PURPOSE: To prevent a short channel effect and an electrode punch through phenomenon by oxidizing the surface and side surfaces of a gate electrode in advance, selectively glowing a single-crystalline silicon only in expected source/drain regions and converting the expected source/drain regions to diffused regions.

CONSTITUTION: A gate oxide film 13 is formed on the surface of a P-type silicon substrate 11 and a gate electrode 14 is formed on a part of the gate oxide film 13. Then, a thermal oxidation is performed in an oxygen atmosphere to form an oxide film 16 on a polysilicon gate electrode 14 and other oxide films are formed on expected source/drain regions. Thereafter, the epitaxial growth of single-crystalline silicon is performed in a mixed gas SiH4/HCl (3%), resulting in the growth of single-crystalline silicon 17. Then, an N-type impurity of a high density is ion-implanted into the silicon substrate 11 through the single- crystalline silicon 17. Thus, the single-crystalline silicon 17 and the surface of the silicon substrate 11 just below the single-crystalline silicon 17 are formed as source/drain diffusion layers 15.