Semiconductor device

A semiconductor device comprising:

• a semiconductor substrate provided with an emitter electrode and a gate electrode;
• a carrier stored layer of a first conductivity type disposed on an upper surface side of the semiconductor substrate;
• a base layer of a second conductivity type disposed on the upper surface side of the carrier stored layer;
• a source layer of a first conductivity type disposed on the upper surface side of the base layer;
• an upper-stage active portion disposed on a first insulating film along an inner wall of an upper portion of a trench penetrating the source layer, the base layer, and the carrier stored layer, the upper-stage active portion being upper-stage polysilicon connected to the gate electrode;
• and
• lower-stage polysilicon disposed on a second insulating film along an inner wall of a lower portion of the trench, the lower-stage polysilicon provided with a third insulating film disposed between the upper-stage active portion and the lower-stage polysilicon,
• wherein the lower-stage polysilicon is any one of a lower-stage dummy portion connected to the emitter electrode, a lower-stage active portion connected to the gate electrode, and a lower-stage floating portion electrically floated, and
• wherein a lower end of the upper-stage active portion is positioned below a lower end of the carrier stored layer.