Method for fabricating semiconductor device
A method for fabricating a semiconductor device includes the steps of: a) forming an insulating film on a semiconductor substrate; b) forming a first conductive film of a material which does not contain nitrogen on the insulating film; and c) forming a second conductive film of a material containing nitrogen on the first conductive film. The method further includes the step of d) patterning the first conductive film and the second conductive film to form a gate electrode and patterning the insulating film to form a gate insulating film.
1 . A method for fabricating a semiconductor device, comprising the steps of:
a) forming an insulating film on a semiconductor substrate;
b) forming a first conductive film of a material which does not contain nitrogen on the insulating film;
c) forming a second conductive film of a material containing nitrogen on the first conductive film; and
d) patterning the first conductive film and the second conductive film to form a gate electrode and patterning the insulating film to form a gate insulating film.
2 . The method of claim 1 , further comprising, between the step b) and the step c), the step e) of selectively etching the first conductive film to provide a region in the first conductive film on the semiconductor substrate which has a different thickness from a thickness of other regions of the first conductive film.
3 . The method of claim 2 , wherein the semiconductor substrate includes a region in which an n-type transistor is to be formed and a region in which a p-type transistor is to be formed, and
wherein, in the step e), the first conductive film is processed to have a smaller thickness in the region in which a p-type transistor is to be formed than a thickness in the region in which an n-type transistor is to be formed.
4 . The method of claim 3 , wherein, in the step of e), part of the first conductive film located in the region in which a p-type transistor is to be formed is removed.
5 . The method of claim 1 , wherein the first conductive film is formed of any one of tantalum, titanium, tungsten, a rare-earth element and silicide or carbide of tantalum, titanium, tungsten or the rare-earth element, or an alloy containing two or more of tantalum, titanium, tungsten, a rare-earth element and silicide or carbide of tantalum, titanium, tungsten or the rare-earth element.
6 . The method of claim 1 , wherein the second conductive film is formed of any one of tantalum nitride, titanium nitride, tungsten nitride and nitride of a rare-earth element, or an alloy containing two or more of tantalum nitride, titanium nitride, tungsten nitride and nitride of a rare-earth element.
7 . The method of claim 6 , wherein the second conductive film contains at least one of silicon or carbon.
8 . The method of claim 1 , wherein, in the step of b), the first conductive film is formed by physical vapor deposition.
9 . The method of claim 1 , wherein, in the step of c), the second conductive film is formed by physical vapor deposition, chemical vapor deposition or atomic layer deposition.
10 . The method of claim 1 , further comprising, between the step c) and the step d), the step f) of forming a third conductive film on the second conductive film.
11 . The method of claim 1 , further comprising, after the step e), the step g) of forming sidewalls on side surfaces of the gate electrode, respectively.
12 . The method of claim 11 , further comprising, after the step g), the steps of:
h) forming source/drain regions on both sides of the gate electrode in the semiconductor substrate, respectively, and
i) performing silicidation to the source/drain regions.