Semiconductor device

1. A semiconductor device including a first MIS transistor and a second MIS transistor, wherein

the first MIS transistor includes:

a first gate insulating film formed on a first active region of a semiconductor substrate and including a first high dielectric constant film,

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

first offset sidewalls formed on side surfaces in a gate length direction of the first gate electrode,

second offset sidewalls formed on side surfaces in a gate length direction and the side surfaces of the gate width direction of the first gate electrode with the first offset sidewalls being interposed between the second offset sidewalls and the first gate electrode, and

first extension regions formed in the first active region laterally outside the first gate electrode,

the second MIS transistor includes:

a second gate insulating film formed on a second active region of the semiconductor substrate and including a second high dielectric constant film,

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

third offset sidewalls formed on side surfaces in a gate length direction and a gate width direction of the second gate electrode,

fourth offset sidewalls formed on the side surfaces in the gate length and width directions of the second gate electrode with the third offset sidewalls being interposed between the fourth offset sidewalls and the second gate electrode, and

second extension regions formed in the second active region laterally outside the second gate electrode, and

the first offset sidewalls are formed along the gate length direction but not formed along the gate width direction of the first gate electrode.

2. The semiconductor device of claim 1 , wherein the second gate insulating film has a thickness greater than that of the first gate insulating film.

3. The semiconductor device of claim 1 , wherein

the second gate insulating film includes a first underlying film formed on the second active region, and the second high dielectric constant film formed on the first underlying film, and

the first underlying film has a thickness greater than that of the second high dielectric constant film.

4. The semiconductor device of claim 3 , wherein

the first gate insulating film includes a second underlying film formed on the first active region, and the first high dielectric constant film formed on the second underlying film, and

the second underlying film has a thickness smaller than those of the first high dielectric constant film and the first underlying film.

5. The semiconductor device of claim 1 , wherein the first gate electrode has a width in the gate length direction smaller than that of the second gate electrode.

6. The semiconductor device of claim 1 , wherein the first active region has a width in the gate width direction smaller than that of the second active region.

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

an isolation region formed in the semiconductor substrate to surround each of the first and second active regions,

wherein the first gate electrode is formed on the first active region and the isolation region,

the second gate electrode is formed on the second active region and the isolation region, and

the first gate electrode protruding above the isolation region has a protrusion amount smaller than that of the second gate electrode protruding above the isolation region.

8. The semiconductor device of claim 1 , wherein

the first offset sidewall has a width which is the same as that of the third offset sidewall, and

the second offset sidewall has a width which is smaller than or the same as that of the fourth offset sidewall.

9. The semiconductor device of claim 1 , wherein

the first offset sidewall has a width greater than that of the second offset sidewall, and

the third offset sidewall has a width greater than that of the fourth offset sidewall.

10. The semiconductor device of claim 1 , wherein

the first extension regions have a diffusion depth smaller than that of the second extension regions.

11. The semiconductor device of claim 1 , wherein the first extension regions have an impurity concentration higher than that of the second extension regions.

12. The semiconductor device of claim 1 , wherein

the first gate electrode has a rectangular shape as viewed from above, and

the second gate electrode has a rectangular shape with rounded corners as viewed from above.

13. The semiconductor device of claim 1 , wherein the first MIS transistor has a power supply voltage lower than that of the second MIS transistor.

14. The semiconductor device of claim 1 , wherein

the first gate electrode includes a first metal film formed on the first gate insulating film, and a first silicon film formed on the first metal film, and

the second gate electrode includes a second metal film formed on the second gate insulating film, and a second silicon film formed on the second metal film.

15. The semiconductor device of claim 1 , wherein the first gate insulating film includes an adjustment metal.

16. The semiconductor device of claim 15 , wherein

the first and second MIS transistors are each an n-type MIS transistor, and

the adjustment metal is lanthanum.

17. The semiconductor device of claim 15 , wherein

the first and second MIS transistors are each a p-type MIS transistor, and

the adjustment metal is aluminum.