Semiconductor device including first and second dummy trench gates

A semiconductor device comprising:

• a semiconductor substrate including at least:
• a first semiconductor layer of a first conductivity type;
• a second semiconductor layer of the first conductivity type on the first semiconductor layer and having a peak concentration of impurities that is higher than a peak concentration of impurities of the first semiconductor layer;
• a third semiconductor layer of a second conductivity type on the second semiconductor layer;
• and
• a fourth semiconductor layer of the first conductivity type that is selectively provided in an upper layer portion of the third semiconductor layer;
• plural trench gates passing through the fourth semiconductor layer and the third semiconductor layer in a thickness direction to terminate in the second semiconductor layer;
• a first dummy trench gate passing through the third semiconductor layer and the second semiconductor layer in the thickness direction to terminate in the first semiconductor layer;
• a second dummy trench gate passing through the third semiconductor layer in the thickness direction to terminate in the second semiconductor layer;
• a first main electrode in contact with at least the fourth semiconductor layer;
• and
• a second main electrode provided on the semiconductor substrate on a side opposite to the first main electrode in the thickness direction,
• the first and second dummy trench gates being disposed between the trench gates arrayed and being electrically connected to the first main electrode.