Semiconductor device and method for manufacturing the same

1 . A semiconductor device, comprising:

a semiconductor substrate;

a p-type active region and an n-type active region which are formed in the semiconductor substrate;

a first MISFET including a first gate insulating film formed on the p-type active region and a first gate electrode formed on the first gate insulating film and including a first electrode formation film containing a metal element; and

a second MISFET including a second gate insulating film formed on the n-type active region and a second gate electrode formed on the second gate insulating film and including a second electrode formation film containing the metal element and having an oxygen content higher than the first electrode formation film.

2 . The semiconductor device of claim 1 ,

wherein the first electrode formation film has a work function smaller than the second electrode formation film.

3 . The semiconductor device of claim 2 ,

wherein the metal element is Ta.

4 . The semiconductor device of claim 3 ,

wherein the second electrode formation film further contains C.

5 . The semiconductor device of claim 4 ,

wherein the first electrode formation film further contains C.

6 . The semiconductor device of claim 1 ,

wherein the first gate insulating film and the second gate insulating film contain at least one selected from the group consisting of HfO 2 , HfSiO, and HfSiON.

7 . The semiconductor device of claim 1 ,

wherein the first gate insulating film and the second gate insulating film contain La.

8 . The semiconductor device of claim 1 ,

wherein the first gate insulating film and the second gate insulating film contain Zr.

9 . The semiconductor device of claim 1 ,

wherein an oxygen content of the first electrode formation film is 2% or lower, and the oxygen content of the second electrode formation film is in a range between 10% and 30%, both inclusive.

10 . The semiconductor device of claim 1 ,

wherein the first gate electrode further includes a third electrode formation film formed on or above the first electrode formation film, and

the second gate electrode further includes a fourth electrode formation film formed on or above the second electrode formation film.

11 . The semiconductor device of claim 10 ,

wherein at least one of the third electrode formation film and the fourth electrode formation film contains metal.

12 . The semiconductor device of claim 10 ,

wherein the first gate electrode further includes an intermediate film formed between the first electrode formation film and the third electrode formation film.

13 . A method for manufacturing a semiconductor device including a semiconductor substrate, a p-type active region, an n-type active region, a first MISFET including a first gate insulating film and a first gate electrode, and a second MISFET including a second gate insulating film and a second gate electrode, the method comprising the steps of:

(a) forming a gate insulating film on the semiconductor substrate after the p-type active region and the n-type active region are formed in the semiconductor substrate;

(b) forming a first electrode formation film on a part of the gate insulating film which is located on the p-type active region, the first electrode formation film containing a metal element;

(c) forming a second electrode formation film on a part of the gate insulating film which is located on the n-type active region, the second electrode formation film containing the metal element and having an oxygen content higher than the first electrode formation film; and

(d) removing a part of the first electrode formation film, a part of the second electrode formation film, and a part of the gate insulating film to form on the p-type active region the first gate electrode provided on the first gate insulating film and including the first electrode formation film and form on the n-type active region the second gate electrode provided on the second gate insulating film and including the second electrode formation film.

14 . The semiconductor device manufacturing method of claim 13 ,

wherein the step (b) includes the steps of:

(b1) forming the first electrode formation film on each of the parts of the gate insulating film which are located on the p-type active region and the n-type active region; and

(b2) removing the first electrode formation film with the part located on the p-type active region left, and

the step (c) includes the steps of:

(c1) forming the second electrode formation film on the first electrode formation film and the gate insulating film; and

(c2) removing the second electrode formation film with the part located on the n-type active region left.

15 . The semiconductor device manufacturing method of claim 13 ,

wherein the step (b) includes the step of forming the first electrode formation film on each of the parts of the gate insulating film which are located on the p-type active region and the n-type active region, and

the step (c) includes the step of oxidizing a part of the first electrode formation film which is located on the n-type active region to form the second electrode formation film containing the metal element and having an oxygen content higher than the first electrode formation film.

16 . The semiconductor device manufacturing method of claim 15 ,

wherein in the step (c), the part of the first electrode formation film which is located on the n-type active region is oxidized by performing thermal treatment under an oxygen atmosphere.

17 . The semiconductor device manufacturing method of claim 15 ,

wherein in the step (c), the part of the first electrode formation film which is located on the n-type active region is oxidized by injecting an oxygen ion.

18 . The semiconductor device manufacturing method of claim 13 , wherein the metal element is Ta.