Titanium tungsten liner used with copper interconnects

Patent metadata

Field	Value
Publication number	US-9685370-B2
Application number	US-201414574889-A
Country	US
Kind code	B2
Filing date	Dec 18, 2014
Priority date	Dec 18, 2014
Publication date	Jun 20, 2017
Grant date	Jun 20, 2017

Abstract

Approaches for providing a liner at a via-to-wire interface are provided. A method includes: forming a via opening that exposes an upper surface of a copper wire; forming a titanium liner on the upper surface of the wire; forming a tungsten liner on the titanium liner; and forming a via on the second liner in the via opening.

First claim

What is claimed is:

1. A method of forming a semiconductor structure, comprising:
forming a via opening that exposes an upper surface of a copper wire;
forming a titanium liner on the upper surface of the wire;
forming a tungsten liner on the titanium liner;
forming a via on the tungsten liner in the via opening;
cleaning exposed surfaces in the via opening with buffered hydrofluoric acid; and
maintaining a wafer comprising the wire in one or more chambers of a processing tool, without exposing the wafer to atmosphere, during the forming the via, the forming the titanium liner, and the forming the tungsten liner,
wherein the via is a tungsten via that has a lower purity than that of the tungsten liner.

2. The method of claim 1 , wherein:
the forming the titanium liner comprises a first ionized physical vapor deposition process; and
the forming the tungsten liner comprises a second ionized physical vapor deposition process.

3. The method of claim 2 , further comprising performing the first ionized physical vapor deposition process and the second ionized physical vapor deposition process without an air break.

4. The method of claim 2 , wherein the forming the via comprises a tungsten chemical vapor deposition process.

5. The method of claim 1 , wherein the forming the via comprises filling the via opening with tungsten on the tungsten liner.

6. The method of claim 1 , wherein the titanium liner and the tungsten liner are devoid of nitride.

7. The method of claim 1 , further comprising heating the wafer to form a copper-titanium alloy region between the wire and the titanium liner.

8. The method of claim 1 , wherein the forming the via opening comprises forming a combined via and interconnect opening in a dual damascene process.

9. The method of claim 1 , wherein:
the titanium liner is on and directly contacting the upper surface of the wire;
the tungsten liner is on and directly contacting the titanium liner; and
the via is on and directly contacting the tungsten liner.

10. The method of claim 9 , wherein:
the titanium liner is pure titanium that is devoid of nitride; and
the tungsten liner is pure tungsten that is devoid of nitride.

11. A method of forming a semiconductor structure, comprising:
forming a copper wire in a first layer of dielectric material;
forming a capping layer on the wire and the first layer of dielectric material;
forming a second layer of dielectric material on the capping layer;
etching a via opening in the second layer of dielectric material and the capping layer to expose an upper surface of the wire;
forming a titanium liner in the via opening and on and directly contacting the upper surface of the wire;
forming a tungsten liner in the via opening and on and directly contacting the titanium liner; and
forming a tungsten via in the via opening and on and directly contacting the tungsten liner,
wherein the tungsten via has a purity lower than a purity of the tungsten liner.

12. The method of claim 11 , wherein:
the forming the titanium liner comprises depositing a layer of pure titanium using a first ionized physical vapor deposition process; and
the forming the tungsten liner comprises depositing a layer of pure tungsten using a second ionized physical vapor deposition process.

13. The method of claim 12 , further comprising performing the first ionized physical vapor deposition process and the second ionized physical vapor deposition process without an air break.

14. The method of claim 11 , further comprising preventing nitrogen poisoning of the titanium liner.

15. The method of claim 11 , wherein the forming the tungsten via comprises filling the via opening with tungsten using a chemical vapor deposition process.

16. The method of claim 11 , further comprising forming a copper-titanium alloy region between the wire and the titanium liner.

17. A semiconductor structure, comprising:
a copper wire in a first layer of dielectric material;
a capping layer on and contacting the wire and the first layer of dielectric material;
a second layer of dielectric material on the capping layer;
a via opening extending through the second layer of dielectric material and the capping layer to an upper surface of the wire;
a titanium liner in the via opening and on and contacting the upper surface of the wire;
a tungsten liner in the via opening and on the titanium liner; and
a tungsten via in the via opening and on the tungsten liner,
wherein the titanium liner is pure titanium that is devoid of nitride;
the tungsten liner is pure tungsten that is devoid of nitride; and
the tungsten via has a lower purity than that of the tungsten liner.

18. The structure of claim 17 , wherein:
the titanium liner directly contacts the wire; and
the tungsten liner directly contacts both the titanium liner and the tungsten via.

19. The structure of claim 17 , further comprising a Cu—Ti alloy region between the titanium liner and the wire.

Assignees

• IBM
• Globalfoundries Inc

Inventors

• Chapple-Sokol Jonathan D
• Christiansen Cathryn J
• Gambino Jeffrey P
• Lee Tom C
• Murphy William J
• Stamper Anthony K

Classifications

• H10W20/425

  Barrier, adhesion or liner layers · CPC title

• H10W20/049

  by diffusing alloying elements · CPC title

• H10W20/47

  comprising two or more dielectric layers having different properties, e.g. different dielectric constants · CPC title

• H10W20/42

  Vias, e.g. via plugs · CPC title

• H10W20/035 Primary

  combinations of barrier, adhesion or liner layers, e.g. multi-layered barrier layers · CPC title