FinFET with an asymmetric source/drain structure and method of making same

1. A semiconductor device comprising:

a first semiconductor fin extending above a substrate;

a first source region on the first semiconductor fin, the first source region having a first width;

a first drain region on the first semiconductor fin, the first drain region having a second width, the second width being different than the first width;

a first channel region in the first semiconductor fin interposed between the first source region and the first drain region, the first channel region being doped with impurities of a first conductivity type;

a first active gate on a top surface and sidewalls of the first channel region in the first semiconductor fin, the first active gate being interposed between the first source region and the first drain region;

a first dummy gate on the top surface and sidewalls of the first semiconductor fin, the first dummy gate being on a first end of the first semiconductor fin adjacent the first source region; and

a second dummy gate on the top surface and sidewalls of the first semiconductor fin, the second dummy gate being on a second end of the first semiconductor fin adjacent the first drain region, the second end of the first semiconductor fin being opposite the first end.

2. The semiconductor device of claim 1 , wherein the first width is larger than the second width.

3. The semiconductor device of claim 1 , wherein the first width is from about 1.2 to about 5 times larger than the second width.

4. The semiconductor device of claim 1 further comprising:

a first source contact over and electrically coupled to the first source region, the first source contact having a third width; and

a first drain contact over and electrically coupled to the first drain region, the first drain contact having a fourth width, the fourth width being different than the third width.

5. The semiconductor device of claim 4 , wherein the third width is from about 1.2 to about 5 times larger than the fourth width.

6. The semiconductor device of claim 4 , wherein the first source contact and the first drain contact comprise material selected from a group consisting essentially of aluminum, copper, tungsten, or a combination thereof.

7. The semiconductor device of claim 1 , wherein the first source region and the first drain region both comprise an epitaxial layer.

8. The semiconductor device of claim 1 further comprising:

a second semiconductor fin extending above the substrate, the second semiconductor fin being parallel to the first semiconductor fin;

a second source region on the second semiconductor fin, the second source region having the first width;

a second drain region on the second semiconductor fin, the second drain region having the second width; and

a second gate over the second semiconductor fin, wherein the second gate is interposed between the second source region and the second drain region.

9. The semiconductor device of claim 8 further comprising:

a second source contact over and electrically coupled to the second source region, the second source contact having a third width; and

a second drain contact over and electrically coupled to the second drain region, the second drain contact having a fourth width, the third width being larger than the fourth width.

10. The semiconductor device of claim 1 , wherein the first source region is in a recess in the first semiconductor fin, and wherein the first source region has a top surface above the top surface of the first semiconductor fin.

11. A FinFET device comprising:

a first plurality of fins extending above a substrate, the first plurality of fins having first longitudinal axes;

a first source region on the first plurality of fins, the first source region having a first width measured in a direction substantially parallel to the first longitudinal axes, the first source region having a top surface above top surfaces of the first plurality of fins;

a first drain region on the first plurality of fins, the first drain region having a second width measured in a direction substantially parallel to the first longitudinal axes, the first width being larger than the second width, the first source region having a top surface above top surfaces of the first plurality of fins, the first source region and the first drain region having top surfaces that are substantially coplanar;

a first channel region in the first plurality of fins, the first channel region being interposed between the first source region and the first drain region, the first channel region being doped with impurities of a first conductivity type;

a first source contact over and electrically coupled to the first source region, the first source contact having a third width;

a first drain contact over and electrically coupled to the first drain region, the first drain contact having a fourth width, the fourth width being smaller than the third width;

a first dummy gate structure on a top surfaces and sidewalls of the first ends of the first plurality of fins; and

a second dummy gate structure on a top surfaces and sidewalls of second ends of the first plurality of fins, the second ends being opposite the first ends; and

gate spacers on sidewalls of the first and second dummy gate structures.

12. The FinFET device of claim 11 , wherein the third width is from about 1.2 to about 5 times larger than the fourth width.

13. The FinFET device of claim 11 , wherein the first width is from about 1.2 to about 5 times larger than the second width.

14. The FinFET device of claim 11 further comprising:

a second plurality of fins extending above the substrate, the second plurality of fins being parallel to the first plurality of fins;

a second source region on the second plurality of fins, the second source region having the first width; and

a second drain region on the second plurality of fins, the second drain region having the second width.

15. The FinFET device of claim 14 further comprising:

a second source contact over and electrically coupled to the second source region, the second source contact having the third width; and

a second drain contact over and electrically coupled to the second drain region, the second drain contact having the fourth width.

16. The FinFET device of claim 14 further comprising:

a first gate over the first plurality of fins, wherein the first gate is interposed between the first source region and the first drain region; and

a second gate over the second plurality of fins, wherein the second gate is interposed between the second source region and the second drain region.

17. The FinFET device of claim 11 further comprising:

a first gate over the first plurality of fins, wherein the first gate is interposed between the first source region and the first drain region;

a second source region on the first plurality of fins, the second source region having the first width;

a second gate over the first plurality of fins, wherein the second gate is interposed between the first drain region and the second source region;

a second drain region on the first plurality of fins, the second drain region having the second width;

a third gate over the first plurality of fins, wherein the third gate is interposed between the second source region and the second drain region;

a third source region on the first plurality of fins, the third source region having the first width; and

a fourth gate over the first plurality of fins, wherein the fourth gate is interposed between the second drain region and the third source region.

18. A method for forming a FinFET device, the method comprising:

forming a first semiconductor fin over a substrate;

doping the first semiconductor fin with dopants of a first conductivity type;

forming a first source region on the first semiconductor fin, the first source region having a first width;

forming a first drain region on the first semiconductor fin, the first drain region having a second width, the second width being smaller than the first width;

forming a first gate over the first semiconductor fin, the first active gate being laterally between the first source region and the first drain region, a doped portion of the first semiconductor fin below the first active gate between the first source region and the first drain region forming a first channel region;

forming a first dummy gate over a first end of the first semiconductor fin, the first dummy gate being adjacent the first source region; and

forming a second dummy gate over a second end of the first semiconductor fin, the second dummy gate being adjacent the first drain region, the second end of the first semiconductor fin being opposite the first end.

19. The method of claim 18 , wherein the forming the first source region further comprises epitaxially growing the first source region on the first semiconductor fin, and wherein the forming the first drain region further comprises epitaxially growing the first drain region on the first semiconductor fin.

20. The method of claim 18 further comprising:

forming a first source contact over and in electrical contact with the first source region, the first source contact having a third width; and

forming a first drain contact over and in electrical contact with the first drain region, the first drain contact having a fourth width, wherein the third width is from about 1.2 to about 5 times larger than the fourth width.

21. The method of claim 18 , wherein:

the forming the first source region on the first semiconductor fin further comprises:

etching a first recess in the first semiconductor fin; and

epitaxially growing a first semiconductor material in the first recess;

the forming the first drain region on the first semiconductor fin further comprises:

etching a second recess in the first semiconductor fin; and

epitaxially growing a second semiconductor material in the second recess.