PURPOSE: To suppress a short channel effect, to suppress the increase in sheet resistance in source and drain diffused regions and to prevent the decrease in current driving capability of an MOSFET, by coating a semiconductor substrate only in the vicinity of a gate electrode with a thin insulating film, and implanting ions.

CONSTITUTION: On a semiconductor substrate 1, a gate insulating film 2 and a gate electrode 3 are formed. On the semiconductor substrate 1 including the gate electrode 3, a thin first insulating film 4 is formed. A thick second insulating film 5 is formed on the first insulating film 4. Then the first and second insulating films 4 and 5 undergo anisotropic etching, and a side wall is formed on the gate electrode 3. Then, a part of the second insulating film 5 forming the side wall is removed. With the first insulating film 4 and the gate electrode 3 as masks, ions are implanted, and an ion implanted region 6 is formed. As said first insulating film 4, e.g., an oxide film is used. As the second insulating film 5, e.g., a nitride film is used. Thus, a shallow junction part and a deep junction part can be formed. A short channel effect and the decrease in current driving capability of the MOSFET due to the increase in sheet resistance of the source and the drain can be suppressed st at the same time.