Semiconductor device and method for fabricating the same
A semiconductor device includes a first MIS transistor formed on a first active region, and a second MIS transistor formed on a second active region. The first MIS transistor includes a first gate insulating film, and a first gate electrode including a first metal film and a first silicon film. The second MIS transistor includes a second gate insulating film, and a second gate electrode including the first metal film, a second metal film, and a second silicon film.
1. A semiconductor device, comprising:
a first MIS transistor formed on a first active region of a semiconductor substrate; and
a second MIS transistor formed on a second active region of the semiconductor substrate, wherein
the first MIS transistor includes:
a first gate insulating film formed on the first active region; and
a first gate electrode including 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 MIS transistor includes:
a second gate insulating film formed on the second active region; and
a second gate electrode including the first metal film formed on the second gate insulating film, a second metal film formed on the first metal film, and a second silicon film formed on the second metal film.
2. The semiconductor device of claim 1 , wherein
the first metal film and the second metal film are made of the same metal material, and
a density of the first metal film is lower than a density of the second metal film.
3. The semiconductor device of claim 1 , wherein the first metal film and the second metal film are made of different metal materials.
4. The semiconductor device of claim 1 , wherein the first gate electrode further includes a conductive film formed on the first metal film, and a second metal film formed between the conductive film and the first silicon film.
5. The semiconductor device of claim 4 , wherein the conductive film is formed of a silicon film.
6. The semiconductor device of claim 1 , wherein a thickness of the first metal film is not less than 1 nm and not more than 5 nm.
7. The semiconductor device of claim 1 , wherein the first gate insulating film and the second gate insulating film are made of the same insulating material.
8. The semiconductor device of claim 1 , wherein each of the first gate insulating film and the second gate insulating film includes a high dielectric constant film made of a metal oxide having a specific dielectric constant of not less than 10.
9. The semiconductor device of claim 1 , wherein
the first gate electrode further includes a first silicide film formed in an upper portion of the first silicon film, and
the second gate electrode further includes a second silicide film formed in an upper portion of the second silicon film.
10. The semiconductor device of claim 1 , further comprising:
an insulating film formed over the semiconductor substrate so as to cover the first gate electrode and the second gate electrode.
11. The semiconductor device of claim 10 , further comprising:
first sidewalls formed on side surfaces of the first gate electrode, and each having an L-shaped cross-sectional shape; and
second sidewalls formed on side surfaces of the second gate electrode, and each having an L-shaped cross-sectional shape, wherein
the insulating film is formed in contact with respective upper surfaces of the first sidewalls and the second sidewalls.
12. The semiconductor device of claim 1 , wherein
the first MIS transistor is an n-type MIS transistor, and
the second MIS transistor is a p-type MIS transistor.