Seasoning method for film-forming apparatus

A seasoning method for a film-forming apparatus configured to form a silicon nitride film on a substrate placed in a processing chamber, comprising:

• supplying a cleaning gas into the processing chamber, and etching the silicon nitride film attached to an inner wall of the processing chamber while converting the cleaning gas into a plasma state;
• supplying a silicon-containing gas into the processing chamber, and depositing an amorphous silicon film on the inner wall of the processing chamber while converting the silicon-containing gas into a plasma state;
• supplying the silicon-containing gas into the processing chamber, while supplying a nitrogen-containing gas in a gradually increasing manner up to a predetermined flow rate, and thus depositing, on the amorphous silicon film, a silicon nitride film with the nitrogen content gradually increasing in a thickness direction, while converting the silicon-containing gas and the nitrogen-containing gas into a plasma state;
• and
• supplying a rare gas into the processing chamber and maintaining a plasma state of the rare gas until film formation of the silicon nitride film on the substrate is initiated.