Low resistivity W using B2H6 nucleation step

• US 6,206,967 B1
• Filed: 06/14/2000
• Issued: 03/27/2001
• Est. Priority Date: 12/02/1997
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Lai, Kevin, Leung, Cissy, Sauvage, Dennis, Mak, Alfred
• Primary Examiner(s): Bueker, Richard
• Assistant Examiner(s): FIELER, ERIN L
• Application Number:
  US09/594,234
• Time in Patent Office: 286 Days
• Field of Search: 118/715, 118/723.E, 118/666, 118/668, 427/253, 427/255.23, 438/685, 438/680
• US Class Current: 118/666
• 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 system comprising:

a housing configured to form a vacuum chamber;

a substrate holder, located within said housing, configured to hold a substrate in said vacuum chamber;

a substrate moving system configured to move said substrate into said vacuum chamber and position said substrate on said substrate holder;

a gas delivery system configured to introduce a process gas into said vacuum chamber to deposit a layer over said substrate;

a temperature control system configured to maintain a selected temperature within said vacuum chamber;

a pressure control system configured to maintain a selected pressure within said vacuum chamber;

a controller that controls said substrate moving system, said gas delivery system, said temperature control system and said pressure control system; and

a memory coupled to said controller comprising a computer-readable medium having a computer-readable program embodied therein for directing operation of said chemical vapor deposition system, said computer-readable program comprising;

instructions that control said substrate moving system to move said substrate onto said substrate holder and into said deposition zone;

instructions that control said gas delivery system to flow, during a first deposition stage, a process gas comprising a tungsten-containing source, a group III or V hydride and a reduction agent into said deposition zone;

instructions that control said temperature and pressure control systems to maintain, during said first deposition stage, a selected temperature and pressure within said vacuum chamber that are suitable for depositing a tungsten layer on said substrate, said pressure being maintained at or below a first pressure level;

instructions that control said gas delivery system to, during a second deposition stage subsequent to said first deposition stage, stop the flow of said group III or V hydride and said tungsten-containing source into said deposition zone;

instructions that control said pressure control system to, during said second deposition stage, increase the pressure in said deposition zone to a second pressure above said first pressure; and

a sixth set of instructions for controlling said gas delivery system to, after said pressure is increased to said second pressure, restart the flow of said tungsten-containing source to deposit a second layer of the tungsten film on the substrate.

2. A chemical vapor deposition system comprising:

a housing configured to form a vacuum chamber;

a substrate holder, located within said housing, configured to hold a substrate in said vacuum chamber;

a substrate moving system configured to move said substrate into said vacuum chamber and position said substrate on said substrate holder;

a gas delivery system configured to introduce a process gas into said vacuum chamber to deposit a layer over said substrate;

a temperature control system configured to maintain a selected temperature within said vacuum chamber;

a pressure control system configured to maintain a selected pressure within said vacuum chamber;

a controller that controls said substrate moving system, said gas delivery system, said temperature control system and said pressure control system; and

a memory coupled to said controller comprising a computer-readable medium having a computer-readable program embodied therein for directing operation of said chemical vapor deposition system, said computer-readable program comprising;

instructions that control said substrate moving system to place said substrate in a deposition zone;

instructions that control said gas delivery system to flow, during a first deposition stage, a process gas comprising a tungsten-containing source, a group III or V hydride and an additional reduction agent into said deposition zone;

instructions that control said temperature and pressure control systems to maintain, during said first deposition stage, said deposition zone at or below a first pressure while maintaining other process variables at conditions suitable to deposit a first layer of the tungsten film;

instructions that control said gas delivery system to stop the flow, during a second deposition stage subsequent to said first deposition stage, of said group III or V hydride into said deposition zone; and

instructions that control said pressure control system to increase, during said second deposition stage, the pressure in said deposition zone to a second pressure above said first pressure while maintaining other process variables at conditions suitable to deposit a second layer of the tungsten film.

3. The chemical vapor deposition system of claim 2 wherein:

said instructions that control said gas delivery system during said second deposition stage further comprise instructions for stopping the flow of said tungsten-containing source along with the flow of said group III or V hydride; and

said instructions that control said pressure control system during said second deposition stage further comprise instructions for, 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.

4. The chemical vapor deposition system of claim 3 further comprising:

instructions that control said gas delivery system to flow, during a third deposition stage prior to said first deposition stage, a silicon-containing source into said chamber prior to flowing said tungsten-containing source into said chamber during said first deposition stage.

5. The chemical vapor deposition system of claim 4 wherein said instructions that control said gas delivery system, during said third deposition stage, further comprise instructions for flowing a hydrogen reducing agent into said chamber.

6. The chemical vapor deposition system set of claim 4 wherein said tungsten-containing source comprises WF₆, said group III or V hydride comprises B₂H₆ and said silicon-containing source comprises SiH₄.

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

8. The chemical vapor deposition system set forth in claim 3 wherein said process gas introduced during said first and second deposition stages further comprises a nitrogen-containing source.

9. The chemical vapor deposition system set forth in claim 3 wherein said process gas introduced during said first deposition stage further comprises a silicon-containing source and wherein said fourth set of instructions further comprises instructions for stopping the flow of said silicon-containing source along with the stoppage of said group III or V hydride.

19. The chemical vapor deposition system of claim 2 wherein said first pressure is between 1 and 50 Torr and said second pressure is between 50 and 760 Torr.

20. The chemical vapor deposition system of claim 2 wherein said deposition system is configured to deposit said first layer of said tungsten film onto a layer of titanium nitride.

32. The chemical vapor deposition system of claim 2 wherein said group III or V hydride is B₂H₆.

10. A chemical vapor deposition system comprising:

a housing configured to form a vacuum chamber;

a substrate holder, located within said housing, configured to hold a substrate in said vacuum chamber;

a substrate moving system configured to move said substrate into said vacuum chamber and position said substrate on said substrate holder;

a gas delivery system configured to introduce a process gas into said vacuum chamber to deposit a layer over said substrate;

a temperature control system configured to maintain a selected temperature within said vacuum chamber;

a pressure control system configured to maintain a selected pressure within said vacuum chamber;

a controller that controls said substrate moving system, said gas delivery system, said temperature control system and said pressure control system; and

a memory coupled to said controller comprising a computer-readable medium having a computer-readable program embodied therein for directing operation of said chemical vapor deposition system, said computer-readable program comprising;

instructions that control said substrate moving system to place said substrate in a deposition zone;

instructions that control said gas delivery system to flow, during a first deposition stage, a process gas comprising a tungsten-containing source, diborane, a silane gas, a reduction agent and a carrier gas into the deposition zone;

instructions that control said pressure control system to maintain, during said first deposition stage, said deposition zone at a first pressure level below 50 Torr while maintaining other process variables at conditions suitable to deposit a first layer of the tungsten film on the substrate;

instructions that control said gas delivery system to stop the flow, during a second deposition stage subsequent to said first deposition stage, of said tungsten-containing source, said diborane and said silane gas;

instructions that control said pressure control system to increase, during said second deposition stage, the pressure in the deposition zone to a second pressure of at least 50 Torr; and

instructions that control said gas delivery system to restart the flow, during said second deposition stage and between about 5 and 20 seconds after stopping the flows of said borane and said silane gases, of said tungsten-containing source to deposit a second layer of the tungsten film.

11. The chemical vapor deposition system of claim 10 further comprising:

instructions that control said gas delivery system to flow, during a third deposition stage prior to said first deposition stage, a process gas comprising a silane gas, a reduction agent and a carrier gas into the deposition zone.

12. The chemical vapor deposition system of claim 10 wherein said tungsten-containing source comprises WF₆, said silane gas comprises SiH₄ and said reduction agent comprises H₂.

13. The chemical vapor deposition system of claim 12 wherein said carrier gas comprises argon.

14. The chemical vapor deposition system of claim 12 wherein said process gas includes, in said first deposition stage and throughout said second deposition stage, a nitrogen-containing gas flow.

15. The chemical vapor deposition system of claim 10 wherein said diborane gas is diluted in argon at a volume ratio of about 5% diborane:

argon or less.

21. The chemical vapor deposition system of claim 10 wherein said deposition system is configured to deposit said first layer of said tungsten film onto a layer of titanium nitride.

16. A chemical vapor deposition system comprising:

a housing configured to form a vacuum chamber;

a substrate holder, located within said housing, configured to hold a substrate in said vacuum chamber;

a substrate moving system configured to move said substrate into said vacuum chamber and position said substrate on said substrate holder;

a gas delivery system configured to introduce a process gas into said vacuum chamber to deposit a layer over said substrate;

a temperature control system configured to maintain a selected temperature within said vacuum chamber;

a pressure control system configured to maintain a selected pressure within said vacuum chamber;

a controller that controls said substrate moving system, said gas delivery system, said temperature control system and said pressure control system; and

a memory coupled to said controller comprising a computer-readable medium having a computer-readable program embodied therein for directing operation of said chemical vapor deposition system, said computer-readable program comprising;

instructions that control said substrate moving system to place said substrate in a deposition zone;

instructions that control said gas delivery system to flow, prior to a first deposition stage, a purge gas including a group III or V hydride and an inert gas into said deposition zone;

instructions that control said gas delivery system to flow, during a first deposition stage, a first process gas comprising a tungsten-containing source, and a first reduction agent into said deposition zone;

instructions that control said pressure control system to maintain, during said first deposition stage, said deposition zone at or below a first pressure while maintaining other process variables at conditions suitable to deposit a first layer of the tungsten film;

instructions that control said gas delivery system to flow, during a second deposition stage subsequent to said first deposition stage, a second process gas comprising a tungsten-containing source and a second reduction agent into said deposition zone; and

instructions that control said pressure control system to maintain, during said second deposition stage, the pressure in said deposition zone at a pressure above said first pressure while maintaining other process variables at conditions suitable to deposit a second layer of the tungsten film.

17. The chemical vapor deposition system of claim 16, further comprising:

instructions that control said gas delivery system to flow, prior to flowing said purge gas, a silicon-containing source into the deposition zone; and

instructions that control said gas delivery system to stop the flow, prior to flowing said purge gas of said silicon-containing source.

18. The chemical vapor deposition system of claim 17 wherein:

said seventh set of instructions further comprises instructions for flowing said silicon-containing source for between about 10 and 30 seconds; and

said second set of instructions further comprises instructions for flowing said purge gas for between about 10-40 seconds.

30. The chemical vapor deposition system of claim 16 wherein said first reduction agent comprises SiH₄ and said second reduction agent comprises H₂.

31. The chemical vapor deposition system of claim 30 wherein said first process gas further comprises diborane.

22. A chemical vapor deposition system comprising:

a housing configured to form a vacuum chamber;

a substrate holder, located within said housing, configured to hold a substrate in said vacuum chamber;

a substrate moving system configured to move said substrate into said vacuum chamber and position said substrate on said substrate holder;

a gas delivery system configured to introduce a process gas into said vacuum chamber to deposit a layer over said substrate;

a temperature control system configured to maintain a selected temperature within said vacuum chamber;

a pressure control system configured to maintain a selected pressure within said vacuum chamber;

a controller that controls said substrate moving system, said gas delivery system, said temperature control system and said pressure control system; and

a memory coupled to said controller comprising a computer-readable medium having a computer-readable program embodied therein for directing operation of said chemical vapor deposition system, said computer-readable program comprising;

instructions that control said gas delivery and said pressure control systems to deposit, at a first pressure level, a first layer of tungsten film by flowing a first process gas comprising a tungsten-containing source and a group III or V hydride reducing agent into the vacuum chamber; and

instructions that control said gas delivery and said pressure control systems to deposit, at a second pressure level greater than said first pressure level, a second layer of tungsten film on said first layer by flowing a second process gas comprising a tungsten-containing source and a first reduction agent into the vacuum chamber wherein said second process gas does not include a group III or V hydride.

23. The chemical vapor deposition system of claim 22 wherein said first pressure level is between 1 and 50 Torr and said second pressure level is between 50 and 760 Torr.

24. The chemical vapor deposition system of claim 23 wherein said group III or V hydride is diborane.

25. The chemical vapor deposition system of claim 24 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.

26. The chemical vapor deposition system of claim 25 wherein said first and second reducing agents are H₂.

27. The chemical vapor deposition system of claim 26 wherein said first process gas further comprises silane.

28. The chemical vapor deposition system of claim 22 further comprising a fifth set of instructions for controlling said gas delivery system to flow, between said first and second deposition stages, a purge gas flow whereby said chamber is purged.

29. The chemical vapor deposition system of claim 28 further comprising a sixth set of instructions for controlling said temperature and pressure control systems to increase, after said chamber is purged with said purge gas, the pressure within said chamber to a second pressure level.