Controlling the shape of source/drain regions in FinFETs

• US 8,362,575 B2
• Filed: 07/07/2010
• Issued: 01/29/2013
• Est. Priority Date: 09/29/2009
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Kwok, Tsz-Mei, Su, Chien-Chang, Chen, Kuan-Yu, Sung, Hsueh-Chang, Lin, Hsien-Hsin
• Primary Examiner(s): HO, HOANG QUAN TRAN
• Application Number:
  US12/831,925
• Publication Number:
  US 20110073952A1
• Time in Patent Office: 937 Days
• Field of Search: None
• US Class Current: 257/401
• CPC Class Codes: H01L 21/76 Making of isolation regions between components
• CPC Class Codes: H01L 29/045 by their particular orientation of crystalline planes
• 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 29/161 including two or more of the elements provided for in group H01L29/16 , e.g. alloys H01L29/1604 takes precedence
• CPC Class Codes: H01L 29/165 in different semiconductor regions , e.g. heterojunctions
• 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 29/7848 the means being located in the source/drain region, e.g. SiGe source and drain
• CPC Class Codes: H01L 29/785 having a channel with a horizontal current flow in a vertical sidewall of a semiconductor body, e.g. FinFET, MuGFET
• CPC Class Codes: H01L 29/7851 with the body tied to the substrate

Abstract

An integrated circuit structure includes a fin field-effect transistor (FinFET) including a semiconductor fin over and adjacent to insulation regions; and a source/drain region over the insulation regions. The source/drain region includes a first and a second semiconductor region. The first semiconductor region includes silicon and an element selected from the group consisting of germanium and carbon, wherein the element has a first atomic percentage in the first semiconductor region. The first semiconductor region has an up-slant facet and a down-slant facet. The second semiconductor region includes silicon and the element. The element has a second atomic percentage lower than the first atomic percentage. The second semiconductor region has a first portion on the up-slant facet and has a first thickness. A second portion of the second semiconductor region, if any, on the down-slant facet has a second thickness smaller than the first thickness.

Claims

1. An integrated circuit structure comprising:

insulation regions comprising top surfaces; and

a fin field-effect transistor (FinFET) comprising;

a semiconductor fin over and adjacent to the insulation regions;

a gate dielectric on a top surface, and extending on sidewalls, of the semiconductor fin;

a gate electrode on the gate dielectric; and

a source/drain region over the insulation regions and adjoining the semiconductor fin, wherein the source/drain region comprises;

a first semiconductor region comprising silicon and an element selected from the group consisting of germanium and carbon, wherein the element has a first atomic percentage in the first semiconductor region, and wherein the first semiconductor region comprises an up-slant facet and a down-slant facet; and

a second semiconductor region comprising silicon and the element, wherein the element has a second atomic percentage in the second semiconductor region with the second atomic percentage being lower than the first atomic percentage, wherein the second semiconductor region comprises a first portion on the up-slant facet and has a first thickness, and wherein a second portion of the second semiconductor region on the down-slant facet has a second thickness smaller than the first thickness.

2. The integrated circuit structure of claim 1, wherein the second atomic percentage is lower than the first atomic percentage by greater than about five percent.

3. The integrated circuit structure of claim 1, wherein the second thickness is less than 20 percent of the first thickness.

4. The integrated circuit structure of claim 1, wherein there is substantially no second portion of the second semiconductor region on the down-slant facet.

5. The integrated circuit structure of claim 1, wherein the up-slant facet and the down-slant facet are on (111) planes.

6. The integrated circuit structure of claim 1 further comprising a silicon interlayer between the first portion of the second semiconductor region and the up-slant facet, and wherein the silicon interlayer extends onto the down-slant facet and contacts the insulation regions.

7. The integrated circuit structure of claim 1 further comprising a SiGe interlayer between the first portion of the second semiconductor region and the up-slant facet, and wherein the SiGe interlayer does not extend onto the down-slant facet.

8. The integrated circuit structure of claim 1, wherein the down-slant facet and the top surfaces of the insulation regions form an angle equal to about 54.7 degrees.

9. An integrated circuit structure comprising:

a silicon substrate;

two shallow trench isolation (STI) regions in the silicon substrate and facing each other, with a portion of the silicon substrate therebetween;

a silicon fin over, and horizontally between, the two STI regions;

a gate dielectric on a top surface, and extending on sidewalls, of the silicon fin;

a gate electrode on the gate dielectric; and

a source/drain stressor comprising at least a portion over and horizontally between the two STI regions, wherein the source/drain stressor contacts the silicon fin and comprises;

a first SiGe region having a first germanium atomic percentage, wherein the first SiGe region comprises an up-slant facet on a (111) plane, and a down-slant facet on an additional (111) plane; and

a second SiGe region with a second germanium atomic percentage lower than the first germanium atomic percentage, wherein the second SiGe region comprises a portion on the up-slant facet, and wherein substantially no portion of the second SiGe region extends on the down-slant facet.

10. The integrated circuit structure of claim 9, wherein the second germanium atomic percentage is lower than the first germanium atomic percentage by greater than about five percent.

11. The integrated circuit structure of claim 9 further comprising a silicon interlayer between the second SiGe region and the up-slant facet, and wherein the silicon interlayer extends onto the down-slant facet and contacts one of the two STI regions.

12. The integrated circuit structure of claim 9 further comprising a SiGe interlayer between the second SiGe region and the up-slant facet, and wherein the SiGe interlayer does not extends onto the down-slant facet.

13. The integrated circuit structure of claim 9, wherein the down-slant facet and top surfaces of the two STI regions form an angle equal to about 54.7 degrees.

14. An integrated circuit structure comprising:

a silicon substrate;

two shallow trench isolation (STI) regions in the silicon substrate and facing each other, with a portion of the silicon substrate therebetween;

a silicon fin over, and horizontally between, the two STI regions;

a gate dielectric on a top surface, and extending on sidewalls, of the silicon fin;

a gate electrode on the gate dielectric; and

a source/drain stressor comprising at least a portion over and horizontally between the two STI regions, wherein the source/drain stressor contacts the silicon fin and comprises;

a first SiGe region having a first germanium atomic percentage of germanium to silicon and germanium, wherein the first SiGe region has an up-slant facet on a (111) plane, and a down-slant facet on an additional (111) plane; and

a first germano-silicide with a second germanium atomic percentage of germanium to silicon and germanium, wherein the second germanium atomic percentage is lower than the first germanium atomic percentage, and wherein the first germano-silicide is on the up-slant facet.

15. The integrated circuit structure of claim 14, wherein the second germanium atomic percentage is lower than the first germanium atomic percentage by greater than about five percent.

16. The integrated circuit structure of claim 14, wherein the first germanium atomic percentage is greater than about 20 percent, and the second germanium atomic percent is lower than about 10 percent.

17. The integrated circuit structure of claim 14 further comprising an additional SiGe region between the first germano-silicide and the up-slant facet, wherein the additional SiGe region and the first germano-silicide have a same germanium atomic percentage of germanium to germanium and silicon.

18. The integrated circuit structure of claim 14, wherein the down-slant facet and top surfaces of the two STI regions form an angle equal to about 54.7 degrees.