Insulated gate type semiconductor device and process for producing the device

摘要

A side insulation layer is formed on a side wall of a gate electrode by oxidizing (or nitrizing) a substance of the gate electrode, so that the gate electrode is insulated from the semiconductor substrate with the side insulation layer and a gate insulation film. The gap between the gate electrode and the semiconductor substrate is greater around the side wall of the gate electrode than around the center thereof. The gap between the side wall of the gate electrode and the semiconductor substrate is densely filled with an insulating substance.