Nitrogen treatment of a metal nitride/metal stack

• US 6,436,819 B1
• Filed: 02/01/2000
• Issued: 08/20/2002
• Est. Priority Date: 02/01/2000
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Zhang, Hong, Pung, David, Khurana, Nitin, Zhang, Zhi-Fan, Mosely, Roderick Craig
• Primary Examiner(s): Christianson, Keith
• Assistant Examiner(s): Smoot, Stephen W.
• Application Number:
  US09/495,817
• Time in Patent Office: 931 Days
• Field of Search: 438/656, 438/653, 438/654, 438/658, 438/660, 438/681, 438/685
• US Class Current: 438/656
• CPC Class Codes: H01L 21/76846 Layer combinations
• CPC Class Codes: H01L 21/76856 by treatment in plasmas or gaseous environments, e.g. nitriding a refractory metal liner
• CPC Class Codes: H01L 21/76862 Bombardment with particles, e.g. treatment in noble gas plasmas; UV irradiation

Abstract

A method for processing a substrate comprising the formation of a metal nitride/metal stack suitable for use as a barrier/liner for sub-0.18 μm device fabrication. After a metal nitride layer is deposited upon a metal layer, the metal nitride layer is exposed to a treatment step in a nitrogen-containing environment, e.g., a plasma. The plasma treatment modifies the entire metal nitride layer and a top portion of the underlying metal layer. The plasma adds nitrogen to the top portion of the metal layer, resulting in the formation of a nitrated-metal layer. Aside from reducing the microstructure mismatch across the nitride-metal interface, the plasma treatment also densifies and reduces impurities from the deposited nitride layer. The resulting nitride/metal stack exhibits improved film properties, including enhanced adhesion and barrier characteristics. A composite nitride layer of a desired thickness can also be formed by repeating the deposition and treatment cycles of thinner component nitride layers.

Claims

1. A method of processing a substrate, comprising the steps of:

(a) depositing a nitride layer upon a metal layer to form an interface between said nitride layer and said metal layer, wherein said nitride layer is formed in the presence of a metallo-organic compound comprising titanium;

(b) providing a nitrogen/hydrogen-containing environment; and

(c) modifying said nitride layer and at least a portion of said metal layer below said interface by exposing said nitride layer to said nitrogen/hydrogen-containing environment.

2. The method of claim 1, wherein said metallo-organic compound is tetrakis-dimethylamino-titanium (TDMAT).

3. The method of claim 1, wherein said step (c) comprises adding nitrogen to said portion of said metal layer below said interface.

4. The method of claim 1, wherein said modifying step (c) comprises reducing microstructure mismatch across said interface formed in said step (a).

5. The method of claim 1, wherein said metal layer comprises titanium (Ti), tantalum (Ta) or tungsten (W) and said nitride layer comprises titanium nitride, tantalum nitride or tungsten nitride.

6. The method of claim 1 wherein said nitride layer of said step (a) further comprises carbon or chlorine.

7. The method of claim 6, wherein said modifying step (c) comprises reducing carbon or chlorine from said nitride layer and changing microstructure of said portion of said metal layer below said interface.

8. The method of claim 1, further comprising the steps of:

(d) after step (c), depositing a nitride layer upon said modified nitride layer to form a nitride-nitride interface;

(e) modifying said deposited nitride layer of step (d) and at least a portion of said modified nitride layer from step (c) by exposing said deposited nitride layer to a nitrogen-containing environment.

9. The method of claim 8, wherein said modifying step (e) comprises reducing microstructure mismatch across said nitride-nitride interface of step (d).

10. A method of processing a substrate, comprising the steps of:

(a) depositing a nitride layer upon a metal layer to form an interface between said nitride layer and said metal layer;

(b) providing a nitrogen-containing plasma; and

(c) modifying said nitride layer and at least a portion of said metal layer below said interface by exposing said nitride layer to said nitrogen-containing plasma.

11. The method of claim 10, wherein said nitride layer of said step (a) further comprises carbon or chlorine, and said nitrogen-containing plasma in said step (c) further comprises hydrogen.

12. The method of claim 10, wherein said step (a) is performed in the presence of a metallo-organic compound comprising titanium.

13. The method of claim 12, wherein said metallo-organic compound is tetrakis-dimethylamino-titanium (TDMAT).

14. The method of claim 10, further comprising the steps of:

(d) after step (c), depositing a nitride layer upon said modified nitride layer to form a nitride-nitride interface;

(e) modifying said deposited nitride layer of step (d) and at least a portion of said modified nitride layer from step (c) by exposing said deposited nitride layer to a nitrogen-containing plasma.

15. The method of claim 14, wherein said modifying step (e) comprises reducing microstructure mismatch across said nitride-nitride interface of step (d).

16. A method for processing a substrate, comprising the steps of:

(a) depositing a first nitride layer upon a metal layer to form a first interface between said first nitride layer and said metal layer;

(b) providing a first nitrogen-containing environment;

(c) modifying said first nitride layer of step (a) and at least a portion of said metal layer of step (a) by exposing said first nitride layer to said first nitrogen-containing environment;

wherein nitrogen is added to said portion of said metal layer in the vicinity of-said first interface;

(d) depositing a second nitride layer upon said first nitride layer after said modifying step (c) to form a second interface between said first nitride layer and said second nitride layer;

(e) providing a second nitrogen-containing environment; and

(f) modifying said second nitride layer and at least a portion of said first nitride layer in the vicinity of said second interface by exposing said second nitride layer to said second nitrogen-containing environment.

17. The method of claim 16, wherein said modifying step (c) comprises reducing microstructure mismatch across said first interface between said metal layer and first nitride layer.

18. The method of claim 16, wherein said first nitride layer of said step (a) further comprises carbon or chlorine and said modifying step (c) comprises reducing carbon or chlorine from said first nitride layer.

19. The method of claim 16, wherein said metal layer of step (a) comprises Ti, Ta or W and said first nitride layer comprises TiN, TaN or WN.

20. The method of claim 16, wherein said first nitrogen-containing environment and said second nitrogen-containing environment further comprise hydrogen.

21. The method of claim 16, wherein said modifying step (f) comprises reducing microstructure mismatch across said second interface formed between said first nitride layer and said second nitride layer.

22. The method of claim 16, wherein said first nitrogen-containing environment is a first plasma and said second nitrogen-containing environment is a second plasma.

23. A method for processing a substrate, comprising the steps of:

(a) forming a metal layer upon a substrate;

(b) exposing said metal layer to a first nitrogen-containing environment to form a nitrated-metal layer from at least a top portion of said metal layer;

(c) depositing a nitride layer upon said nitrated-metal layer to form an interface between said nitride layer and said nitrated-metal layer;

(d) modifying said nitride layer and at least a portion of said nitrated-metal layer adjacent said first interface by exposing said nitride layer of said step (c) to a second nitrogen-containing environment.

24. The method of claim 23, further comprising the steps of:

(e) after step (d), depositing a nitride layer upon said plasma-modified nitride layer to form a nitride-nitride interface,

(f) forming a nitrogen-containing plasma; and

(g) modifying said nitride-nitride interface by exposing said deposited nitride layer of step (e) to said nitrogen-containing plasma of step (f).

25. The method of claim 24, wherein said modifying step (g) comprises reducing microstructure mismatch across said nitride-nitride interface.