Semiconductor device

A semiconductor device comprising:

• a semiconductor part;
• a first electrode provided on the semiconductor part;
• a second electrode, the semiconductor part being provided between the first electrode and the second electrode;
• and
• a plurality of control electrodes provided between the semiconductor part and the second electrode, the control electrodes each being electrically isolated from the semiconductor part by a first insulating film, the control electrodes each being electrically isolated from the second electrode by a second insulating film,
• the second electrode including a center portion and a peripheral portion, the peripheral portion being provided at an outer side of the center portion in a direction along a surface of the semiconductor part,
• the semiconductor part including a first region and a second region, the first region being provided between first electrode and the center portion of the second electrode, the second region being provided between the first electrode and the peripheral portion of the second electrode,
• the control electrodes including first and second control electrodes, the first control electrode being provided between the center portion of the second electrode and the first region of the semiconductor part, the second control electrode being provided between the peripheral portion of the second electrode and the second region of the semiconductor part,
• the semiconductor part including a first semiconductor layer of a first conductivity type, a first second semiconductor layer of a second conductivity type in the first region, a second second semiconductor layer of the second conductivity type in the second region, a first third semiconductor layer of the first conductivity type in the first region, and a second third semiconductor layer of the first conductivity type in the second region,
• the first second semiconductor layer being provided between the first semiconductor layer and the second electrode, the first second semiconductor layer facing the first control electrode with a first insulating film interposed,
• the second second semiconductor layer being provided between the first semiconductor layer and the second electrode, the second second semiconductor layer facing the second control electrode with another first insulating film interposed,
• the first third semiconductor layer being selectively provided between the first second semiconductor layer and the second electrode, the first third semiconductor layer contacting the first insulating film,
• the second third semiconductor layer being selectively provided between the second second semiconductor layer and the second electrode, the second third semiconductor layer contacting said another first insulating film,
• the first insulating film having a first thickness in a direction from the first second semiconductor layer to the first control electrode,
• said another first insulating film having a second thickness in a direction from the second second semiconductor layer to the second control electrode, the second thickness being thicker than the first thickness.