The invention concerns a method of forming a field effect transistor comprising a gate (G) formed on an insulating layer, the gate having, in a zone in contact with the insulating layer, a semiconducting central zone (50) and lateral zones (48) in the length of the gate (G), the method comprising forming a gate (G) comprising a portion of insulating layer (32), a portion of semiconducting layer formed over the insulating layer (32), and a portion of mask layer formed over the semiconducting layer; performing an etching of the portion of the mask layer such that only a portion in the centre ofthe gate (G) remains; and reacting the semiconducting gate with a metal deposited over the gate.