Semiconductor device having cap layer
A semiconductor device includes a semiconductive substrate, a semiconductive fin, an isolation structure, a source/drain epitaxial structure, a first cap layer, and a second cap layer. The semiconductive fin protrudes from the semiconductive substrate. The isolation structure is over the semiconductive substrate and laterally surrounds the semiconductive fin. The source/drain epitaxial structure is over the semiconductive fin. The source/drain epitaxial structure has a rounded corner extending laterally and a top above the rounded corner. The first cap layer extends from the rounded corner of the source/drain epitaxial structure to the top of the source/drain epitaxial structure. The second cap layer covers the rounded corner and a bottom of the source/drain epitaxial structure. The first and second cap layers are made of different materials.
1. A semiconductor device comprising:
a semiconductive substrate;
a semiconductive fin protruding from the semiconductive substrate;
an isolation structure over the semiconductive substrate and laterally surrounding the semiconductive fin;
a source/drain epitaxial structure over the semiconductive fin, wherein the source/drain epitaxial structure has a rounded corner extending laterally and a top above the rounded corner;
a first cap layer extending from the rounded corner of the source/drain epitaxial structure to the top of the source/drain epitaxial structure;
a second cap layer covering the rounded corner and a bottom of the source/drain epitaxial structure, wherein the first and second cap layers are made of different materials; and
a contact over the second cap layer, wherein the first cap layer is a single piece of continuous material and in contact with the source/drain epitaxial structure, and the contact is in contact with a top surface of the first cap layer.
2. The semiconductor device of claim 1 , wherein the first cap layer comprises silicon.
3. The semiconductor device of claim 1 , wherein the second cap layer comprises silicon.
4. The semiconductor device of claim 1 , wherein the first cap layer and the second cap layer comprise different metals.
5. The semiconductor device of claim 1 , wherein the second cap layer is spaced apart from the top of the source/drain epitaxial structure.
6. The semiconductor device of claim 1 , wherein a bottommost surface of the source/drain epitaxial structure is lower than a bottommost surface of the second cap layer.
7. The semiconductor device of claim 1 , wherein the first cap layer comprises Ni, Co, Pt, W, Ru, or combinations thereof.
8. The semiconductor device of claim 1 , wherein the second cap layer comprises Ti, Er, Y, Yb, Eu, Tb, Lu, Th, Sc, Hf, Zr, Tb, Ta, or combinations thereof.
9. A semiconductor device comprising:
an isolation structure over a substrate;
a fin structure extending from the substrate and laterally surrounded by the isolation structure;
a source/drain epitaxial structure over the fin structure, wherein the source/drain epitaxial structure comprises a round corner directly above the isolation structure and a bottom under the round corner;
a first cap layer in contact with the round corner and the bottom of the source/drain epitaxial structure, wherein a topmost surface of the first cap layer is lower than a topmost surface of the source/drain epitaxial structure; and
a contact etch stop layer (CESL) covering the first cap layer.
10. The semiconductor device of claim 9 , wherein the first cap layer is a metal alloy layer.
11. The semiconductor device of claim 9 , further comprising a second cap layer over the source/drain epitaxial structure and in contact with the first cap layer.
12. The semiconductor device of claim 11 , wherein the second cap layer is a metal alloy layer.
13. The semiconductor device of claim 11 , wherein the CESL is in contact with the second cap layer.
14. The semiconductor device of claim 11 , wherein the first and second cap layers both comprise Si.
15. A semiconductor device comprising:
a substrate;
a fin structure protruding from the substrate;
an isolation structure laterally surrounding the fin structure;
a source/drain epitaxial structure over the fin structure;
a first cap layer in contact with a bottom of the source/drain epitaxial structure and spaced apart from the isolation structure;
a contact etch stop layer (CESL) in contact with the first cap layer and a top surface of the isolation structure; and
a contact covering and electrically connected to the source/drain epitaxial structure, wherein a bottommost surface of the contact is higher than a topmost surface of the first cap layer.
16. The semiconductor device of claim 15 , wherein the first cap layer comprises metals.
17. The semiconductor device of claim 15 , wherein a bottommost surface of the source/drain epitaxial structure is lower than the top surface of the isolation structure.
18. The semiconductor device of claim 15 , wherein the source/drain epitaxial structure has a rounded top.
19. The semiconductor device of claim 15 , wherein the source/drain epitaxial structure has a rounded corner directly above the isolation structure, and the first cap layer is in contact with the rounded corner of the source/drain epitaxial structure.
20. The semiconductor device of claim 15 , further comprising a second cap layer over and in contact with the source/drain epitaxial structure and the first cap layer, wherein the second cap layer comprises silicon.