Semiconductor device and fabrication method for the same
The semiconductor device includes: a transistor having a gate electrode formed on a semiconductor substrate and first and second source/drain regions formed in portions of the semiconductor substrate on both sides of the gate electrode; a gate interconnect formed at a position opposite to the gate electrode with respect to the first source/drain region; and a first silicon-germanium layer formed on the first source/drain region to protrude above the top surface of the semiconductor substrate. The gate interconnect and the first source/drain region are connected via a local interconnect structure that includes the first silicon-germanium layer.
1. A semiconductor device comprising:
a gate electrode formed on an active region of a substrate;
a first silicon-germanium layer formed in a first recess provided in a portion of the active region on a first side of the gate electrode;
a first silicide layer formed on the first silicon-germanium layer;
a gate interconnect formed on a region of the active region opposite side of the gate electrode to the first silicon-germanium layer;
a second silicide layer formed on the gate interconnect;
a first contact plug connected to the first and second silicide layer;
a first side wall formed on one side surface of the first gate interconnected closer to the first silicon-germanium layer; and
a second side wall formed on another side surface of the gate interconnect opposite to the first silicon-germanium layer, wherein:
the first contact plug is a shared contact plug to connect the first silicon-germanium layer and the gate interconnect, and
a top position of a part of the first side wall which is located under first contact plug is lower than a top position of the second side wall.
2. The semiconductor device of claim 1 , wherein the first contact plug is connected only to a part of the second silicide layer closer to the first silicon-germanium layer in the gate length direction.
3. The semiconductor device of claim 1 , wherein the second silicide layer is thinner than the gate interconnect.
4. The semiconductor device of claim 1 , wherein each of the first and second silicide layer is made of a silicide containing nickel.
5. The semiconductor device of claim 1 , wherein each of the gate electrode and the gate interconnect is made of a polysilicon.
6. The semiconductor device of claim 1 , wherein the first contact plug is made of a material containing tungsten.
7. The semiconductor device of claim 1 , wherein the first silicon-germanium layer is projected from an upper surface of the substrate.
8. The semiconductor device of claim 1 , wherein
the gate electrode is formed on the active region via a gate insulating film,
the gate interconnect is formed on the active region via a insulating film, and
the gate insulating film and the insulating film are made of the same insulating material and have the same thickness.
9. The semiconductor device of claim 1 , wherein the first silicon-germanium layer is a epitaxial layer.
10. The semiconductor device of claim 1 , wherein the first contact plug does not contact with the second side wall.
11. The semiconductor device of claim 1 , wherein the second side wall includes an inner side wall having an L-shaped cross section and an outer side wall formed on the inner side wall.
12. The semiconductor device of claim 1 , wherein a part of a side surface of the gate interconnect which is located under the first contact is not covered by the side wall.
13. The semiconductor device of claim 1 , wherein the first contact plug connected to a side surface of the gate interconnect which is located under the first contact plug.
14. The semiconductor device of claim 1 , further comprising:
a third silicide layer formed on the gate electrode, wherein
the third silicide layer is thinner than the gate electrode.
15. The semiconductor device of claim 1 , further comprising:
a second silicon-germanium layer formed in a second recess provided in a portion of the active region on a second side of the gate electrode; and
a fourth silicide layer formed on the second silicon-germanium layer.
16. The semiconductor device of claim 15 , further comprising:
the second contact plug connected to the fourth silicide layer, wherein
the first contact plug is larger than the second contact plug.
17. The semiconductor device of claim 1 , further comprising:
an underlying insulating film formed on the gate electrode; and
an interlayer insulating film formed on the underlying insulating film, wherein
the interlayer insulating film has a flat top surface, and
the first contact plug is formed to penetrate the interlayer insulating film and the underlying insulating film.
18. The semiconductor device of claim 17 , wherein the underlying insulating film is made of silicon nitride.