Semiconductor device

A semiconductor device, comprising:

• a semiconductor part;
• a first electrode provided on a back surface of the semiconductor part;
• a second electrode provided on a front surface of the semiconductor part;
• a control electrode provided between the semiconductor part and the second electrode, the semiconductor part having a trench at the front surface side, the control electrode being provided in the trench and electrically insulated from the semiconductor part by a first insulating part;
• a third electrode provided inside the trench, the third electrode having a bottom end provided at a bottom of the trench, the third electrode being provided apart from the control electrode, a distance between the third electrode and the first electrode being smaller than a distance between the control electrode and the first electrode, the third electrode being electrically insulated from the semiconductor part by a second insulating part and electrically insulated from the control electrode by a third insulating part;
• a first insulating film provided in the second insulating part, the first insulating film being provided between the semiconductor part and the third electrode;
• a second insulating film shared by the second insulating part and the third insulating part, the second insulating film being provided between the first insulating film and the third electrode and between the control electrode and the third electrode;
• and
• a third insulating film shared by the second insulating part and the third insulating part, the third insulating film being provided between the first and second insulating films and between the control electrode and the second insulating film, the third insulating film being different in composition from the first insulating film and the second insulating film;
• the semiconductor part including a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, and a third semiconductor layer of the first conductivity type,
• the first semiconductor layer extending between the first and second electrodes,
• the second semiconductor layer being provided between the first semiconductor layer and the second electrode,
• the third semiconductor layer being selectively provided between the second semiconductor layer and the second electrode,
• the first insulating part being provided between the second semiconductor layer and the control electrode,
• the second insulating part being provided between the third electrode and the first semiconductor layer, the second insulating part including the first to third insulating films at the bottom of the trench with the third insulating film being provided between the first and second insulating films at the bottom of the trench, the third insulating film being provided between the bottom end of the third electrode and the first semiconductor layer.