Method of preventing leakage current of a metal-oxide semiconductor transistor

A method of fabricating a MOS transistor on a substrate comprising:

• sequentially forming a gate oxide layer and a gate on the substrate;
• performing a first ion implantation process to form a first doped region in the substrate;
• forming a liner layer to cover the substrate;
• sequentially forming a dielectric layer and a sacrificial layer on the liner layer;
• forming a L-shaped spacer on either side of the gate;
• performing a first etching process to remove portions of the liner layer not covered by the L-shaped spacer;
• performing a second ion implantation process to simultaneously form a second doped region and a third doped region in the substrate;
• and
• performing a salicide process to form a silicide layer on the gate and on portions of the substrate surface above the third doped region.