PURPOSE: To reduce the short channel effect by utilizing the unevenness caused on the surface of the semiconductor substrate through the selective oxidation method to form the gate at the concave part and the drian and source at the convex part each and then reducing the protrusion of the depletion layer at the drain side.

CONSTITUTION: Selective oxidation 12 is applied to Si substrate 1 via the double- layer mask of SiO2 and Si3N4, and then drain 2 and source 3 are formed by the opposite conducting diffusion to substrate 1. Then field oxide film 5 of several hundreds of is provided on layer 2 and 3, and gate oxide film 4 is formed through the selective etching. Finally, Al electride 6 and 7 are formed after drilling the opening to film 5. With this method, gate film 4 secures the sam level as the drain and the source, and depletion layer 8 has reduced protrusion right under film 4 at the side of drain 2. And the characteristic deterioration can be lessened greatly for the short-channel MOSFET, thus obtaining a high-performance MOSIC. The edge angle of film 12 ddpends on the thickness of the foundation oxide film and the formation temperature of film 12. And the larger angle the more the characteristics or the forming accuracy increases for the device.