PURPOSE:To prevent the production of career caused by the collision of electron and crystal lattice, to decrease current leakage of drain and to improve the withstanding voltage, by forming deeply without overlapping drain and source layer with gate electrode. CONSTITUTION:On insulating separation 6 of P type Si substrate 5, and surface oxide film 4, a conductive poly Si 1 is mounted and performing an Si3N4 mask 7 to etch the layer 1 selectively. By performing heat to form an SiO2 8 at the side face, N layers 2', 3' are formed by ion implantation using mask 7. Taking the mask 7 off, the layers 2, 3 are diffusedly, heatedly, formed. At this time, the length l of SiO2 8 and diffusing length l' of side direction are selected almost equal. In this composition, the gate electrode 1 and the end of drain sources 2, 3 are stationed in the same position, and the layers 2, 3 can be formed deeply. Therefore, the capacity caused by overlapping becomes very small, and the cross sectional area of acting region increases, collision of ions is controlled, and increase of current leakage and decrease of withstanding voltage are prevented.