Wide band gap semiconductor device with surface insulating film
A semiconductor device of the present invention includes a semiconductor layer of a first conductivity type having a cell portion and an outer peripheral portion disposed around the cell portion, and a surface insulating film disposed in a manner extending across the cell portion and the outer peripheral portion, and in the cell portion, formed to be thinner than a part in the outer peripheral portion.
1. A wide band gap semiconductor device comprising:
a semiconductor substrate;
a first gate insulating film on the semiconductor substrate;
a first gate electrode on the first gate insulating film;
a second gate insulating film on the semiconductor substrate; and
a second gate electrode on the second gate insulating film; and
a source electrode placed over the semiconductor substrate, the first gate electrode and the second gate electrode,
wherein a portion of a surface of the semiconductor substrate between a center of the first gate electrode and a center of the second gate electrode is recessed compared to a portion of a surface of the semiconductor substrate under the center of the first gate electrode and the center of the second gate electrode,
wherein the semiconductor substrate comprises an outer peripheral recessed portion that includes a recess, and
a part of the source electrode is arranged between the first and second gate electrodes and the recess of the outer peripheral recessed portion and does not intrude into the recess of the outer peripheral recessed portion in a cross section.
2. The wide band gap semiconductor device according to claim 1 , wherein a gate pad is placed in a vicinity of one side of the semiconductor substrate.
3. The wide band gap semiconductor device according to claim 2 , wherein the gate pad is placed in the middle of the one side of the semiconductor substrate.
4. The wide band gap semiconductor device according to claim 1 , wherein a source contact region is placed in a region between the first gate electrode and the second gate electrode.
5. The wide band gap semiconductor device according to claim 4 , wherein at least one of the first gate electrode and the second gate electrode is a planer type gate electrode.
6. The wide band gap semiconductor device according to claim 5 , wherein a gate finger is placed between the source electrode and the outer peripheral recessed portion of the semiconductor substrate in a cross section.
7. The wide band gap semiconductor device according to claim 6 , wherein a height of the gate finger is approximately the same as a height of the source electrode.
8. The wide band gap semiconductor device according to claim 7 , wherein the source electrode is made of a material including an aluminum.
9. The wide band gap semiconductor device according to claim 8 , wherein the gate finger is made of a material including an aluminum.
10. The wide band gap semiconductor device according to claim 9 , wherein a peripheral source electrode is placed between the gate finger and the outer peripheral recessed portion of the semiconductor substrate.
11. The wide band gap semiconductor device according to claim 10 , wherein the semiconductor substrate is made of SiC, GaN, or diamond.
12. The wide band gap semiconductor device according to claim 11 , further comprising a titanium material between the source electrode and the semiconductor substrate at the source contact region.
13. The wide band gap semiconductor device according to claim 12 , wherein the gate insulating film is made of a material including silicon.
14. The wide band gap semiconductor device according to claim 13 , wherein the gate electrode is made of a material including a polysilicon.
15. The wide band gap semiconductor device according to claim 14 , wherein a surface of the source electrode is dented according to the surface of the semiconductor substrate.
16. The wide band gap semiconductor device according to claim 14 , wherein a depth of the recess of the portion of the surface of the semiconductor substrate between the center of the first gate electrode and the center of the second gate electrode is approximately the same as a depth of the recess of the outer peripheral recessed portion.
17. The wide band gap semiconductor device according to claim 14 , wherein the recess of the portion of surface of the semiconductor substrate between the center of the first gate electrode and the center of the second gate electrode is fabricated at a same time with the recess of the outer peripheral recessed portion.
18. The wide band gap semiconductor device according to claim 14 , wherein an impurity region of P-type material is placed at a surface of the outer peripheral recessed portion.
19. The wide band gap semiconductor device according to claim 3 , wherein an aluminum wire is connected to the source electrode.
20. The wide band gap semiconductor device according to claim 19 , wherein a surface of the source electrode has an unevenness.
21. The wide band gap semiconductor device according to claim 20 , the unevenness is placed according to a shape of a covered object covered by the source electrode.