MOSgated power semiconductor device with source field electrode

1. A power semiconductor device comprising:

a semiconductor body having a common conduction region of one conductivity type, and a base region of another conductivity type, said semiconductor body including a first surface;

a trench extending from said first surface through said base region and into said common conduction region, said trench including at least two opposing sidewalls and a bottom;

an insulated gate electrode including both a gate insulation adjacent one of said sidewalls and a gate electrode adjacent said gate insulation which spans said base region;

a source field electrode inside said trench, said source field electrode including a first portion spanning said gate electrode and a second portion extending to a depth below said insulated gate electrode;

a source region adjacent a sidewall of said trench and said base region; and

a source contact ohmically coupled to said source region, wherein said source contact is in direct ohmic contact with at least a portion of a sidewall of said source field electrode that is parallel to said trench sidewalls.

2. A semiconductor device according to claim 1 , wherein said source contact is ohmically coupled to a portion of a top surface of said source field electrode.

3. A semiconductor device according to claim 1 , further comprising a bottom insulation body disposed between said second portion of said source field electrode and said sidewalls and said bottom of said trench.

4. A semiconductor device according to claim 3 , wherein said bottom insulation body is thicker than said gate insulation.

5. A semiconductor device according to claim 3 , wherein said bottom insulation body includes a first portion disposed below said gate electrode and a second portion opposite said first portion having a recess formed therein and another electrode formed in said recess ohmically coupled to said source contact.

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

7. A semiconductor device according to claim 1 , wherein said gate electrode is comprised of conductive polysilicon.

8. A semiconductor device according to claim 1 , wherein said semiconductor body is comprised of epitaxial silicon.

9. A semiconductor device according to claim 8 , wherein said epitaxial silicon is formed over a silicon substrate, and further comprising a drain contact ohmically connected to said silicon substrate.

10. The semiconductor device of claim 1 , further comprising a second insulated gate electrode including both a second gate insulation adjacent the opposite sidewall of said trench and a second gate electrode adjacent said second gate insulation which spans said base region.

11. A power semiconductor device comprising:

a semiconductor body including a top surface;

a trench extending from said top surface into said semiconductor body, wherein a gate electrode and a single source field electrode are disposed within said trench;

a gate insulation interposed between a sidewall of said trench and said gate electrode;

said source field electrode disposed between said gate electrode and an opposite sidewall of said trench, and said source field electrode extending below said gate electrode; and

a source contact coupled to said source field electrode at a portion of a sidewall of said source field electrode substantially parallel to said sidewall.

12. The semiconductor device of claim 11 , wherein said source contact is ohmically coupled to a portion of a top surface of said source field electrode.

13. The semiconductor device of claim 11 , further comprising a bottom insulation body disposed between the portion of said source field electrode extending below said gate electrode and said sidewalls and a bottom of said trench.

14. The semiconductor device of claim 13 , wherein said bottom insulation body is thicker than said gate insulation.

15. The semiconductor device of claim 13 , wherein said bottom insulation body includes a first portion disposed below said gate electrode and a second portion opposite said first portion having a recess formed therein and another gate electrode formed in said recess coupled to said source contact.

16. The semiconductor device of claim 11 , wherein said source field electrode is comprised of conductive polysilicon.

17. The semiconductor device of claim 11 , wherein said gate electrode is comprised of conductive polysilicon.

18. The semiconductor device of claim 11 , wherein said semiconductor body comprises epitaxial silicon.

19. The semiconductor device of claim 18 , wherein said epitaxial silicon is formed over a silicon substrate, and further comprising a drain contact ohmically connected to said silicon substrate.

20. The semiconductor device of claim 11 , further comprising a second gate electrode disposed within said trench and a gate insulation interposed between said opposite sidewall and said second gate electrode.