Semiconductor device including active pattern having a protrusion portion on a base portion and method for manufacturing the same
A semiconductor device including an active pattern, which has a base portion and a protrusion portion on the base portion, and a source/drain pattern provided on the base portion may be provided. The protrusion portion may include a first curved pattern portion, a first flat pattern portion disposed at a lower level than the first curved pattern portion, and a second curved pattern portion disposed at a lower level than the first flat pattern portion. Each of the first and second curved pattern portions has a curved side wall, and the first flat pattern portion has a flat side wall. The germanium concentration of the first curved pattern portion is a higher than the germanium concentration of the first flat pattern portion, and the germanium concentration of the first flat pattern portion is higher than the germanium concentration of the second curved pattern portion.
1. A semiconductor device comprising:
an active pattern comprising a base portion and a protrusion portion on the base portion; and
a source/drain pattern on the base portion,
wherein the protrusion portion comprises a first curved pattern portion, a first flat pattern portion, and a second curved pattern portion, the first flat pattern portion being at a lower level than the first curved pattern portion, the second curved pattern portion being at a lower level than the first flat pattern portion,
wherein each of the first and second curved pattern portions has a curved side wall,
wherein the first flat pattern portion has a flat side wall,
wherein a germanium concentration of the first curved pattern portion is a higher than a germanium concentration of the first flat pattern portion, and
wherein the germanium concentration of the first flat pattern portion is higher than a germanium concentration of the second curved pattern portion.
2. The semiconductor device according to claim 1 , wherein a level of a boundary between the base portion and the protrusion portion may be equal to a level of a bottom surface of the source/drain pattern.
3. The semiconductor device according to claim 1 , wherein the base portion has a flat side wall.
4. The semiconductor device according to claim 1 , wherein:
the protrusion portion further comprises a second flat pattern portion being at a lower level than the second curved pattern portion; and
the germanium concentration of the second curved pattern portion is higher than a germanium concentration of the second flat pattern portion.
5. The semiconductor device according to claim 4 , wherein a minimum width of the second curved pattern portion is smaller than a minimum width of the first flat pattern portion, and is smaller than a minimum width of the second flat pattern portion.
6. The semiconductor device according to claim 1 , wherein the first curved pattern portion is an uppermost portion of the active pattern.
7. The semiconductor device according to claim 1 , wherein:
the protrusion portion comprises a plurality of protrusion portions; and
the source/drain pattern is provided among an adjacent pair of the plurality of protrusion portions.
8. A semiconductor device comprising:
an active pattern comprising a base portion and a protrusion portion on the base portion; and
a source/drain pattern on the base portion,
wherein the protrusion portion comprises a first flat pattern portion and a first curved pattern portion being at a lower level than the first flat pattern portion, a second flat pattern portion being at a lower level than the first curved pattern portion
wherein a minimum width of the first flat pattern portion is greater than a minimum width of the first curved pattern portion,
wherein a germanium concentration of the first flat pattern portion is higher than a germanium concentration of the first curved pattern portion, and
wherein the germanium concentration of the first curved pattern portion is higher than a germanium concentration of the second flat pattern portion.
9. The semiconductor device according to claim 8 , wherein:
a level of a boundary between the base portion and the protrusion portion is equal to a level of a bottom surface of the source/drain pattern; and
a side wall of the base portion is flat.
10. The semiconductor device according to claim 8 , wherein a germanium concentration of the base portion is lower than the germanium concentration of the first curved pattern portion.
11. The semiconductor device according to claim 8 , wherein:
the protrusion portion further comprises a second curved pattern portion being at a lower level than the second flat pattern portion; and
the germanium concentration of the second flat pattern portion is higher than a germanium concentration of the second curved pattern portion.
12. The semiconductor device according to claim 11 , wherein a minimum width of the second flat pattern portion is greater than the minimum width of the first curved pattern portion and a minimum width of the second curved pattern portion.
13. The semiconductor device according to claim 8 , wherein a germanium concentration of the protrusion portion decreases continuously as the protrusion portion extends toward the base portion.
14. The semiconductor device according to claim 8 , further comprising:
a gate insulating layer covering the protrusion portion,
wherein the gate insulating layer comprises a portion curved corresponding to a side wall of the first curved pattern portion.
15. A semiconductor device comprising:
an active pattern comprising a base portion and a protrusion portion on the base portion;
a source/drain pattern on the base portion; and
a gate structure on the protrusion portion,
wherein a level of a boundary between the base portion and the protrusion portion is equal to a level of a bottom surface of the source/drain pattern,
wherein the protrusion portion comprises a first flat pattern portion and a first curved pattern portion being at a lower level than the first flat pattern portion,
wherein a side wall of the first flat pattern portion is flat,
wherein a side wall of the first curved pattern portion is curved,
wherein a minimum width of the first flat pattern portion is greater than a minimum width of the first curved pattern portion,
wherein a germanium concentration of the first flat pattern portion is higher than a germanium concentration of the first curved pattern portion, and
wherein the germanium concentration of the first curved pattern portion is higher than a germanium concentration of the base portion.
16. The semiconductor device according to claim 15 , wherein:
the protrusion portion further comprises a second flat pattern portion being at a lower level than the first curved pattern portion; and
the germanium concentration of the first curved pattern portion is higher than a germanium concentration of the second flat pattern portion.
17. The semiconductor device according to claim 15 , wherein:
the base portion comprises a flat base portion and a curved base portion being at a lower level than the flat base portion;
a side wall of the flat base portion is flat; and
a side wall of the curved base portion is curved.
18. The semiconductor device according to claim 17 , wherein a germanium concentration of the flat base portion is higher than a germanium concentration of the curved base portion.
19. The semiconductor device according to claim 17 , further comprising:
an insulating spacer covering the side wall of the flat base portion and the side wall of the curved base portion,
wherein a portion of the insulating spacer covering the side wall of the curved base portion is curved.
20. The semiconductor device according to claim 15 , wherein a width of the first curved pattern portion increases gradually as the first curved pattern portion extends toward the first flat pattern portion.