Semiconductor device

A semiconductor device comprising:

• a semiconductor region of first conductivity type provided in a semiconductor layer of first conductivity type;
• a first semiconductor region of second conductivity type provided in the semiconductor region of first conductivity type;
• a second semiconductor region of second conductivity type provided in the semiconductor layer of first conductivity type spaced from the semiconductor region of first conductivity type;
• a third semiconductor region of second conductivity type provided between the semiconductor region of first conductivity type and the second semiconductor region of second conductivity type in the semiconductor layer of first conductivity type, and having a lower impurity concentration than the second semiconductor region of second conductivity type;
• a first insulating layer provided in the third semiconductor region of second conductivity type;
• a control electrode provided on the semiconductor region of first conductivity type arranged between the first semiconductor region of second conductivity type and the third semiconductor region of second conductivity type via a second insulating layer;
• a first auxiliary electrode provided on the first insulating layer spaced from the control electrode;
• a first main electrode electrically connected to the first semiconductor region of second conductivity type;
• and
• a second main electrode electrically connected to the second semiconductor region of second conductivity type,
• when a direction substantially parallel to a direction of a main current flowing between the first semiconductor region of second conductivity type and the second semiconductor region of second conductivity type being defined as a first direction, and
• a direction substantially perpendicular to the first direction and substantially parallel to a major surface of the semiconductor layer of first conductivity type being defined as a second direction,
• most part of the first insulating layer having a width along the second direction substantially narrowing from the control electrode toward the second main electrode.