Epitaxial source/drain and methods of forming same

1. A method, comprising:

providing a substrate including a plurality of fins extending from the substrate;

forming a liner layer over the plurality of fins;

patterning the liner layer to form a patterned liner layer that exposes a first group of fins of the plurality of fins in a first region;

forming a first epitaxial layer over the exposed first group of fins and forming a barrier layer over the first epitaxial layer;

removing the patterned liner layer; and

selectively forming a second epitaxial layer over a second group of fins of the plurality of fins in a second region, wherein a hybrid fin interposes adjacent fins in the second region.

2. The method of claim 1 , further comprising:

prior to forming the liner layer, forming a trench within an isolation region interposing the adjacent fins in the second region; and

filling the trench with an isolation material to form the hybrid fin interposing the adjacent fins in the second region;

wherein the hybrid fin is configured to prevent lateral merging of the second epitaxial layer selectively formed over the adjacent fins in the second region.

3. The method of claim 1 , wherein the first region includes an N-type region, wherein the second region includes a P-type region, and wherein the first epitaxial layer includes an epitaxial N-type source/drain structure.

4. The method of claim 1 , wherein the barrier layer includes a phosphorus doped SiP layer.

5. The method of claim 4 , wherein the phosphorus doped SiP layer has a phosphorus doping concentration greater than or equal to about 1.03×10 22 atoms/cm 3 .

6. The method of claim 1 , wherein the liner layer includes an oxide layer.

7. The method of claim 1 , wherein the liner layer has a thickness of about 6-10 nm.

8. The method of claim 1 , wherein the first region includes an N-type region, wherein the second region includes a P-type region, and wherein the second epitaxial layer includes an epitaxial P-type source/drain structure.

9. The method of claim 1 , wherein the second epitaxial layer includes a SiGe layer, a Ge layer, a boron doped SiGe layer (SiGe:B), or a combination thereof.

10. The method of claim 1 , wherein the barrier layer prevents growth of the second epitaxial layer over the first group of fins.

11. The method of claim 1 , further comprising:

after selectively forming the second epitaxial layer, removing the barrier layer.

12. A method of fabricating a semiconductor device, comprising:

forming a first group of fins in an N-type region, a second group of fins in a P-type region, a first hybrid fin interposing adjacent fins of the second group of fins, and a second hybrid fin at a boundary between the N-type region and the P-type region;

forming a patterned dielectric isolation layer over the second group of fins, the first hybrid fin, and at least partially over the second hybrid fin;

growing an epitaxial N-type source/drain structure over the first group of fins in the N-type region and forming a barrier layer over the epitaxial N-type source/drain structure;

removing the patterned dielectric isolation layer; and

selectively growing an epitaxial P-type source/drain structure over the second group of fins in the P-type region.

13. The method of claim 12 , wherein the forming the patterned dielectric isolation layer further comprises:

depositing a dielectric isolation layer over the first group of fins, the second group of fins, the first hybrid fin, and the second hybrid fin; and

performing a photolithography and etch process to remove the dielectric isolation layer from the N-type region to form the patterned dielectric isolation layer.

14. The method of claim 12 , further comprising:

after selectively growing the epitaxial P-type source/drain structure over the second group of fins in the P-type region, removing the barrier layer.

15. The method of claim 14 , wherein the removing the barrier layer also removes a portion of a first isolation region in the N-type region underlying the epitaxial N-type source/drain structure.

16. The method of claim 14 , wherein the removing the barrier layer also etches a portion of the epitaxial N-type source/drain structure.

17. The method of claim 15 , wherein the removing the portion of the first isolation region in the N-type region causes the first isolation region in the N-type region to be disposed at a lower height than a second isolation region in the P-type region.

18. The method of claim 12 , wherein the first hybrid fin is configured to prevent lateral merging of the epitaxial P-type source/drain structure selectively formed over the adjacent fins of the second group of fins.

19. A method, comprising:

forming a first recessed fin, a second recessed fin, and a hybrid fin interposing the first recessed fin and the second recessed fin;

forming a patterned liner layer that covers at least the second recessed fin;

after forming the patterned liner layer, forming a first epitaxial feature over the first recessed fin and a barrier layer over the first epitaxial feature; and

after removing the patterned liner layer, forming a second epitaxial feature over the second recessed fin while the barrier layer prevents formation of the second epitaxial feature over the first epitaxial feature.

20. The method of claim 19 , further comprising:

after forming the second epitaxial feature, removing the barrier layer and etching an isolation region underlying the first epitaxial feature.