Semiconductor device and method of manufacturing semiconductor device

1. A semiconductor device, comprising:

a semiconductor substrate of a first conductivity type;

a first semiconductor layer of the first conductivity type, provided on a front surface of the semiconductor substrate, the first semiconductor layer having an impurity concentration that is lower than that of the semiconductor substrate;

a second semiconductor layer of a second conductivity type, selectively provided in a surface layer of the first semiconductor layer on a first side of the first semiconductor layer, opposite a second side of the first semiconductor layer facing toward the semiconductor substrate;

a first semiconductor region of the first conductivity type, selectively provided in a surface layer of the second semiconductor layer on a first side of the second semiconductor layer, opposite a second side of the second semiconductor layer facing toward the semiconductor substrate;

a second semiconductor region of the second conductivity type, selectively provided in the surface layer of the second semiconductor layer on the first side of the second semiconductor layer, the second semiconductor region having an impurity concentration that is higher than that of the second semiconductor layer;

a gate electrode provided, via a gate insulating film, at least at a part of a surface of the second semiconductor layer sandwiched between the first semiconductor region and the first semiconductor layer;

a first electrode provided on surfaces of the first semiconductor region and the second semiconductor layer;

a second electrode provided on a rear surface of the semiconductor substrate; and

a gate electrode pad electrically connected with the gate electrode,

wherein

a lifetime killer region, in which a lifetime killer is introduced, is provided at an interface of the second semiconductor layer and the first semiconductor layer, the lifetime killer region being provided at least partially in a portion of the second semiconductor layer disposed below the gate electrode pad and being excluded from the second semiconductor layer disposed below the first semiconductor region.

2. The semiconductor device according to claim 1 , wherein

the second semiconductor layer is provided below the gate electrode pad and the second semiconductor region is not provided below the gate electrode pad, and

an impurity concentration of the second semiconductor layer is at least 10 times lower than that of the second semiconductor region.

3. The semiconductor device according to claim 1 , further comprising a third semiconductor layer of the second conductivity type, selectively provided below the gate electrode pad, the third semiconductor layer being provided in the surface layer of the first semiconductor layer on the first side of the first semiconductor layer, the third semiconductor layer having an impurity concentration that is at least 10 times lower than that of the second semiconductor region, and

the third semiconductor layer is thinner than the second semiconductor layer.

4. The semiconductor device according to claim 3 , wherein

the third semiconductor layer has a depth equal to that of the second semiconductor region in an active region in which main current flows during an ON state, the third semiconductor layer surrounding the gate electrode pad.

5. The semiconductor device according to claim 1 , wherein

the first semiconductor layer is provided under the gate electrode pad.

6. The semiconductor device according to claim 1 , wherein,

in an active region in which main current flows during an ON state, a first region is not used as a main element, and

the lifetime killer region is provided at least partially in a portion of the second semiconductor layer disposed in a second region opposing the first region in the depth direction.

7. The semiconductor device according to claim 6 , wherein

the first region includes a current sensor pad part, a temperature sensor pad part and an arithmetic circuit part.

8. The semiconductor device according to claim 1 , wherein

the lifetime killer region is provided so as to overlap, in a depth direction, an entirety of the second semiconductor layer disposed below the gate electrode pad.

9. The semiconductor device according to claim 1 , wherein

the lifetime killer includes gold or platinum.

10. A method of manufacturing a semiconductor device, the method comprising:

forming a first semiconductor layer of a first conductivity type on a front surface of a semiconductor substrate of the first conductivity type, the first semiconductor layer having an impurity concentration that is lower than that of the semiconductor substrate;

selectively forming a second semiconductor layer of a second conductivity type in a surface layer of the first semiconductor layer on a first side of the first semiconductor layer, opposite a second side of the first semiconductor layer facing toward the semiconductor substrate;

selectively forming a first semiconductor region of the first conductivity type in a surface layer of the second semiconductor layer on a first side of the second semiconductor layer, opposite a second side of the second semiconductor layer facing toward the semiconductor substrate;

selectively forming a second semiconductor region of the second conductivity type in the surface layer of the second semiconductor layer on the first side of the second semiconductor layer, the second semiconductor region having an impurity concentration that is higher than that of the second semiconductor layer;

introducing a lifetime killer to form a lifetime killer region which is provided at an interface of the second semiconductor layer and the first semiconductor layer;

forming, via a gate insulating film, a gate electrode at least at a part of a surface of the second semiconductor layer sandwiched between the first semiconductor region and the first semiconductor layer;

forming a first electrode on surfaces of the first semiconductor region and the second semiconductor layer;

forming a second electrode on a rear surface of the semiconductor substrate; and

forming a gate electrode pad electrically connected with the gate electrode,

wherein

the lifetime killer region is provided at least partially in a portion of the second semiconductor layer disposed below the gate electrode pad and is excluded from the second semiconductor layer disposed below the first semiconductor region.