FinFETs and methods for forming the same

• US 9,349,841 B2
• Filed: 02/19/2015
• Issued: 05/24/2016
• Est. Priority Date: 02/27/2013
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Huang, Yu-Lien, Fan, Chun-Hsiang, Perng, Tsu-Hsiu, Liu, Chi-Kang, Li, Yung-Ta, Tsai, Ming-Huan, Wann, Clement Hsingjen, Liu, Chi-Wen
• Primary Examiner(s): Monbleau, Davienne
• Assistant Examiner(s): Erdem, Fazli
• Application Number:
  US14/625,848
• Publication Number:
  US 20150171187A1
• Time in Patent Office: 460 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 21/30604 Chemical etching
• CPC Class Codes: H01L 21/3247 for altering the shape, e.g. smoothing the surface
• CPC Class Codes: H01L 29/0653 adjoining the input or output region of a field-effect device, e.g. the source or drain region
• CPC Class Codes: H01L 29/34 the imperfections being on the surface
• 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 29/66795 with a horizontal current flow in a vertical sidewall of a semiconductor body, e.g. FinFET, MuGFET
• CPC Class Codes: H01L 29/6681 using dummy structures having essentially the same shape as the semiconductor body, e.g. to provide stability
• CPC Class Codes: H01L 29/7853 the body having a non-rectangular crossection

Abstract

A finFET and methods for forming a finFET are disclosed. A structure comprises a substrate, a fin, a gate dielectric, and a gate electrode. The substrate comprises the fin. The fin has a major surface portion of a sidewall, and the major surface portion comprises at least one lattice shift. The at least one lattice shift comprises an inward or outward shift relative to a center of the fin. The gate dielectric is on the major surface portion of the sidewall. The gate electrode is on the gate dielectric.

Claims

1. A method comprising:

forming a fin on a substrate;

after forming the fin, re-shaping the fin to have a surface portion of each sidewall of the fin with a plurality of lattice shift locations, the surface portion of each sidewall extending from the to of each sidewall, each of the plurality of lattice shift locations comprising an inward or outward shift relative to a center of the fin;

forming a dielectric on the surface portion of the sidewall; and

forming a gate electrode on the dielectric.

2. The method of claim 1, wherein the re-shaping the fin comprises a wet etch.

3. The method of claim 1, wherein the re-shaping the fin comprises a dry etch.

4. The method of claim 1, wherein the re-shaping the fin comprises an anneal.

5. The method of claim 1, wherein the re-shaping the fin increases a surface roughness of the fin.

6. The method of claim 1 further comprising:

forming a dummy dielectric on the fin;

forming a dummy gate on the dummy dielectric; and

removing the dummy gate and the dummy dielectric, the re-shaping the fin being performed after removing the dummy gate and the dummy dielectric.

7. The method of claim 1, wherein the plurality of lattice shift locations comprises a plurality of inward lattice shifts relative to the center of the fin when traversing the plurality of lattice shifts in a direction away from the substrate.

8. The method of claim 1, wherein the plurality of lattice shift locations comprises a plurality of outward lattice shifts relative to the center of the fin when traversing the plurality of lattice shifts in a direction away from the substrate.

9. The method of claim 1, wherein the plurality of lattice shift locations comprises a combination of inward lattice shifts and outward lattice shifts relative to the center of the fin.

10. A method comprising:

forming a fin on a substrate, the fin having a first exterior side surface in a channel region of the fin;

increasing a surface roughness of the fin in the channel region by re-shaping the entire surface of the channel region of the fin to have a second exterior side surface with a plurality of lattice shifts;

forming a gate dielectric on the second exterior side surface in the channel region; and

forming a gate electrode on the gate dielectric.

11. The method of claim 10, wherein the increasing the surface roughness of the fin comprises using a wet etch.

12. The method of claim 10, wherein the increasing the surface roughness of the fin comprises using a dry etch.

13. The method of claim 10, wherein the increasing the surface roughness of the fin comprises using an anneal.

14. The method of claim 10 further comprising:

forming a dummy dielectric on the first exterior side surface in the channel region;

forming a dummy gate on the dummy dielectric; and

removing the dummy gate and the dummy dielectric, the increasing the surface roughness of the fin being performed after the removing.

15. The method of claim 10, wherein the second exterior side surface further extends to a region of the fin outside of the channel region.

16. A method comprising:

forming a fin in a substrate, the fin being proximate an isolation region, the fin having a first exterior surface protruding above the isolation region;

forming a dummy dielectric on the first exterior surface of the fin;

forming a dummy gate on the dummy dielectric;

removing the dummy gate and the dummy dielectric;

after the removing, causing the fin to have a second exterior surface protruding above the isolation region, the second exterior surface deviating from the first exterior surface by a plurality of lattice shifts and comprising a portion of a top surface of the fin and a portion of a sidewall of the fin;

forming a gate dielectric on the second exterior surface; and

forming a gate electrode on the gate dielectric.

17. The method of claim 16, wherein the causing the fin to have the second exterior surface comprises a wet etch, a dry etch, an anneal, or a combination thereof.

18. The method of claim 16, wherein the second exterior surface has a greater surface roughness than the first exterior surface.

19. The method of claim 16, wherein the plurality of lattice shifts comprises a first lattice shift and a second lattice shift, the second lattice shift being distally located from the isolation region relative to the first lattice shift, the first lattice shift being an inward lattice shift relative to a center line of the fin when traversing the plurality of lattice shifts in a direction from the first lattice shift to the second lattice shift, the second lattice shift being an outward lattice shift relative to the center line of the fin when traversing the plurality of lattice shifts in the direction.

20. The method of claim 16, wherein each of the plurality of lattice shifts is an inward lattice shift relative to a center line of the fin when traversing the plurality of lattice shifts in a direction from proximate the isolation region to distally from the isolation region.