In-situ capped aluminum plug (CAP) process using selective CVD AL for integrated plug/interconnect metallization

• US 6,110,828 A
• Filed: 12/30/1996
• Issued: 08/29/2000
• Est. Priority Date: 12/30/1996
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Chen, Liang-Yuh, Guo, Ted, Subrahmanyan, Suchitra
• Primary Examiner(s): Everhart, Caridad
• Application Number:
  US08/791,653
• Time in Patent Office: 1,338 Days
• Field of Search: 438/627, 438/634, 438/637, 438/641, 438/648, 438/688, 438/680, 438/681, 438/685, 438/653, 438/654, 438/656, 438/672
• US Class Current: 438/688
• CPC Class Codes: H01L 21/76879 by selective deposition of conductive material in the vias, e.g. selective C.V.D. on semiconductor material, plating plating on semiconductors in general H01L21/288

Abstract

The present invention generally provides a method of forming a structure having a selective CVD metal plug with a continuous barrier layer formed thereon. More particularly, the present invention applies a thin layer of warm PVD metal over a selective CVD metal plug and adjacent nodules on the dielectric field to planarize the metal surface. A barrier is then deposited over the planarized metal surface. Therefore, the invention provides the advantages of having (1) void-free, sub-half micron selective CVD metal via plugs and interconnects, and (2) a reduced number of process steps without the use of CMP, and (3) barrier layers over the metal plugs to improve the electromigration resistance of the metal.

Claims

1. A method of forming a capped metal plug in a via through a dielectric layer, wherein the via has a floor exposing a deposition enhancing material, comprising the steps of:

a) selectively chemical vapor depositing a metal on the deposition enhancing material of the via floor to form a plug in the via;

b) physical vapor depositing a sufficient amount of a warm metal over the dielectric layer to substantially planarize any nodules on the dielectric layer, wherein the physical vapor deposited metal has a thickness below about 1200 Å

; and

c) depositing a barrier layer over the physical vapor deposited metal.

2. The method of claim 1, wherein the selectively chemical vapor deposited metal is CVD Al.

3. The method of claim 2, wherein the warm PVD metal is warm PVD Al.

4. The method of claim 2, wherein the warm PVD metal is warm PVD AlCu.

5. The method of claim 2, wherein the warm PVD metal is deposited at a temperature between about 350°

C. and about 500°

C.

6. The method of claim 5, wherein the warm PVD metal is deposited at a temperature of about 400°

C.

7. The method of claim 1, wherein the barrier layer comprises a metal selected from the group consisting of titanium, titanium nitride, tantalum and tantalum nitride.

8. The method of claim 1, wherein the barrier layer comprises a first sublayer of titanium, a second sublayer of titanium nitride and a third sublayer of titanium.

9. The method of claim 1 further comprising the step of:

(d) depositing a second metal layer over the barrier layer.

10. The method of claim 9, wherein the second metal layer is comprised of PVD Al, CVD Al, Cu or combinations thereof.

11. The method of claim 1, further comprising the step of:

(d) forming a metal interconnect over the barrier layer.

12. The method of claim 11, wherein the metal interconnect comprises aluminum.

13. The method of claim 1, wherein steps (a) through (c) are performed in an integrated processing system comprising a chemical vapor deposition chamber and a physical vapor deposition chamber.

20. The method of claim 1, wherein the physical vapor deposited metal has a thickness from about 100 Å

to about 1200 Å

.

21. The method of claim 1, wherein the physical vapor deposited metal has a thickness less than the depth of the via.

14. A method of forming a via plug through a dielectric layer having barrier layers at each end of the plug, comprising the steps of:

a) depositing a barrier layer on the top layer of a workpiece;

b) forming a dielectric layer over the barrier layer;

c) etching a via through the dielectric layer to form a floor exposing the barrier layer;

d) selectively chemical vapor depositing a conductive material on the exposed portion of the barrier layer to form a plug in the via;

e) physical vapor depositing a sufficient amount of a warm metal over the dielectric layer to substantially planarize any nodules formed by loss of selectivity during plug formation, wherein the warm physical vapor deposited metal has a thickness from about 100 Å

to about 1200 Å

; and

f) depositing a barrier cap layer over the warm physical vapor deposited metal.

15. The method of claim 14, wherein both barrier layers comprise a metal selected from the group consisting of titanium, titanium nitride, tantalum and tantalum nitride.

16. The method of claim 14, further comprising the step of:

(g) depositing a second metal layer over the barrier cap layer.

17. The method of claim 14, further comprising the step of:

(g) depositing a second metal layer over the barrier cap layer; and

(h) depositing another barrier layer over the second metal layer.

18. The method of claim 17, further comprising the step of repeating steps (b) through (h).

19. The method of claim 16, wherein the second metal layer comprises PVD Al.

22. The method of claim 14, wherein the warm physical vapor deposited metal has a thickness less than the depth of the via.