Method of forming silicon film

A method of forming a silicon film on a target surface of a target object, comprising:

• performing an impurity removal process on the target surface of the target object using an oxygen gas and a hydrogen gas;
• forming the silicon film on the target surface to which the impurity removal process has been performed by supplying a silicon raw material gas to the target surface of the target object,
• wherein the performing a impurity removal process and the forming the silicon film are performed within a single processing chamber, and
• wherein after performing the impurity removal process before forming the silicon film on the target surface, the processing chamber is purged with an inert gas.