Oxide film formation method

An oxide film formation method for forming an oxide film on a film formation surface of a film formation target contained in a chamber, the oxide film formation method comprising:

• forming the oxide film such that the oxide film includes a first film formed on the film formation surface to have a film thickness of 2 nm or thicker and a second film formed on a surface of the first film, wherein:
• the first film is formed by a first film formation method being an atomic layer deposition method and including a first raw material gas supply process, a first raw material gas purge process, a first oxidizer supply process, and a first oxidizer purge process;
• the first raw material gas supply process includes supplying to an inside of the chamber, raw material gas containing an element to compose the oxide film, and forming a first adsorption layer of the raw material gas on the film formation surface;
• the first raw material gas purge process includes removing from the film formation surface, excess gas of the raw material gas supplied in the first raw material gas supply process and gas yielded due to adsorption of the raw material gas on the film formation surface;
• the first oxidizer supply process includes supplying ozone gas of 80 volume % or higher to the inside of the chamber and oxidizing the first adsorption layer;
• the first oxidizer purge process includes removing from the film formation surface, excess gas of the ozone gas supplied in the first oxidizer supply process and gas yielded due to oxidation of the first adsorption layer;
• the second film is formed by a second film formation method being an atomic layer deposition method different from the first film formation method or being a chemical vapor deposition method;
• and
• the second film formation method employs as an oxidizer, OH radicals yielded by a radical reaction between ozone gas of 80 volume % or higher and unsaturated hydrocarbon gas.