Semiconductor device

1. A semiconductor device comprising:

a substrate;

a fin structure on the substrate;

a gate structure on the fin structure;

a gate spacer on at least one side surface of the gate structure; and

a source/drain structure on the fin structure,

wherein a topmost portion of a bottom surface of the gate spacer is lower than a topmost portion of a top surface of the fin structure,

a topmost portion of a top surface of the source/drain structure is lower than the topmost portion of the top surface of the fin structure, and

a bottom surface of the gate structure contacts the topmost portion of the top surface of the fin structure.

2. The semiconductor device of claim 1 , wherein

the gate spacer comprises an inner side surface contacting the gate structure and an outer side surface opposite to the inner side surface, and

the source/drain structure comprises a portion such that a distance from the portion of the source/drain structure to the gate structure in a horizontal direction is smaller than a distance from the outer side surface of the gate spacer to the gate structure in the horizontal direction.

3. The semiconductor device of claim 1 , wherein

the topmost portion of the bottom surface of the gate spacer is higher than a bottommost portion of the top surface of the fin structure.

4. The semiconductor device of claim 1 , wherein the source/drain structure is doped with a p-type dopant.

5. The semiconductor device of claim 1 , wherein

the fin structure comprises a plurality of channels separated from each other in a vertical direction,

the topmost portion of the bottom surface of the gate spacer is lower than a topmost portion of a top surface of a topmost channel from among the plurality of channels, and

the topmost portion of the top surface of the source/drain structure is lower than the topmost portion of the top surface of the topmost channel.

6. A semiconductor device comprising:

a substrate comprising a first region and a second region;

a first fin structure on the first region;

a second fin structure on the second region;

a first gate structure on the first fin structure;

a second gate structure on the second fin structure;

a first gate spacer on at least one side surface of the first gate structure;

a second gate spacer on at least one side surface of the second gate structure;

a first source/drain structure on the first fin structure; and

a second source/drain structure on the second fin structure,

wherein a topmost portion of a bottom surface of the first gate spacer is lower than a topmost portion of a top surface of the first fin structure,

wherein a topmost portion of a top surface of the first source/drain structure is lower than the topmost portion of the top surface of the first fin structure,

a bottom surface of the first gate structure contacts the topmost portion of the top surface of the first fin structure, and

a bottom surface of the second gate structure contacts the topmost portion of the top surface of the second fin structure.

7. The semiconductor device of claim 6 , wherein

the first source/drain structure comprises a first source/drain layer and a first capping layer directly on the first source/drain layer, and

the second source/drain structure comprises a second source/drain layer, a third source/drain layer on the second source/drain layer, and a second capping layer on the third source/drain layer.

8. The semiconductor device of claim 7 , wherein a Si concentration of the first source/drain layer is lower than a Si concentration of the first capping layer, and

wherein a Si concentration of the second source/drain layer is lower than a Si concentration of the second capping layer.

9. The semiconductor device of claim 7 , wherein

a Si concentration of the third source/drain layer is lower than a Si concentration of the second source/drain layer.

10. The semiconductor device of claim 7 , wherein

the first source/drain layer and the second source/drain layer comprise a substantially same first composition, and

the first capping layer and the second capping layer comprise a substantially same second composition.

11. The semiconductor device of claim 7 , wherein

the first source/drain layer, the second source/drain layer, and the third source/drain layer comprise SiGe.

12. The semiconductor device of claim 7 , wherein

the first source/drain layer, the second source/drain layer, and the third source/drain layer comprise a p-type dopant.

13. The semiconductor device of claim 6 , wherein

a distance from the topmost portion of the top surface of the first fin structure to a bottommost portion of the top surface of the first fin structure in a vertical direction is less than a distance from a topmost portion of a top surface of the second fin structure to a bottommost portion of the top surface of the second fin structure in the vertical direction.

14. The semiconductor device of claim 6 , wherein

a topmost portion of a bottom surface of the second gate spacer is lower than a bottommost portion of a top surface of the second fin structure.

15. The semiconductor device of claim 6 , wherein

a height of a topmost portion of a bottom surface of the second gate spacer is greater than or equal to a height of a bottommost portion of a top surface of the second fin structure.

16. A semiconductor device comprising:

a substrate comprising a first region and a second region;

a plurality of first fin structures on the first region;

a plurality of second fin structures on the second region;

a plurality of first gate structures, each first gate structure from among the plurality of first gate structures being on a respective first fin structure from among the plurality of first fin structures;

a second gate structure on the plurality of second fin structures;

a plurality of first gate spacers, each first gate spacer from among the plurality of first gate spacers being on side surfaces of a respective first gate structure from among the plurality of first gate structures;

a second gate spacer on side surfaces of the second gate structure;

a plurality of first source/drain structures, each first source/drain structure being on a respective first fin structure from among the plurality of first fin structures; and

a second source/drain structure on the plurality of second fin structures,

wherein a topmost portion of a bottom surface of each first gate spacer from among the plurality of first gate spacers is lower than a topmost portion of a top surface of a respective first fin structure from among the plurality of first fin structures,

a topmost portion of a top surface of each first source/drain structure from among the plurality of first source/drain structures is lower than a topmost portion of a top surface of a respective first fin structure from among the plurality of first fin structures,

a bottom surface of each first gate structure from among the plurality of first gate structures contacts the topmost portion of the top surface of the respective first fin structure from among the plurality of first fin structures, and

a bottom surface of the second gate structure contacts the topmost portion of the top surfaces of the plurality of second fin structures.

17. The semiconductor device of claim 16 , wherein

the plurality of first source/drain structures are separated from one another, and

the second source/drain structure contacts all of the plurality of second fin structures.

18. The semiconductor device of claim 16 , wherein

a pitch between adjacent first fin structures from among the plurality of first fin structures is greater than a pitch between adjacent second fin structures from among the plurality of second fin structures.

19. The semiconductor device of claim 16 , wherein

a length of each first source/drain structure from among the plurality of first source/drain structures in a vertical direction is less than a length of the second source/drain structure in the vertical direction.

20. The semiconductor device of claim 16 , wherein

each first source/drain structure from among the plurality of first source/drain structures comprises a first predetermined number of layers, and

the second source/drain structure comprises a second predetermined number of layers, the second predetermined number being greater than the first predetermined number.