A semiconductor substrate SB having an interlayer insulating film 3 formed thereon is accommodated in a chamber, and a large quantity of a nitrogen gas is introduced into the chamber to purge air or the like in the chamber and to replace an atmospheric gas in the chamber with a nitrogen gas. 層間絶縁膜3を形成した状態の半導体基板SBをチャンバー内に収容し、大量の窒素ガスをチャンバー内に導入してチャンバー内の空気等をパージし、チャンバー内の雰囲気ガスを窒素ガスに置換する。 - 特許庁