the following steps are carried out : forming a gate electrode on a semiconductor substrate with a gate insulating film interposed therebetween , forming a dummy gate electrode on the semiconductor substrate with a dummy gate insulating film interposed therebeweeen and forming another dummy gate electrode on the semiconductor substrate with an insulating film for isolation interposed therebetween ; forming a metal film on the semiconductor while exposing the gate electrode and covering the dummy gate electrodes ; and subjecting the semiconductor substrate to heat treatment and thus siliciding at least an upper part of the gate electrode . since the gate electrode is silicided and the dummy gate electrodes are non - silicided , this restrains a short circuit from being caused between the gate electrode and adjacent one of the dummy gate electrodes .