Semiconductor device having germanium containing active pattern and method for fabricating the same

1. A semiconductor device, comprising:

a gate electrode extending in a first direction on a substrate;

a first active pattern extending in a second direction intersecting the first direction on the substrate to penetrate the gate electrode, the first active pattern including germanium;

an epitaxial pattern on a side wall of the gate electrode;

a first semiconductor oxide layer between the first active pattern and the gate electrode, and including a first semiconductor material; and

a second semiconductor oxide layer between the gate electrode and the epitaxial pattern, and including a second semiconductor material,

wherein a concentration of germanium of the first semiconductor material is less than a concentration of germanium of the first active pattern, and

wherein the concentration of germanium of the first semiconductor material is different from a concentration of germanium of the second semiconductor material.

2. The semiconductor device as claimed in claim 1 , wherein the concentration of germanium of the second semiconductor material is less than a concentration of germanium of the epitaxial pattern.

3. The semiconductor device as claimed in claim 2 , wherein the epitaxial pattern includes silicon germanium.

4. The semiconductor device as claimed in claim 1 , wherein the concentration of germanium of the first semiconductor material is less than the concentration of germanium of the second semiconductor material.

5. The semiconductor device as claimed in claim 1 , wherein a concentration of silicon of the first semiconductor material is greater than a concentration of silicon of the first active pattern.

6. The semiconductor device as claimed in claim 1 , wherein a concentration of silicon of the second semiconductor material is greater than a concentration of silicon of the epitaxial pattern.

7. The semiconductor device as claimed in claim 1 , wherein the first semiconductor oxide layer extends along a profile of an outer surface of the first active pattern.

8. The semiconductor device as claimed in claim 1 , further comprising:

a second active pattern extending in the second direction above the first active pattern and penetrating the gate electrode, the second active pattern including germanium; and

a second semiconductor oxide layer between the second active pattern and the gate electrode, the second semiconductor oxide layer including a third semiconductor material,

wherein a concentration of germanium of the third semiconductor material is less than the concentration of germanium of the second active pattern, and

wherein the concentration of germanium of the third semiconductor material is different from the concentration of germanium of the second semiconductor material.

9. The semiconductor device as claimed in claim 1 , further comprising:

a fin-shaped protrusion protruding from an upper surface of the substrate and extending in the second direction; and

a third semiconductor oxide layer between the fin-shaped protrusion and the gate electrode and including a third semiconductor material,

wherein a concentration of germanium of the third semiconductor material is less than a concentration of germanium of the fin-shaped protrusion.

10. The semiconductor device as claimed in claim 9 , further comprising:

a field insulating layer surrounding at least a part of side walls of the fin-shaped protrusion,

wherein the third semiconductor oxide layer extends along a profile of an outer surface of the fin-shaped protrusion exposed by the field insulating layer.

11. A semiconductor device comprising:

a first active pattern disposed above and spaced apart from a substrate, the first active pattern including germanium;

a first gate electrode between the substrate and the first active pattern;

a first epitaxial pattern disposed on side walls of the first active pattern and side walls of the first gate electrode;

a first semiconductor oxide layer between the first active pattern and the first gate electrode, and including a first semiconductor material; and

a second semiconductor oxide layer between the first gate electrode and the first epitaxial pattern, and including a second semiconductor material,

wherein a concentration of germanium of the first semiconductor material is less than a concentration of germanium of the first active pattern, and

wherein the concentration of germanium of the first semiconductor material is different from a concentration of germanium of the second semiconductor material.

12. The semiconductor device as claimed in claim 11 , further comprising:

gate spacers on the substrate that define two side walls of the first gate electrode,

wherein at least a portion of the first semiconductor oxide layer is buried in the first active pattern between the gate spacers.

13. The semiconductor device as claimed in claim 11 , further comprising:

a gate insulating layer extending along an outer surface of the first gate electrode and in contact with the first semiconductor oxide layer and the second semiconductor oxide layer.

14. The semiconductor device as claimed in claim 11 , further comprising:

a third semiconductor oxide layer between the substrate and the first gate electrode, and including a third semiconductor material,

wherein a concentration of germanium of the third semiconductor material is less than a concentration of germanium of the substrate.

15. The semiconductor device as claimed in claim 14 , wherein at least a part of the third semiconductor oxide layer is buried in the substrate.

16. The semiconductor device as claimed in claim 11 , wherein at least a part of the second semiconductor oxide layer is buried in the first epitaxial pattern.

17. The semiconductor device as claimed in claim 11 , further comprising:

a second active pattern disposed above and spaced apart from the substrate, and including a third semiconductor material;

a second gate electrode between the substrate and the second active pattern; and

a third semiconductor oxide layer between the second active pattern and the second gate electrode, and including a third semiconductor material,

wherein a concentration of germanium of the third semiconductor material is greater than a concentration of germanium of the second active pattern.

18. A semiconductor device comprising:

a gate electrode extending in a first direction on a substrate;

an active pattern extending in a second direction intersecting the first direction on the substrate to penetrate the gate electrode, the active pattern including silicon germanium;

an epitaxial pattern on a side wall of the gate electrode, the epitaxial pattern including silicon germanium, a concentration of germanium in the epitaxial pattern being different from a concentration of germanium in the active pattern;

a first semiconductor oxide layer between the active pattern and the gate electrode and including an oxide of silicon and germanium; and

a second semiconductor oxide layer between the gate electrode and the epitaxial pattern and including an oxide of silicon and germanium, a concentration of germanium in the second semiconductor oxide layer being different from a concentration of germanium in the first semiconductor oxide layer.

19. The semiconductor device as claimed in claim 18 , wherein the active pattern is treated to remove germanium from a surface thereof such that a concentration of germanium of the active pattern increases away from a surface that contacts the first semiconductor oxide layer.

20. The semiconductor device as claimed in claim 18 , wherein the active pattern comprises a first semiconductor layer, and a second semiconductor layer between the first semiconductor layer and the first semiconductor oxide layer,

wherein the first semiconductor layer includes germanium, and

wherein the second semiconductor layer includes silicon germanium.