Method of manufacturing a semiconductor device including a silicon pillar

1. A method of manufacturing a semiconductor device, comprising:

forming a silicon pillar on a substrate;

forming a protective film which covers an upper end portion and a lower end portion of a side surface of the silicon pillar;

forming a constricted portion by anisotropic etching in a portion of the side surface of the silicon pillar which is not covered with the protective film, after forming the protective film;

removing the protective film after forming the constricted portion;

forming a gate oxide film which covers the side surface of the silicon pillar in which the constricted portion is formed, after removing the protective film; and

forming a gate electrode which covers the gate oxide film.

2. The method according to claim 1 , wherein forming of the protective film comprises:

forming a first film which covers an upper surface of the substrate and the side surface of the silicon pillar;

forming a second film which covers the side surface of the silicon pillar which is covered with the first film;

forming a third film which covers the portion of the substrate which is covered with the first film after forming the second film to produce the protective film at the interface between the first film and the upper end portion of the side surface of the silicon pillar, and at the interface between the first film and the lower end portion of the side surface of the silicon pillar; and

removing the first film and the second film to expose the protective film.

3. The method according to claim 2 , wherein the first film and the third film are oxide films and the second film is a nitride film.