Filling method and film forming apparatus

A method of filling a recess formed in a surface of a substrate with a metal oxide film, the method comprising:

• loading the substrate into a processing container;
• forming the metal oxide film by supplying a metallic raw material gas and an oxidant to the recess;
• and
• etching a part of the metal oxide film by supplying an etching gas including at least one selected from a group of SOCl2 and (COCl)2 to the metal oxide film,
• wherein, in the forming and the etching, the substrate is heated to 500 degrees C. or higher,
• wherein the metal oxide film is at least one selected from a group of aluminum oxide film, hafnium oxide film, and zirconium oxide film, and
• wherein, in the etching, the metal oxide film formed on the recess is selectively etched with respect to the metal oxide film formed on an inner wall of the processing container.