Semiconductor device and method for manufacturing semiconductor device

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

forming an amorphous silicon film on a semiconductor substrate, the amorphous silicon film containing a metallic element and having a first region near a lower surface thereof, a second region near an upper surface thereof, and a third region between the first and second regions, the metallic element contained in the amorphous silicon film having a density distribution in a thickness direction of the amorphous silicon film, a peak of the density distribution existing in the first or third region; and

oxidizing the amorphous silicon film containing the metallic element to form a silicon oxide film containing the metallic element.

2. The method according to claim 1 , further comprising nitriding a surface of the silicon oxide film.

3. The method according to claim 2 , wherein the surface of the silicon oxide film is nitrided using plasma.

4. The method according to claim 1 , wherein the amorphous silicon film is formed by a CVD method using a metal source and a silicon source.

5. The method according to claim 4 , wherein the metal source is a halide of the metallic element, and the silicon source is a hydride of silicon.

6. The method according to claim 1 , wherein the amorphous silicon film is oxidized using an active oxidation species.