An isolation region is embedded in a semiconductor substrate. The height of
the upper face of the isolation region is substantially equal to the
height of the surface of the semiconductor substrate. A gate electrode is
formed on a gate insulating film and over the isolation region. A first
side face of the gate electrode is formed over the isolation region. A
second side face of the gate electrode is formed over the active region. A
field insulator is formed on the isolation region. A first side face of
the field insulator contacts with the first side face of the gate
electrode. A second side face of the field insulator is continuous with a
plane obtained by extending the side face of the isolation region. A
sidewall insulator has a sidewall contacting with the second side face of
the field insulator and the second side face of the gate electrode.
