Semiconductor device and method for fabricating the same
View Patent ↗A semiconductor device includes: a first gate insulating film on a first region of a semiconductor substrate; a first gate electrode on the first gate insulating film; a second gate insulating film on a second region of the semiconductor substrate; and a second gate electrode on the second gate insulating film. The first gate insulating film includes a first insulating film composed of a first material containing a first metal, and the second gate insulating film includes a second insulating film composed of the first material and a second material containing a second metal.
1. A method for fabricating a semiconductor device comprising the steps of:
(a) sequentially forming a first material film and a first conductive film over the entire surface of a semiconductor substrate, the first material film being insulative and containing a first metal, and the semiconductor substrate including a first region and a second region separate from each other by a device isolation region;
(b) removing a portion of the first conductive film formed over the second region;
(c) after step (b), sequentially forming a second material film containing a second metal and a second conductive film over the entire surface of the semiconductor substrate;
(d) after step (c), removing portions of the second conductive film and the second material film formed over the first region;
(e) after step (d), forming a polysilicon film over the entire surface of the semiconductor substrate; and
(f) selectively removing the polysilicon film, the first conductive film, the first material film, the second conductive film, and the second material film to form a first gate electrode including the polysilicon film and the first conductive film and a first gate insulating film including the first material film over the first region and to form a second gate electrode including the polysilicon film and the second conductive film and a second gate insulating film including the second material film and the first material film over the second region.
2. The method of claim 1 , further comprising the step of:
(g) after step (f), mixing the second material film and the first material film by thermal diffusion to form a mixed film of the first material film and the second material film.
3. The method of claim 1 , wherein
in step (c), wet etching using a wet etchant is performed, and
the first material film is smaller in etch rate with respect to the wet etchant than the second material film.