A method of fabricating a field effect transistor, wherein a substrate with a gate is provided. A liner oxide layer and a first spacer are formed adjacent to the sides of the gate. An epitaxial silicon layer is formed at both sides of the gate in the substrate, while a shallow source/drain (S/D) extension junction is formed in the substrate below the epitaxial silicon layer. An oxide layer and a second spacer are formed to be closely connected to the first spacer and form the S/D region below the epitaxial silicon layer. A part of the epitaxial silicon layer is then transformed into a metal silicide layer, so as to complete the process of the field effect transistor.