Method of fabricating semiconductor device having low-resistance gate

Abstract

The method of fabricating a semiconductor device, includes the steps of (a) forming gate oxides on regions separated by device isolation regions, (b) depositing an amorphous silicon or a polysilicon film, (c) depositing a removable space-forming film over the silicon film, (d) patterning the space-forming film and the silicon film into the same shape to form a gate electrode comprising the thus patterned space-forming film and silicon film, (e) depositing a silicon nitride film, (f) etching the silicon nitride film to form a first sidewall around a sidewall of the gate electrode, (g) depositing a silicon oxide film, (h) etching the silicon oxide film to form a second sidewall around and onto the first sidewall, (i) etching the space-forming film with hydrofluoric anhydride for removal so that the silicon film is exposed and the first sidewall remains unremoved, (j) forming source/drain regions, and (k) selectively depositing a refractory metal or metal silicide film on the silicon film and the source/drain regions. The method makes it easy to cause the first sidewall to have higher height than the amorphous or polysilicon film to thereby form low-resistance gate electrode and diffusion layers, resulting in that the gate electrode is not short-circuited with the diffusion layers.