Fabrication process of a semiconductor device

A method of fabricating a semiconductor device, comprising:

• forming a device isolation structure on a substrate such that said device isolation structure defines a device region in the form of a silicon surface;
• forming a gate electrode over said device region via a gate insulation film formed on said silicon surface in said device region;
• forming first and second sidewall insulation films on respective sidewall surfaces of said gate electrode;
• forming a source region and a drain region of an identical conductivity type in said silicon substrate at respective outer sides of said first sidewall insulation film and said second sidewall insulation film;
• and
• forming first and second nickel monosilicide layers primarily of NiSi on respective surfaces of said source and drain regions,
• wherein said step of forming said first and second nickel monosilicide layers comprises the steps of:
• depositing a metallic nickel film on said substrate to cover said first and second diffusion regions and further said gate electrode including said first and second sidewall insulation films;
• annealing said metallic nickel film in a silane gas ambient at a temperature not exceeding 220° C. to form a first nickel silicide layer, a second nickel silicide layer and a third nickel silicide layer of a composition primarily of Ni2Si respectively on a surface of said source region, a surface of said drain region and also on a surface of said metallic nickel film,
• removing, after said step of forming said first through third nickel silicide layers, said metallic nickel film by a wet etching process together with said third nickel silicide film;
• and
• converting said first and second nickel silicide layers of said source and drain regions respectively to first and second nickel monosilicide layers by conducting a thermal annealing process.