PURPOSE: To uniformly form an insulating oxide film and a gate oxide film in a good shape thereby to obtain a dynamic memory having high insulating breakdown strength and preferable characteristics by using a plasma oxidation to form an insulating oxide film between a capacity electrode and a transfer gate and a gate oxide film of the transfer gate.

CONSTITUTION: A silicon substrate 1 is thermally oxidized to form an oxide film 2, and a nitride film 3 is then grown on the film 2. A polycrystalline silicon film is deposited on the film 3, and a capacity electrode 4 is formed with an oxide film 5 as a mask. Then, the whole surface is oxidized in the same degree in both the nitride film surface and the polycrystalline silicon film surface, and an insulating oxide film 6 of preferable shape is formed uniformly on the polycrystalline silicon film side of the electrode 4 near the film 3. Then, with the films 6 on the front and side surfaces of the electrode 4 as masks the part on the film 3 of the film 6, the film 3, and the film 3 are sequentially removed by etching. Further, a gate oxide film 7 is formed on the substrate 1. After a polycrystalline silicon film is grown, a transfer gate 8 is formed by etching.