Metal gate stack with etch stop layer

• US 6,664,604 B1
• Filed: 10/18/2002
• Issued: 12/16/2003
• Est. Priority Date: 04/03/2001
• Status: Active Grant

• Current Assignee: Globalfoundries US Incorporated (GlobalFoundries, Inc.)
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Dakshina-Murthy, Srikanteswara, Besser, Paul R.
• Primary Examiner(s): Le, Vu A.
• Assistant Examiner(s): Wilson, Christian D.
• Application Number:
  US10/273,306
• Time in Patent Office: 424 Days
• Field of Search: 257/412, 438/654, 438/656, 438/737, 438/738, 438/742
• US Class Current: 257/412
• CPC Class Codes: H01L 21/28088 the final conductor layer next to the insulator being a composite, e.g. TiN
• CPC Class Codes: H01L 29/4966 the conductor material next to the insulator being a composite material, e.g. organic material, TiN, MoSi2 H01L29/4908, H01L29/4983 take precedence

Abstract

A metal gate structure and method of forming the same employs an etch stop layer between a first metal layer, made of TiN, for example, and the metal gate formed of tungsten. The etch stop layer prevents overetching of the TiN during the etching of the tungsten in the formation of the metal gate. The prevention of the overetching of the TiN protects the gate oxide from undesirable degradation. The provision of aluminum or tantalum in the etch stop layer allows a thin etch stop layer to be used that provides adequate etch stopping capability and does not undesirably affect the work function of the TiN.

Claims

1. A metal gate structure, comprising:

a gate oxide;

a first metal layer on the gate oxide;

an etch stop layer on the first metal layer; and

a second metal layer on the etch stop layer.

2. The metal gate structure of claim 1, wherein the first metal layer comprises TiN and the second metal layer comprises tungsten.

3. The metal gate structure of claim 2, wherein the etch stop layer comprises tantalum.

4. The metal gate structure of claim 2, wherein the etch stop layer comprises aluminum.

5. The metal gate structure of claim 2, wherein the etch stop layer comprises at least one of aluminum and tantalum.

6. The metal gate structure of claim 5, wherein the gate oxide has a thickness of between about 15 to about 30 Å

ngstroms, the first metal layer has a thickness of between about 100 to about 200 Å

ngstroms, the etch stop layer has a thickness of between about 100 to about 300 Å

ngstroms, and the second metal layer has a thickness of between about 500 to about 1,000 Å

ngstroms.

7. A metal gate structure comprising:

a gate oxide;

a TiN layer on the gate oxide;

an etch stop layer comprising at least one of aluminum and tantalum on the TiN layer; and

a tungsten layer on the etch stop layer.

8. The metal gate structure of claim 7, wherein the gate oxide has a thickness of between about 15 to about 30 Å

ngstroms, the TiN layer has a thickness of between about 100 to about 200 Å

ngstroms, the etch stop layer has a thickness of between about 100 to about 300 Å

ngstroms, and the tungsten layer has a thickness of between about 500 to about 1,000 Å

ngstroms.