Insulated gate bipolar transistor

An insulated gate bipolar transistor comprising:

• a first semiconductor layer of a first conductivity type having a first surface and a second surface on an opposite side to the first surface;
• a first trench extending from the first surface of the first semiconductor layer into the first semiconductor layer;
• a second trench extending from the first surface of the first semiconductor layer into the first semiconductor layer and adjacent to the first trench;
• a first base layer of a second conductivity type selectively formed on the first surface of the first semiconductor layer between the first trench and the second trench and exposed at a side wall of the first trench;
• a second base layer of the second conductivity type selectively formed on the first surface of the first semiconductor layer between the first trench and the second trench, exposed at a side wall of the second trench and adjacent to the first base layer via the first semiconductor layer;
• a first emitter layer of the first conductivity type selectively formed on a surface of the first base layer and exposed at the side wall of the first trench;
• a second emitter layer of the first conductivity type selectively formed on a surface of the second base layer and exposed at the side wall of the second trench;
• a first gate electrode provided on the first semiconductor layer, on the first base layer, and on the first emitter layer via a first gate insulating film in the first trench;
• a second gate electrode provided on the first semiconductor layer, on the second base layer, and on the second emitter layer via a second gate insulating film in the second trench and electrically connected to the first gate electrode;
• an interlayer insulating film provided on the first gate electrode and on the second gate electrode;
• a first insulating film provided on the first base layer and on the second base layer and covering the first surface of the first semiconductor layer between the first base layer and the second base layer;
• a second semiconductor layer of the second conductivity type provided on the second surface of the first semiconductor layer;
• a first electrode electrically connected to the second semiconductor layer;
• and
• a second electrode electrically connected to the first base layer, the second base layer, the first emitter layer, and the second emitter layer and insulated from the first surface of the first semiconductor layer by the first insulating film,
• the first trench, the second trench, the first base layer, and the second base layer having a striped structure extending in a first direction parallel to one another on the first surface of the first semiconductor layer,
• the first emitter layer extending in the first direction along the first trench,
• the second emitter layer extending in the first direction along the second trench,
• each of the first emitter layer and the second emitter layer having a striped structure of a single layer extending along the first direction,
• further comprising:
• a plurality of third base layers of the second conductivity type provided on the first surface of the first semiconductor layer and extending in a second direction orthogonal to the first direction to connect the first base layer and the second base layer;
• a third emitter layer of the first conductivity type selectively formed on a surface of at least one of adjacent third base layers out of the third base layers and connecting the first emitter layer and the second emitter layer,
• a contact layer of the second conductivity type provided on a portion of the first semiconductor layer sandwiched between the first base layer and the second base layer, and connected to the first base layer and the second base layer;
• and
• a conductor provided on the first semiconductor layer and the contact layer in a third trench via a second insulating film, the third trench going through the contact layer from a surface of the contact layer, extending into the portion of the first semiconductor layer sandwiched between the first base layer and the second base layer, and extending in the contact layer and the first semiconductor layer along the first direction, the conductor being electrically connected to the second electrode,
• the first insulating film covering an entire region of the first surface of the first semiconductor layer surrounded by the adjacent third base layers, the first base layer, and the second base layer,
• the second electrode being electrically connected onto the third emitter layer and the one of the third base layers on which the third emitter layer is formed,
• the first semiconductor layer including a barrier layer of the first conductivity type in the portion of the first semiconductor layer sandwiched between the first base layer and the second base layer, the barrier layer having a concentration of an impurity of the first conductivity type higher than a concentration of an impurity of the first conductivity type of the first semiconductor layer.