Semiconductor device

1. A semiconductor device, comprising:

a first MIS transistor, wherein:

the first MIS transistor includes:

a first gate insulating film formed on a first active region in a semiconductor substrate,

a first gate electrode formed on the first gate insulating film,

a first sidewall spacer formed on a side surface of the first gate electrode,

a first source/drain region of a first conductivity type which is formed in a trench provided in the first active region on a lateral side of the first sidewall spacer, and which includes a silicon compound layer causing a first stress in a gate length direction of a channel region in the first active region, and

a stress insulating film which is formed on the first active region to cover the first gate electrode, the first sidewall spacer, and the first source/drain region, and which causes a second stress opposite to the first stress,

an uppermost surface of the silicon compound layer is located higher than a surface of the semiconductor substrate located directly under the first gate electrode,

a first stress-relief film is formed in a space between the silicon compound layer and the first sidewall spacer,

the first stress-relief film is formed on the side surface of the first gate electrode with the first sidewall spacer interposed therebetween, and

the first stress-relief film is not in direct contact with the side surface of the first gate electrode.

2. The semiconductor device of claim 1 , further comprising:

a first offset spacer which is formed between the first gate electrode and the first sidewall spacer, and whose cross-section has an I shape.

3. The semiconductor device of claim 1 , further comprising:

a first silicide layer formed on the first gate electrode; and

a second silicide layer formed on the first source/drain region which includes the silicon compound layer.

4. The semiconductor device of claim 1 , wherein the first stress-relief film is formed on a side surface of the silicon compound layer.

5. The semiconductor device of claim 1 , wherein the first sidewall spacer includes an inner sidewall spacer which is formed on the side surface of the first gate electrode, and whose cross-section has an L shape, and an outer sidewall spacer formed on the inner sidewall spacer.

6. The semiconductor device of claim 1 , wherein

the first sidewall spacer includes an inner sidewall spacer whose cross-section has an L shape, and

the stress insulating film is formed in contact with a surface of the inner sidewall spacer which is curved to have an L-shaped cross-section.

7. The semiconductor device of claim 1 , wherein

the first MIS transistor is a p-type MIS transistor,

the first stress is a compressive stress, and

the second stress is a tensile stress.

8. The semiconductor device of claim 1 , wherein

the silicon compound layer is a SiGe layer,

the stress insulating film is a silicon nitride film, and

the first stress-relief film is a silicon oxide film.

9. The semiconductor device of claim 1 , wherein

the first MIS transistor is an n-type MIS transistor,

the first stress is a tensile stress, and

the second stress is a compressive stress.

10. The semiconductor device of claim 1 , further comprising:

an isolation region formed in the semiconductor substrate to surround the first active region;

a gate interconnect formed on the isolation region;

an interconnect sidewall spacer formed on a side surface of the gate interconnect;

a second stress-relief film formed on a side surface of a recessed portion provided in the isolation region on a lateral side of the interconnect sidewall spacer; and

the stress insulating film formed on the isolation region to cover the gate interconnect, the interconnect sidewall spacer, and the second stress-relief film.

11. The semiconductor device of claim 1 , further comprising:

a second MIS transistor, wherein:

the second MIS transistor includes:

a second gate insulating film formed on a second active region in the semiconductor substrate,

a second gate electrode formed on the second gate insulating film,

a second sidewall spacer formed on a side surface of the second gate electrode,

a second source/drain region of a second conductivity type which is formed in the second active region on a lateral side of the second sidewall spacer, and

the stress insulating film formed on the second active region to cover the second gate electrode, the second sidewall spacer, and the second source/drain region.

12. The semiconductor device of claim 11 , wherein no first stress-relief film is formed on the second active region.

13. The semiconductor device of claim 1 , further comprising:

a third MIS transistor, wherein:

the third MIS transistor includes:

a third gate insulating film formed on a third active region in the semiconductor substrate,

a third gate electrode formed on the third gate insulating film,

a third sidewall spacer formed on a side surface of the third gate electrode,

a third source/drain region of a first conductivity type which is formed in the third active region on a lateral side of the third sidewall spacer,

a protective film formed on the third active region to cover the third gate electrode, the third sidewall spacer, and the third source/drain region, and

the stress insulating film formed on the protective film.

14. The semiconductor device of claim 13 , wherein no silicide layer is formed on the third gate electrode and the third source/drain region.

15. The semiconductor device of claim 13 , wherein the first stress-relief film and the protective film are made of a same insulating material.