A semiconductor substrate includes a first principal plane and a second
principal plane opposite this first principal plane. A first semiconductor
region is formed on the first principal plane of the semiconductor
substrate. Second and third semiconductor regions are formed separately
from each other on the first semiconductor region. A gate electrode is
formed, via a gate insulator, on the first semiconductor region between
the second semiconductor region and the third semiconductor region. An
electric conductor is formed up to the semiconductor substrate from the
second semiconductor region and electrically connects the second
semiconductor region with the semiconductor substrate. A first main
electrode is formed on the second principal plane of the semiconductor
substrate and is electrically connected to the semiconductor substrate. A
second main electrode is formed on the first semiconductor region via
insulators and is electrically connected to the third semiconductor
region.
