Method of fabricating mosfet

A method for fabricating a metal-oxide-semiconductor field-effect transistor (MOSFET), comprising:

• providing a substrate and forming therein an STI region that delimits an active area which contains a channel region;
• successively forming a gate dielectric layer and a polysilicon layer over both the STI region and the active area, wherein the polysilicon layer is a layer of undoped polysilicon, lightly-doped polysilicon or a combination thereof;
• defining a portion of the polysilicon layer above an channel edge between the channel region and the STI region as a first polysilicon layer and a remaining portion of the polysilicon layer as a second polysilicon layer, forming a gate by masking at least portions of the first and second polysilicon layers located above the channel region, and etching away the unmasked portions of the first and second polysilicon layers;
• and
• masking a portion of the gate above the channel edge and performing a source/drain (S/D) implantation on both the unmasked portion of the gate and portions of the active area on both sides of the gate to form source and drain regions, wherein ions implanted to form the source and drain regions are of a same conductivity type as ions in the lightly-doped polysilicon, and wherein the first polysilicon layer in the gate is partially unaffected by the S/D implantation while the second polysilicon layer is entirely converted into a polysilicon layer doped with ions implanted in the S/D implantation.