Field-effect transistor and fabricating method thereof

A method for fabricating a field-effect transistor comprising:

• forming a gate dielectric layer and a barrier layer on a substrate in sequence;
• forming a first silicon layer on and in contact with the barrier layer;
• performing a thermal treatment to form a silicide layer between the barrier layer and the first silicon layer;
• forming a second silicon layer on and in contact with the first silicon layer;
• patterning the second silicon layer, the first silicon layer, the barrier layer and the gate dielectric layer to form a dummy gate structure;
• and
• forming a metal gate electrode to take the place of a patterned second silicon layer and a patterned first silicon layer.