Method for fabricating thermally stable contacts with a diffusion barrier formed at high temperatures

• US 5,913,145 A
• Filed: 08/28/1997
• Issued: 06/15/1999
• Est. Priority Date: 08/28/1997
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Cho, Chih-Chen, Lu, Jiong-Ping
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): Zarneke, David A.
• Application Number:
  US08/920,303
• Time in Patent Office: 656 Days
• Field of Search: 438/643, 438/648, 438/649, 438/653, 438/655, 438/656, 438/660, 438/663, 438/664, 438/680, 438/682, 438/683, 438/FOR 407, 438/927
• US Class Current: 438/643
• CPC Class Codes: C23C 16/08 from metal halides
• CPC Class Codes: C23C 16/16 from metal carbonyl compounds
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76855 After-treatment introducing at least one additional element into the layer
• CPC Class Codes: Y10S 438/927 Electromigration resistant metallization

Abstract

In order to provide a thermally stable diffusion barrier for a contact, a layer of titanium is formed on the patterned substrate. A layer of tungsten nitride is formed on the titanium layer. After an annealing step, an interfacial layer and a layer of titanium nitride are formed between the substrate and a tungsten layer. These layers provide a diffusion barrier which is more thermally stable than a titanium nitride layer applied directly on the substrate and permits the formation of a contact structures that can withstand subsequent high temperature steps.

Claims

1. A method of forming a diffusion barrier layer for a contact structure, said method comprising the steps of:

forming a layer of titanium on a patterned substrate;

forming a layer of tungsten nitride on said titanium layer;

annealing said layers along with said substrate to form a titanium nitride layer and a tungsten layer.

2. The method of claim 1 wherein titanium is replaced by an element selected from the group consisting of cobalt and nickel.

3. The method of claim 1 wherein said titanium layer is replaced by an MSi_x layer or MSi_x /M layers, wherein M is a metal selected from the group consisting of titanium, cobalt and nickel.

4. The method of claim 1 wherein said titanium layer is formed using a CVD process based on the chemical process

5. The method of claim 1 wherein said tungsten nitride layer is formed using CVD process based on a chemical process selected from the group of chemical processes consisting of:

space="preserve" listing-type="equation">WF.sub.6 +NH.sub.3 +H.sub.2 →

WN.sub.x +HF,

space="preserve" listing-type="equation">WF.sub.6 +N.sub.2 +H.sub.2 →

WN.sub.x +HF, and

space="preserve" listing-type="equation">W(CO).sub.6 +NH.sub.3 →

WN.sub.x +CO+H.sub.2.

6. The method of claim 1 wherein said titanium and/or said tungsten nitride layer are prepared by physical vapor deposition.

7. The method of claim 1 wherein an additional tungsten layer is added after said annealing step.

8. A method for forming a contract structure, said method comprising the steps of:

forming a titanium layer on a substrate;

forming a tungsten nitride layer on said titanium layer,

forming a tungsten layer on said tungsten nitride layer; and

annealing the structure resulting from a formation of these layers to form a titanium nitride layer and a tungsten layer.

9. The method of claim 8 wherein titanium is replaced by an element selected from the group consisting of cobalt and nickel.

10. The method of claim 8 wherein said titanium layer is replaced by one of an MSi_x layer or a MSi_x /M layers, where M is selected from the group consisting of titanium, cobalt, or nickel.

11. The method of claim 8 wherein said titanium layer is formed using a CVD process based on the chemical process

12. The method of claim 8 wherein said tungsten nitride layer is formed using CVD process based on a chemical process selected from the group of chemical processes consisting of:

space="preserve" listing-type="equation">WF.sub.6 +NH.sub.3 +H.sub.2 →

WN.sub.x +HF,

space="preserve" listing-type="equation">WF.sub.6 +N.sub.2 +H.sub.2 →

WN.sub.x +HF, and

space="preserve" listing-type="equation">W(CO).sub.6 +NH.sub.3 →

WN.sub.x +CO+H.sub.2.

13.

13. The method of claim 8 wherein said titanium and/or said tungsten nitride layers are prepared by physical vapor deposition.