during a second process stage after said first stage,

(i) introducing a process gas comprising a tungsten-containing source, a nitrogen-containing source, a group III or V hydride and a second reduction agent into said deposition zone, and

(ii) maintaining the deposition zone at process conditions suitable for depositing a second tungsten layer over said first tungsten layer.

17. The chemical vapor deposition process set forth with respect to claim 16 wherein said process gas in said second process stage further comprises a nitrogen-containing source.

18. The chemical vapor deposition process set forth with respect to claim 16 further comprising:

(d) an intermediary process stage, between to said first and second process stages, wherein a group III or V hydride is introduced into said deposition zone without introducing a tungsten-containing source.

19. The chemical vapor deposition process set forth with respect to claim 16 wherein said group III or V hydride comprises B₂ H₆.

20. The chemical vapor deposition process set forth with respect to claim 19 wherein said nitrogen-containing source comprises N₂.

21. The process of claim 16 wherein said first reduction agent comprises SiH₄ and said second reduction agent comprises H₂.

22. The process of claim 21 wherein said first process stage further comprises a third reduction agent comprising H₂.

23. A chemical vapor deposition process for depositing a tungsten film on a substrate, said process comprising:

(a) placing a substrate in a process zone;

(b) during a first process stage,

flowing a first process gas comprising WF₆ and SiH₄ into said deposition zone and maintaining the deposition zone at process conditions suitable for depositing a first tungsten layer on said substrate;

(c) during a second process stage after said first process stage, stopping the flow of said first process gas and thereafter, flowing a diborane gas into said deposition zone for between about 5-20 seconds without flowing a tungsten-containing source into said deposition zone; and

(d) during a third process stage after said second stage, flowing a second process gas comprising WF₆, diborane and molecular hydrogen into said deposition zone and maintaining the deposition zone at process conditions suitable for depositing a second tungsten layer over said first layer.