Method of manufacturing semiconductor device

A method of manufacturing a semiconductor device, comprising the steps of:

• preparing a substrate composed of silicon carbide;
• forming an active layer on said substrate;
• forming a gate insulating film on said active layer;
• forming a gate electrode on said gate insulating film;
• forming a contact electrode on said active layer, in contact with said active layer;
• forming an interconnection on said contact electrode, in contact with said contact electrode,
• said step of forming an interconnection including the steps of
• forming a conductor film on said contact electrode, and
• processing said conductor film by etching said conductor film with reactive ion etching;
• forming a passivation film to cover said conductor film;
• and
• performing annealing or heating said substrate to a temperature not lower than 50° C. to lower a leakage current after the step of processing said conductor film, wherein said step of annealing or heating said substrate is performed after said step of forming said passivation film.