ACCUFET with Schottky source contact

• US 7,485,932 B2
• Filed: 07/20/2005
• Issued: 02/03/2009
• Est. Priority Date: 07/20/2004
• Status: Active Grant

• Current Assignee: Infineon Technologies Americas Corp. (Infineon Technologies AG)
• Original Assignee: International Rectifier Corporation (Infineon Technologies AG)
• Inventors: Thapar, Naresh
• Primary Examiner(s): SEFER, AHMED N
• Application Number:
  US11/185,319
• Publication Number:
  US 20060017078A1
• Time in Patent Office: 1,294 Days
• Field of Search: 257/213, 257/284, 257330-332, 257/336, 257/369
• US Class Current: 257/369
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/41766 with at least part of the source or drain electrode having contact below the semiconductor surface, e.g. the source or drain electrode formed at least partially in a groove or with inclusions of conductor inside the semiconductor H01L29/41733 - H01L29/41758 take precedence
• CPC Class Codes: H01L 29/7828 without inversion channel, e.g. vertical ACCUFETs, normally-on vertical MISFETs
• CPC Class Codes: H01L 29/7839 with Schottky drain or source contact

Abstract

An accumulation mode FET (ACCUFET) which includes an insulated gate, an adjacently disposed insulated source field electrode, and a source contact that makes Schottky contact with the base region of the ACCUFET.

Claims

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.