Method of forming oxide film

A method of forming an oxide film by means of an oxide film forming apparatus having;

• (a) a substrate transfer portion,
• (b) a process chamber which communicates with the substrate transfer portion and is for thermally oxidizing a semiconductor layer on a surface of a substrate in a water vapor atmosphere, to form an oxide film, and
• (c) openable and closable partitioning means provided between the substrate transfer portion and the process chamber,
• the method comprising the steps of;
• (A) generating a water vapor atmosphere in the process chamber in a state where the partitioning means is closed, and transferring the substrate into the substrate transfer portion,
• (B) opening the partitioning means after the transfer of the substrate into the substrate transfer portion is completed, and transferring the substrate into the process chamber having the water vapor atmosphere,
• (C) thermally oxidizing the semiconductor layer on the surface of the substrate in the process chamber having the water vapor atmosphere, to form an oxide film having a predetermined thickness on the surface of the semiconductor layer, and
• (D) changing the atmosphere in the process chamber into an inert gas atmosphere, then transferring the substrate out of the process chamber, closing the partitioning means and transferring the substrate out of the substrate transfer portion.