Semiconductor device

1. A semiconductor device, comprising:

a first semiconductor layer of a first conductivity type;

a second semiconductor layer of a second conductivity type provided in a portion on the first semiconductor layer;

a gate electrode provided inside the first semiconductor layer and the second semiconductor layer with a gate insulator film interposed between the gate electrode and the first semiconductor layer and between the gate electrode and the second semiconductor layer;

a first insulating layer provided on the first semiconductor layer on a terminal region side of the second semiconductor layer;

a third semiconductor layer of the second conductivity type provided on the first semiconductor layer on the terminal region side of the first insulating layer;

a second insulating layer provided on the first semiconductor layer on the terminal region side of the third semiconductor layer;

a fourth semiconductor layer of the first conductivity type provided between the first semiconductor layer and the second insulating layer;

an inter-layer insulating film provided on the first semiconductor layer to contact the second semiconductor layer, the third semiconductor layer, the first insulating layer, and the second insulating layer; and

a plurality of field plate electrodes provided inside the inter-layer insulating film, the plurality of field plate electrodes having mutually-different distances from the first semiconductor layer.

2. The device according to claim 1 , further comprising a fifth semiconductor layer of the first conductivity type provided between the first semiconductor layer and the first insulating layer.

3. The device according to claim 1 , wherein the fourth semiconductor layer covers the surfaces of the second insulating layer other than an upper surface of the second insulating layer.

4. The device according to claim 1 , further comprising a fourth semiconductor layer of the first conductivity type provided on the first semiconductor layer on the terminal region side of the fourth semiconductor layer.

5. A semiconductor device, comprising:

a first semiconductor layer of a first conductivity type;

a second semiconductor layer of a second conductivity type provided in a portion on the first semiconductor layer;

a gate electrode piercing the second semiconductor layer, a lower end of the gate electrode entering the first semiconductor layer;

a gate insulator film provided between the gate electrode and the first semiconductor layer and between the gate electrode and the second semiconductor layer;

a fourth semiconductor layer of the first conductivity type provided on the first semiconductor layer on a terminal region side of the second semiconductor layer;

a third semiconductor layer of the second conductivity type provided on the first semiconductor layer on the terminal region side of the fourth semiconductor layer;

a fifth semiconductor layer of the first conductivity type provided on the first semiconductor layer on the terminal region side of the third semiconductor layer;

a first insulating layer provided on the fourth semiconductor layer;

a second insulating layer provided on the fifth semiconductor layer;

an inter-layer insulating film provided on the first semiconductor layer to contact the second semiconductor layer, the third semiconductor layer, the fourth semiconductor layer, the fifth semiconductor layer, the first insulating layer, and the second insulating layer; and

a plurality of field plate electrodes provided inside the inter-layer insulating film, the plurality of field plate electrodes having mutually-different distances from the first semiconductor layer.

6. The device according to claim 5 , wherein the fourth semiconductor layer and the fifth semiconductor layer are formed by epitaxial growth.