Semiconductor device

1. A semiconductor device comprising:

a first semiconductor region of a first conductivity type;

a second semiconductor region of a second conductivity type on the first semiconductor region;

a third semiconductor region of the first conductivity type on the second semiconductor region;

a first electrode surrounded by the first semiconductor region;

a gate electrode above the first electrode;

a gate insulating portion between the second semiconductor region and the gate electrode;

a first insulating portion in contact with a first part of the first electrode and between the first part of the first electrode and the first semiconductor region; and

a second insulating portion having a higher dielectric constant than the first insulating portion and the same dielectric constant as the gate insulating portion, in contact with a second part of the first electrode and between the second part of the first electrode and the first semiconductor region, the second part of the first electrode located closer to the gate electrode than the first part of the first electrode.

2. The semiconductor device according to claim 1 , wherein

the first insulating portion is an air gap.

3. The semiconductor device according to claim 2 , wherein

the first insulating portion includes a first insulating layer between the first semiconductor region and the air gap and a second insulating layer between the first part of the first electrode and the air gap.

4. The semiconductor device according to claim 2 , wherein

the first insulating portion includes an insulating layer in contact with the first semiconductor region and a lower surface of the first part of the first electrode.

5. The semiconductor device according to claim 1 , wherein

the first insulating portion includes an insulating layer in contact with the first part of the first electrode and the first semiconductor region such that there is no air gap between the first part of the first electrode and the first semiconductor region.

6. The semiconductor device according to claim 5 , wherein

the second insulating portion electrically isolates the first electrode from the gate electrode.

7. The semiconductor device according to claim 1 , wherein

the first part is longer in a direction toward the gate electrode than the second part.

8. The semiconductor device according to claim 1 , wherein

the gate electrode extends in a first direction and the first electrode includes a first portion that extends in the first direction below the gate electrode and a second portion that extends in a second direction to be higher than an upper end of the first portion.

9. The semiconductor device according to claim 8 , wherein

the gate electrode is connected to the first portion of the first electrode.

10. The semiconductor device according to claim 8 , wherein the second portion is aligned with the gate electrode along the first direction.

11. The semiconductor device according to claim 8 , wherein the second portion is not aligned with the gate electrode along the first direction.

12. A semiconductor device comprising:

a drain electrode;

a drain region electrically coupled to the drain electrode;

a first semiconductor region on the drain region;

a second semiconductor region on the first semiconductor region;

a contact region and a source region, each selectively provided on the second semiconductor region;

a source electrode electrically coupled to the contact region and the source region;

a field plate electrode surrounded by the first semiconductor region and separated from the first semiconductor region by first and second insulating portions, the first insulating portion located closer to the drain region and having a lower dielectric constant than the second insulating portion;

a gate electrode above the field plate electrode and electrically isolated from the source electrode; and

a gate insulating portion, between the second semiconductor region and the gate electrode, and having the same dielectric constant as the second insulating portion.

13. The semiconductor device according to claim 12 , wherein

the first insulating portion is an air gap.

14. The semiconductor device according to claim 13 , wherein

the first insulating portion includes a first insulating layer between the first semiconductor region and the air gap and a second insulating layer between the field plate electrode and the air gap.

15. The semiconductor device according to claim 13 , wherein

the first insulating portion includes an insulating layer in contact with the first semiconductor region and a lower surface of the field plate electrode.

16. The semiconductor device according to claim 12 , wherein

the second insulating portion electrically isolates the field plate electrode from the gate electrode.

17. The semiconductor device according to claim 12 , wherein

the gate electrode extends in a first direction and the field plate electrode includes a first portion that extends in the first direction below the gate electrode and a second portion that extends in a second direction to be higher than an upper end of the first portion.

18. The semiconductor device according to claim 17 , wherein

the gate electrode is connected to the field plate electrode.

19. The semiconductor device according to claim 17 , wherein the second portion is aligned with the gate electrode along the first direction.

20. The semiconductor device according to claim 17 , wherein the second portion is not aligned with the gate electrode along the first direction.

21. The semiconductor device according to claim 12 , wherein

the first insulating portion includes an insulating layer in contact with the field plate electrode and the first semiconductor region such that there is no air gap between the field plate electrode and the first semiconductor region.