Source/drain regions for a field effect transistor are defined in a semiconductor substrate with a channel region interposed therebetween. A first gate electrode is formed over the semiconductor substrate with an insulating film sandwiched therebetween and has a gate length shorter than the length of the channel region. A ferroelectric film is formed to cover the first gate electrode and to have both side portions thereof make contact with the insulating film. A second gate electrode is formed to cover the ferroelectric film.