Low resistivity W using B.sub.2 H.sub.6 nucleation step

• US 6,099,904 A
• Filed: 12/02/1997
• Issued: 08/08/2000
• Est. Priority Date: 12/02/1997
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Mak, Alfred, Lai, Kevin, Leung, Cissy, Sauvage, Dennis
• Primary Examiner(s): MEEKS, TIMOTHY HOWARD
• Application Number:
  US08/982,844
• Time in Patent Office: 980 Days
• Field of Search: 427/250, 427/253, 427/255.1, 427/255.7, 427/255.23, 438/656, 438/680, 438/685
• US Class Current: 427/253
• 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

Abstract

A multiple step chemical vapor deposition process for depositing a tungsten film on a substrate. A first step of the deposition process includes a nucleation step in which a process gas including a tungsten-containing source, a group III or V hydride and a reduction agent are flowed into a deposition zone of a substrate processing chamber while the deposition zone is maintained at or below a first pressure level. During this first deposition stage, other process variables are maintained at conditions suitable to deposit a first layer of the tungsten film over the substrate. Next, during a second deposition stage after the first stage, the flow of the group III or V hydride into the deposition zone is stopped, and afterwards, the pressure in the deposition zone is increased to a second pressure above the first pressure level and other process parameters are maintained at conditions suitable for depositing a second layer of the tungsten film on the substrate. In a preferred embodiment, the flow of the tungsten-containing source is stopped along with the flow of the group III or V hydride and after a period of between 5 and 30 seconds, the flow of the tungsten-containing source is restarted when the pressure is in the deposition zone is increased to the second pressure level.

Claims

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

(a) placing a substrate in a deposition zone;

(b) during a first deposition stage, depositing a first layer of said tungsten film by;

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

(ii) maintaining said deposition zone at or below a first pressure while maintaining other process variables at conditions suitable to deposit said first layer of the tungsten film;

(c) during a second deposition stage after said first stage, depositing a second layer of the tungsten film on said first layer by;

(i) stopping the flow of said group III or V hydride into said deposition zone, and thereafter

(ii) increasing the pressure in said deposition zone to a second pressure above said first pressure while maintaining other process variables at conditions suitable to deposit said second layer of the tungsten film.

2. The chemical vapor deposition process set forth with respect to claim 1 wherein said second deposition stage further comprises:

in step (c)(i), stopping the flow of said tungsten-containing source along with the flow of said group III or V hydride, and

in step (c)(ii), after the pressure in said deposition zone is increased to said second pressure, reflowing said tungsten-containing source into said deposition zone while maintaining other process variables at conditions suitable for depositing the second layer of the tungsten film on the substrate.

3. The chemical vapor deposition process set forth with respect to claim 2 further comprising:

(d) during a third deposition stage, prior to said first deposition stage, flowing a silicon-containing source into said chamber prior to flowing said tungsten-containing source into said chamber during said first deposition stage.

4. The chemical vapor deposition process set forth in claim 3 wherein a hydrogen reducing agent is also flowed into said chamber during said third deposition stage.

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

6. The chemical vapor deposition process set forth in claim 5 wherein said additional reduction agent comprises H₂.

7. The chemical vapor deposition process set forth in claim 2 wherein said process gas introduced during said first and second deposition stages further comprises a nitrogen-containing source.

8. The chemical vapor deposition process set forth in claim 2 wherein said process gas introduced during said first deposition stage further comprises a silicon-containing source and wherein the flow of said silicon-containing source is stopped along with the stoppage of said group III or V halide in step (c)(i).

9. The method of claim 1 wherein said first pressure is between 1 and 50 Torr and said second pressure is between 50 and 760 Torr.

10. The method of claim 1 wherein said first layer of said tungsten film is deposited on a layer of titanium nitride.

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

(a) placing a substrate in a deposition zone;

(b) during a first deposition stage, depositing a first layer of said tungsten film by;

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

(ii) maintaining the deposition zone at a first pressure level below 50 torr and at process conditions suitable to deposit said first layer of the tungsten film on the substrate; and

(c) during a second deposition stage after said first deposition stage, depositing a second layer of said tungsten film on said first layer by;

(i) stopping the flows of said tungsten-containing source, said diborane and said silane gas,

(ii) thereafter, increasing the pressure in the deposition zone to a second pressure level of at least 50 torr, said second pressure level being greater than said first pressure level, and

(iii) between about 5 and 20 seconds after stopping the flows of said gases in step (c)(i), restarting the flow of said tungsten-containing source to deposit said second layer of the tungsten film.

12. The method of claim 11 further comprising a third deposition stage, prior to said first deposition stage, in which a process gas comprising a silane gas, a reduction agent and a carrier gas is flowed into the deposition zone.

13. The method of claim 11 wherein said tungsten-containing source comprises WF₆, said silane gas comprises SiH₄ and said reduction agent comprises H₂.

14. The method of claim 13 wherein said carrier gas comprises argon.

15. The method of claim 13 wherein a nitrogen-containing gas flow is added to said process gas in said first deposition stage and maintained throughout said second deposition stage.

16. The method of claim 11 wherein said diborane gas is diluted in argon at a volume ratio of about 5% diborane:

argon or less.

17. The method of claim 11 wherein said first layer of said tungsten film is deposited on a layer of titanium nitride.

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

placing a substrate in a deposition zone;

prior to a first deposition stage flowing a purge gas including a group III or V hydride and an inert gas into said deposition zone;

during the first deposition stage, depositing a first layer of said tungsten film by flowing a first process gas comprising a tungsten-containing source, a group III or V hydride, and a first reduction agent into said deposition zone, and maintaining said deposition zone at or below a first pressure while maintaining other process variables at conditions suitable to deposit said first layer of the tungsten film;

during a second deposition stage after said first stage, depositing a second layer of the tungsten film on said first layer by flowing a second process gas comprising a tungsten-containing source and a second reduction agent into said deposition zone while maintaining said deposition zone at a pressure above said first pressure and maintaining other process variables at conditions suitable to deposit said second layer of the tungsten film.

19. The chemical vapor deposition process of claim 18 further comprising, prior to flowing said purge gas, flowing a silicon-containing source into the deposition zone and stopping the flow of said silicon-containing source prior to flowing said group III or V hydride and inert gas purge gas.

20. The chemical vapor deposition process of claim 19 wherein said silicon-containing source is flowed for between about 10 and 30 seconds and wherein said purge gas is flowed for between about 10-40 seconds.

21. The method of claim 18 wherein said first reduction agent comprises SiH₄ and said second reduction agent comprises H₂.

22. The method of claim 21 wherein said group III or V hydride in said first process gas is diborane.

23. The method of claim 18 wherein said group III or V hydride in said purge gas is B₂ H₆.

24. A process for depositing a tungsten film over a substrate disposed in a substrate processing chamber, said process comprising:

depositing, at a first pressure level, a first layer of said tungsten film from a first process gas comprising a tungsten-containing source and a group III or V hydride reducing agent; and

depositing, at a second pressure level, a second layer of said tungsten film on said first layer from a second process gas comprising a tungsten-containing source and a first reduction agent, wherein said second pressure level is greater than said first pressure level and said second process gas does not include a group III or V hydride.

25. The method of claim 24 wherein said first pressure is between 1 and 50 Torr and said second pressure is between 50 and 760 Torr.

26. The process of claim 25 wherein said group III or V hydride is diborane.

27. The process of claim 26 wherein said first process gas further comprises a second reducing agent and an inert gas and said second process gas further comprises an inert gas.

28. The process of claim 27 wherein said first and second reducing agents are H₂.

29. The process of claim 28 wherein said first process gas further comprises silane.

30. The process of claim 29 wherein said first layer of said tungsten film is deposited on a layer of titanium nitride.

31. The process of claim 24 wherein said chamber is purged between deposition of said first and second tungsten layers with a purge gas flow.

32. The process of claim 31 wherein the pressure within said chamber is increased to said second pressure level after said chamber is purged with said purge gas.

33. The process of claim 32 wherein said first layer of said tungsten film is deposited on a layer of titanium nitride.