Fabrication process of a semiconductor device

A method of fabricating a semiconductor device, comprising the steps of:

• 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 in said substrate within said device region at respective outer sides of said first and second sidewall insulation films;
• and
• forming first and second nickel monosilicide layers primarily of a NiSi phase respectively on a surface of said source region and a surface of said drain region,
• said step of forming said first and second nickel monosilicide layers comprises the steps of
• depositing a metallic nickel film on said substrate so as to cover said source and drain regions and further said gate electrode including said first and second sidewall insulation films;
• forming first and second nickel silicide layers primarily of a Ni2Si phase respectively on said surface of said source region and said surface of said drain region by applying a thermal annealing process to said metallic nickel film;
• removing said metallic nickel film after formation of said first and second nickel silicide layers by a selective wet etching process;
• and
• converting said first and second nickel silicide layers respectively to a first and second nickel monosilicide layers in said source and drain regions by way of a thermal annealing process conducted in a silane gas ambient.