Semiconductor device with a contact plug adjacent a gate structure

1. A semiconductor device comprising:

a substrate;

a gate structure on the substrate, wherein the gate structure comprises a gate electrode;

a source/drain layer on the substrate adjacent the gate structure;

a first etch stop layer, a second etch stop layer, and interlayer insulation layer that are stacked on an upper surface of the gate electrode that is opposite the substrate; and

a contact plug penetrating the interlayer insulation layer, the second etch stop layer, and the first etch stop layer,

wherein the contact plug contacts a sidewall of the gate structure,

wherein the contact plug comprises a lower portion having a first width and an upper portion having a second width that is greater than the first width,

wherein the contact plug comprises a barrier pattern that extends on first and second side surfaces of the contact plug and on a lower surface of the contact plug, the lower surface of the contact plug is lower than the first side surface of the contact plug,

wherein the barrier pattern contacts the interlayer insulation layer, the second etch stop layer, and the first etch stop layer,

wherein a first portion of the lower surface of the contact plug directly adjacent the first side surface has a first stepped shape and the second side surface of the contact plug comprises a second stepped shape,

wherein a second portion of the lower surface of the contact plug directly adjacent the second side surface is substantially flat, and

wherein a portion of an upper surface of the source/drain layer under the first stepped shape of the lower surface of the contact plug protrudes upwardly from other portions of the upper surface of the source/drain layer.

2. The device of claim 1 ,

wherein the contact plug comprises a first sidewall and a second sidewall that is opposite the first sidewall,

wherein the lower portion of the contact plug is positioned below a height level of an upper surface of the gate structure,

wherein the upper portion of the contact plug is positioned equal to or above the height level of the upper surface of the gate structure, and

wherein the first sidewall of the contact plug is bent at the height level of the upper surface of the gate structure.

3. The device of claim 2 , wherein the second sidewall of the contact plug has a constant slope with respect to an upper surface of the substrate.

4. The device of claim 1 ,

wherein the contact plug comprises a first sidewall and a second sidewall that is opposite the first sidewall,

wherein the lower portion of the contact plug is positioned below a height level of an upper surface of the gate structure,

wherein the upper portion of the contact plug is positioned equal to or above the height level of the upper surface of the gate structure,

wherein the first sidewall of the contact plug comprises a sloped portion with respect to an upper surface of the substrate, and

wherein the sloped portion is below the height level of the upper surface of the gate structure.

5. The device of claim 1 , wherein the first and second etch stop layers comprise different materials.

6. The device of claim 1 , wherein the gate structure comprises:

a gate insulation pattern on a sidewall of the gate electrode and a lower surface of the gate electrode;

a gate spacer on a sidewall of the gate insulation pattern; and

a capping pattern on the gate electrode, the gate insulation pattern, and the gate spacer.

7. The device of claim 6 , wherein a lower surface of the capping pattern is curved.

8. The device of claim 6 , wherein a portion of an upper surface of the capping pattern contacts a lower sidewall of the upper portion of the contact plug.

9. The device of claim 1 , further comprising:

a source/drain layer on the substrate adjacent to the gate structure,

wherein the contact plug vertically overlaps the source/drain layer.

10. The device of claim 9 , further comprising:

a metal silicide pattern between an upper surface of the source/drain layer and the lower surface of the contact plug,

wherein an upper surface of the metal silicide pattern has a shape corresponding to a shape of the lower surface of the contact plug.

11. The device of claim 1 , wherein the gate structure comprises a plurality of gate structures spaced apart from each other in a first direction parallel to an upper surface of the substrate, and

wherein the contact plug contacts facing sidewalls of adjacent gate structures of ones of the plurality of the gate structures.

12. The device of claim 11 , further comprising:

a plurality of active fins on the substrate,

wherein each of the plurality of active fins extends in the first direction, and

wherein each of the plurality of gate structures is on the plurality of active fins and extends in a second direction crossing the first direction.

13. A semiconductor device comprising:

a substrate;

a gate structure on the substrate, wherein the gate structure comprises a gate electrode;

a first source/drain layer and a second source/drain layer on the substrate adjacent to a first sidewall of the gate structure and a second sidewall of the gate structure, respectively;

a first interlayer insulation layer on the substrate and the first and second source/drain layers;

a first etch stop layer, a second etch stop layer, and a second interlayer insulation layer that are sequentially stacked on an upper surface of the gate electrode that is opposite the substrate and the first interlayer insulation layer; and

a first contact plug and a second contact plug on the first source/drain layer and the second source/drain layer, respectively, and penetrating the second interlayer insulation layer, the second etch stop layer, the first etch stop layer, and the first interlayer insulation layer,

wherein the first contact plug directly contacts the first sidewall of the gate structure and a portion of an upper surface of the gate structure adjacent to the first sidewall of the gate structure,

wherein the second contact plug is spaced apart from the second sidewall of the gate structure by the first interlayer insulation layer,

wherein the second contact plug includes a side surface and a lower surface that is lower than the side surface,

wherein a portion of the lower surface of the second contact plug directly adjacent the gate structure has a first stepped shape,

wherein a side surface of the first contact plug directly adjacent the gate structure comprises a second stepped shape that is spaced apart from a lower surface of the first contact plug,

wherein a portion of the lower surface of the first contact plug directly adjacent the first sidewall of the gate structure is substantially flat, and

wherein a portion of an upper surface of the second source/drain layer under the first stepped shape of the lower surface of the second contact plug protrudes upwardly from other portions of the upper surface of the source/drain layer.

14. The device of claim 13 ,

wherein the first contact plug comprises a lower portion having a first width and an upper portion having a second width greater than the first width,

wherein a lower sidewall of the upper portion of the first contact plug contacts the portion of the upper surface of the gate structure, and

wherein the first contact plug has a lower surface having a stepped shape.

15. The device of claim 13 ,

wherein the first source/drain layer and the second source/drain layer are merged together, and

wherein the first interlayer insulation layer does not completely fill a space between the first source/drain layer and the second source/drain layer that are merged together and a device isolation pattern.

16. The device of claim 13 , further comprising:

a first metal silicide pattern between the first source/drain layer and the first contact plug; and

a second metal silicide pattern between the second source/drain layer and the second contact plug,

wherein the first metal silicide pattern has an upper surface having a stepped shape, and

wherein the second metal silicide pattern is between the second source/drain layer and the first interlayer insulation layer adjacent to the second contact plug.

17. The device of claim 13 , wherein the gate structure comprises:

a gate electrode;

a gate insulation pattern on a sidewall of the gate electrode and a lower surface of the gate electrode;

a gate spacer on a sidewall of the gate insulation pattern; and

a capping pattern on the gate electrode, the gate insulation pattern, and the gate spacer,

wherein a lower surface of the capping pattern is curved.

18. A semiconductor device comprising:

a substrate;

a first gate structure and a second gate structure on the substrate, wherein each of the first gate structure and the second gate structure comprises:

a gate electrode;

a gate insulation pattern on a sidewall of the gate electrode and a lower surface of the gate electrode;

a gate spacer on a sidewall of the gate insulation pattern; and

a capping pattern on the gate electrode, the gate insulation pattern, and the gate spacer;

a source/drain layer on the substrate between the first gate structure and the second gate structure;

a first etch stop layer on the capping pattern; and

a contact plug on the source/drain layer,

wherein the contact plug contacts a sidewall of the gate spacer of the first gate structure, a sidewall and a portion of an upper surface of the capping pattern of the first gate structure, a sidewall of the gate spacer of the second gate structure, and a sidewall of the capping pattern of the second gate structure,

wherein the contact plug includes a lower portion having a first width and an upper portion having a second width that is greater than the first width, the contact plug includes first and second side surfaces and a lower surface that is lower than the first side surface and a portion of the lower surface of the lower portion of the contact plug has a first stepped shape directly adjacent the first side surface of the contact plug and at a height lower than that of a lower surface of the capping pattern,

wherein the second side surface of the contact plug has a second stepped shape at an interface between the lower portion having the first width and the upper portion having the second width,

wherein the second stepped shape is at a same height as a lower surface of the first etch stop layer and is higher than the first stepped shape, relative to the substrate,

wherein a portion of the lower surface of the lower portion of the contact plug directly adjacent the second side surface of the contact plug is substantially flat, and

wherein a portion of an upper surface of the source/drain layer under the first stepped shape of the lower surface of the lower portion of the contact plug protrudes upwardly from other portions of the upper surface of the source/drain layer.

19. The device of claim 18 , further comprising:

a second etch stop layer and an interlayer insulation layer that are sequentially stacked on the first gate structure and the second gate structure,

wherein the contact plug penetrates the interlayer insulation layer, the second etch stop layer, and the first etch stop layer.

20. The device of claim 19 ,

wherein the gate spacer, the capping pattern, and the second etch stop layer comprise nitride, and

wherein the first etch stop layer and the interlayer insulation layer comprise oxide.