ACCUFET with Schottky source contact

1. An integrated MOSgated power semiconductor device comprising:

a drift region of one conductivity;

a base region of said one conductivity above said drift region;

a source region of said one conductivity above said base region;

a first insulated gate adjacent said base region;

a second insulated gate adjacent said base region;

an insulated source field electrode adjacent said drift region and laterally adjacent said first and second insulated gates, said insulated source field electrode including a source field electrode; and

a source contact making ohmic contact with said source region, said source field electrode, and Schottky contact with said base region; wherein said first insulated gate, said second insulated gate and said insulated source field electrode are disposed in a common trench.

2. A device according to claim 1 , further comprising a substrate of the same conductivity as said drift region, wherein said drift region is formed over said substrate.

3. A device according to claim 2 , further comprising a drain contact electrically connected to said substrate.

4. A device according to claim 1 , wherein said insulated source field electrode extends to a depth below that of said insulated gate electrode.

5. A device according to claim 1 , wherein said source field electrode is comprised of conductive polysilicon.

6. A device according to claim 1 , wherein said insulated gate includes a gate insulator, a gate electrode, and an insulation body at a bottom of said gate electrode, said gate insulator being interposed between said base region and said gate electrode, and said insulation body being thicker than said gate insulator.

7. A device according to claim 1 , further comprising a recess extending to a depth below said source region and terminating in said base region, wherein said source contact makes Schottky contact with said base region inside said recess.

8. A device according to claim 7 , wherein said recess is spaced from said insulated gate.

9. An integrated MOSgated power semiconductor device comprising:

an accumulation mode FET having an insulated gate, an insulated source field electrode laterally adjacent said insulated gate, a source contact and a base region;

a Schottky diode, said Schottky diode being formed by a Schottky contact between said source contact and said base region; and

another insulated gate, wherein said insulated gate, said another insulated gate and said insulated source field electrode are disposed in a common trench, and wherein said insulated source field electrode is disposed between said insulated gates, wherein said Schottkv diode and said accumulation mode FET share a drift region, and wherein said insulated source field electrode is adjacent said drift region.

10. A device according to claim 9 , wherein said insulated source field electrode and said insulated gate are disposed in a common trench.

11. A device according to claim 9 , further comprising a recess extending to a depth below said source region and terminating in said base region, wherein said source contact makes Schottky contact with said base region inside said recess.