An MOS transistor with a fully silicided gate is produced by forming a silicide compound in the gate separately and independently of silicide portions located in source and drain zones of the transistor. To this end, the silicide portions of the source and drain zones are covered by substantially impermeable coatings. The coatings prevent the silicide portions of the source and drain zones from increasing in volume during separate and independent formation of the gate silicide compound. The silicide gate may thus be thicker than the silicide portions of the source and drain zones.