Metal gate scheme for device and methods of forming

• US 10,522,640 B2
• Filed: 04/05/2018
• Issued: 12/31/2019
• Est. Priority Date: 04/30/2015
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: JangJian, Shiu-Ko, Liu, Chi-Wen, Wu, Chih-Nan, Lin, Chun Che
• Primary Examiner(s): Kraig, William F
• Assistant Examiner(s): Booker, Vicki B.
• Application Number:
  US15/945,799
• Publication Number:
  US 20180226485A1
• Time in Patent Office: 635 Days
• CPC Class Codes: H01L 21/28088 the final conductor layer next to the insulator being a composite, e.g. TiN
• CPC Class Codes: H01L 21/823842 gate conductors with different gate conductor materials or different gate conductor implants, e.g. dual gate structures
• CPC Class Codes: H01L 29/165 in different semiconductor regions , e.g. heterojunctions
• 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
• CPC Class Codes: H01L 29/66545 using a dummy, i.e. replacement gate in a process wherein at least a part of the final gate is self aligned to the dummy gate
• CPC Class Codes: H01L 29/66636 with source or drain recessed by etching or first recessed by etching and then refilled
• CPC Class Codes: H01L 29/7834 with a non-planar structure, e.g. the gate or the source or the drain being non-planar
• CPC Class Codes: H01L 29/7848 the means being located in the source/drain region, e.g. SiGe source and drain

Abstract

Gate structures and methods of forming the gate structures are described. In some embodiments, a method includes forming source/drain regions in a substrate, and forming a gate structure between the source/drain regions. The gate structure includes a gate dielectric layer over the substrate, a work function tuning layer over the gate dielectric layer, a first metal over the work function tuning layer, an adhesion layer over the first metal, and a second metal over the adhesion layer. In some embodiments, the adhesion layer can include an alloy of the first and second metals, and may be formed by annealing the first and second metals. In other embodiments, the adhesion layer can include an oxide of at least one of the first and/or second metal, and may be formed at least in part by exposing the first metal to an oxygen-containing plasma or to a natural environment.

Claims

1. A structure comprising:

a first source/drain region and a second source/drain region in a substrate;

a gate structure on the substrate and between the first source/drain region and the second source/drain region, the gate structure comprising;

a gate dielectric layer over the substrate,

a work function tuning layer over the gate dielectric layer,

a first metal over the work function tuning layer,

an adhesion layer over the first metal, and

a second metal over the adhesion layer, the second metal being different from the first metal, wherein the adhesion layer comprises a first oxide; and

an inter-layer dielectric over the substrate and around the gate structure.

2. The structure of claim 1, wherein the first oxide comprises an oxide of the first metal.

3. The structure of claim 1, wherein the first oxide comprises an oxide of an alloy of the first metal and the second metal.

4. The structure of claim 1, wherein the first oxide comprises an oxide of the second metal.

5. The structure of claim 1 further comprising:

a buffer layer over the gate structure, the buffer layer comprising an oxide of the first metal and an oxide of the second metal; and

a dielectric cap over the buffer layer, a top surface of the dielectric cap being co-planar with a top surface of the inter-layer dielectric.

6. The structure of claim 1, wherein an upper surface of the second metal is recessed below an upper surface of the inter-layer dielectric.

7. The structure of claim 1, wherein the adhesion layer is between about 10 Å

and about 50 Å

.

8. A structure comprising:

a first source/drain region;

a second source/drain region;

a channel region interposed between the first source/drain region and the second source/drain region;

an inter-layer dielectric over the first source/drain region and the second source/drain region;

a gate structure over the channel region, the gate structure comprising;

a gate dielectric layer;

a work function tuning layer over the gate dielectric layer;

a first metal over the work function tuning layer;

an adhesion layer over the first metal; and

a second metal over the adhesion layer, wherein the adhesion layer comprises;

an oxide of the first metal and the second metal;

an oxide of the second metal over an oxide of the first metal;

or

an alloy of the first metal and the second metal.

9. The structure of claim 8, wherein the adhesion layer is between about 10 Å

and about 50 Å

.

10. The structure of claim 8, wherein the first metal comprises Co.

11. The structure of claim 10, wherein the second metal comprises Al.

12. The structure of claim 8, further comprising an oxide layer interposed between gate dielectric layer and the channel region.

13. The structure of claim 12, further comprising a capping layer interposed between the gate dielectric layer and the oxide layer.

14. The structure of claim 13, wherein the capping layer comprises a TiN layer.

15. The structure of claim 14, wherein the capping layer comprises a TaN layer over the TiN layer.

16. A structure comprising:

a substrate;

a channel region in the substrate, the channel region being interposed between a first source/drain region and a second source/drain region;

a gate structure over the channel region, the gate structure comprising;

a gate dielectric layer;

a work function tuning layer over the gate dielectric layer;

a first metal layer over the work function tuning layer;

an adhesion layer over the first metal layer, wherein the adhesion layer comprises an alloy or oxide of the first metal layer; and

a second metal layer over the adhesion layer.

17. The structure of claim 16, wherein the adhesion layer comprises an oxide of the second metal layer.

18. The structure of claim 16, further comprising a first dielectric layer adjacent the gate structure, wherein the first dielectric layer extends above an upper surface of the gate structure.

19. The structure of claim 18, further comprising one or more second dielectric layers overlying the gate structure, wherein an uppermost surface of the one or more second dielectric layers is level an upper surface of the first dielectric layer.

20. The structure of claim 16, wherein an uppermost surface of the first metal layer is level with an uppermost surface of the second metal layer.