The invention is directed to a method for forming a metal-oxide semiconductor field effect transistor. The method comprises steps of providing a substrate having a gate structure formed thereon, wherein a plurality of isolation structures are located in the substrate adjacent to both sides of the gate structure and then forming a first spacer on the sidewall of the gate structure. A portion of the substrate between the first spacer and the isolation structures is removed to form a recession and a source/drain layer is deposited in the recession, wherein the top surface of the source/drain layer is higher than the top surfaces of the isolation structures. A second spacer is formed on the isolation structures and at the sidewall of the source/drain layer and a metal silicide layer is formed on the source/drain layer.