Semiconductor device

A semiconductor device, comprising:

• a semiconductor part including first to fourth semiconductor layers;
• a first electrode provided on a back surface of the semiconductor part;
• a second electrode provided on a front surface of the semiconductor part, the front surface being at a side opposite to the back surface;
• a third electrode provided in a first trench and extending into the semiconductor part from the front surface side of the semiconductor part;
• a first insulating film provided between the semiconductor part and the third electrode, the first insulating film electrically insulating the third electrode from the semiconductor part;
• a fourth electrode provided in a second trench and extending into the semiconductor part from the front surface side of the semiconductor part, the second trench provided at a position next to the first trench;
• and
• a second insulating film provided between the semiconductor part and the fourth electrode, the second insulating film electrically insulating the fourth electrode from the semiconductor part,
• the first semiconductor layer of a first conductivity type extending between the first electrode and the second electrode,
• the second semiconductor layer of a second conductivity type being provided between the first semiconductor layer and the second electrode and extending between the third electrode and the fourth electrode,
• the third semiconductor layer of the second conductivity type being partially provided on the second semiconductor layer between the second semiconductor layer and the second electrode, the third semiconductor layer including a second-conductivity-type impurity with a higher concentration than the second semiconductor layer,
• the fourth semiconductor layer of the first conductivity type being provided in the second semiconductor layer between the third electrode and the fourth electrode, the fourth semiconductor layer being apart from the third semiconductor layer, the second semiconductor layer extending between the third semiconductor layer and the fourth semiconductor layer,
• the second electrode being connected to the second and third semiconductor layers at the front surface of the semiconductor part, wherein
• the semiconductor part further includes fifth and sixth semiconductor layers,
• the fifth semiconductor layer of the first conductivity type being provided between the first semiconductor layer and the first electrode, the fifth semiconductor layer including a first-conductivity-type impurity with a higher concentration than a concentration of the first-conductivity-type impurity in the first semiconductor layer,
• the sixth semiconductor layer of the first conductivity type being partially provided on the second semiconductor layer between the second semiconductor layer and the second electrode,
• the third semiconductor layer and the sixth semiconductor layer are arranged on the second semiconductor layer and connected to the second electrode, and
• the third semiconductor layer is provided between the sixth semiconductor layer and the first insulating film in a first direction along the front surface of the semiconductor part.