Method to improve copper barrier properties

• US 6,403,465 B1
• Filed: 12/28/1999
• Issued: 06/11/2002
• Est. Priority Date: 12/28/1999
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Liu, Chung-Shi, Yu, Chen-Hua
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): GURLEY, LYNNE ANN
• Application Number:
  US09/473,033
• Time in Patent Office: 896 Days
• Field of Search: 438/627-629, 438/631, 438/633, 438/637-638, 438/643-645, 438/648, 438/653-654, 438/656, 438/672, 438/675, 438/680, 438/685, 438/687
• US Class Current: 438/627
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76846 Layer combinations
• CPC Class Codes: H01L 21/76873 for electroplating

Abstract

A method is disclosed to improve copper barrier and adhesion properties of copper interconnections in integrated circuits. It is shown that combining ion metal plasma (IMP) deposition along with in-situ chemical vapor deposition (CVD) of barrier and adhesion materials provides the desired adhesion of and barrier to diffusion of copper in damascene structures. IMP deposition is performed with tantalum or tantalum nitride while CVD deposition is performed with a binary or a ternary compound from a group consisting of titanium nitride, tungsten nitride, tungsten silicon nitride, tantalum silicon nitride, titanium silicon nitride. IMP deposition provides good adhesion of copper to insulator materials, while CVD deposition provides good sidewall coverage in a copper filled trench and a copper seed layer provides good adhesion of bulk copper to adhesion/barrier layer. The IMP/CVD deposited adhesion/barrier layer is thin, thus providing low via resistance.

Claims

1. A method to improve copper barrier properties comprising the steps of:

providing a semiconductor substrate having a substructure comprising devices formed in said substrate and a metal layer formed thereon;

forming an inter level dielectric (ILD) layer over said substrate;

patterning and etching said ILD layer to form a trench with inside walls therein;

performing in-situ PVD/CVD deposition of a diffusion barrier layer along with ion metal plasma (IMP) deposition of an adhesion layer to form a combined (adhesion+barrier) layer on said substrate including inside walls of said trench;

forming a metal seed layer over said substrate including over said (adhesion+barrier) layer;

forming a second metal layer over said substrate including over said metal seed layer; and

removing any excess second metal layer from said substrate.

2. The method of claim 1, wherein said substrate is silicon.

3. The method of claim 1, wherein said ILD layer comprises an oxide or a polyimide.

4. The method of claim 1, wherein said ILD layer has a thickness between about 5000 to 12000 Å

.

5. The method of claim 1, wherein said trench has a depth between about 5000 to 12000 Å

.

6. The method of claim 1, wherein said in-situ PVD/CVD deposition of a diffusion barrier layer along with ion metal plasma (IMP) deposition of an adhesion layer to form a combined (adhesion+barrier) layer is accomplished with material taken from the group consisting of titanium nitride, tungsten nitride, tungsten silicon nitride, tantalum silicon nitride, titanium silicon nitride or other ternary compound at a pressure between about 1 to 10000 mtorr, temperature between about 20 to 450°

C., with energy between about 0.5 to 2 KW.

7. The method of claim 1, wherein said (adhesion+diffusion) layer has a thickness between about 50 to 300 Å

.

8. The method of claim 1, wherein said forming a metal seed layer is accomplished by IMP deposition of copper or by CVD deposition of copper.

9. The method of claim 1, wherein said metal seed layer has a thickness between about 500 to 2000 Å

.

10. The method of claim 1, wherein said forming a second metal layer is accomplished by depositing copper.

11. The method of claim 1, wherein said removing said excess second metal is accomplished by chemical-mechanical polishing.