Integrated MOSFET and Schottky device

• US 8,101,995 B2
• Filed: 02/08/2008
• Issued: 01/24/2012
• Est. Priority Date: 02/08/2007
• Status: Active Grant

• Current Assignee: Infineon Technologies Americas Corp. (Infineon Technologies AG)
• Original Assignee: International Rectifier Corporation (Infineon Technologies AG)
• Inventors: Henson, Timothy, Girdhar, Dev Alok
• Primary Examiner(s): Pizarro Crespo, Marcos D
• Assistant Examiner(s): TANG, SUIAN
• Application Number:
  US12/028,239
• Publication Number:
  US 20080191274A1
• Time in Patent Office: 1,446 Days
• Field of Search: 257/288, 257/330, 257/401, 257/901, 257/E29, 257135-136, 257/242, 257/329, 257/E27, 257/260, 438292-308, 438/136, 438/137, 438/156, 438/173, 438/192, 438/206, 438/212, 438/257, 438/E21
• US Class Current: 257/333
• 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 29/42368 the thickness being non-uniform
• CPC Class Codes: H01L 29/456 on silicon
• CPC Class Codes: H01L 29/66727 with a step of recessing the source electrode
• CPC Class Codes: H01L 29/66734 with a step of recessing the gate electrode, e.g. to form a trench gate electrode
• CPC Class Codes: H01L 29/7806 the other device being a Schottky barrier diode
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236

Abstract

A power semiconductor device that includes a trench power MOSFET with deep source field electrodes and an integrated Schottky diode.

Claims

1. A power semiconductor device comprising:

a semiconductor body of one conductivity;

a first source trench extending into said semiconductor body, and a second source trench extending into said semiconductor body, each said source trench including one sidewall adjacent a base region of another conductivity in said semiconductor body and another opposing sidewall adjacent a schottky region, and each said source trench further including a gate electrode spanning said base region, a gate oxide body, and a deep source field electrode that extends past said gate electrode to a depth below said gate electrode disposed within said source trench, said gate oxide body formed between said one sidewall and a side of said gate electrode facing said one sidewall, and said gate oxide body formed between said deep source field electrode and an opposite side of said gate electrode facing said deep source field electrode.

2. The power semiconductor device of claim 1, wherein each said source trench further includes another gate electrode spanning a portion of said schottky region and another gate oxide body, and wherein said deep source field electrode extends past said another gate electrode to a depth below said another gate electrode.

3. The power semiconductor device of claim 2, further comprising a source contact coupled to said deep source field electrodes and said another gate electrode.

4. The power semiconductor device of claim 1, wherein said schottky region comprises a mesa of only said one conductivity and includes a schottky barrier body formed at a top portion thereof.

5. The power semiconductor device of claim 1, wherein said schottky region comprises a mesa of only said one conductivity that makes schottky contact with a source contact of said device.

6. The power semiconductor device of claim 1, wherein each said deep source field electrode resides in a thick insulation body that is thicker than said gate oxide body therein residing below said gate electrode.

7. The power semiconductor device of claim 6, wherein said thick insulation body extends along said another sidewall in each said source trench to the top of said semiconductor body.

8. The power semiconductor device of claim 1, wherein said Schottky region includes one mesa.

9. The power semiconductor device of claim 1, wherein said Schottky region includes a plurality of adjacent Schottky mesas.

10. A power semiconductor device comprising:

a semiconductor body of one conductivity;

a plurality of source trenches extending into said semiconductor body, each said source trench including a gate electrode, a gate oxide body, and a deep source field electrode that extends past said gate electrode to a depth below said gate electrode disposed within said source trench, each said source trench further including one sidewall adjacent a first mesa in said semiconductor body and another opposing sidewall adjacent a second mesa in said semiconductor body;

said first mesa comprising a base region of another conductivity and said second mesa comprising a schottky mesa, each said source trench being spaced from an adjacent said source trench by said schottky mesa;

said gate oxide body in each said source trench being on respective facing sides of said deep source field electrode and said gate electrode.

11. The power semiconductor device of claim 10, wherein each said source trench is spaced from at least two said source trenches by a respective schottky mesa.

12. The power semiconductor device of claim 10, wherein said gate oxide body is also on a side of said gate electrode that faces said base region.

13. The power semiconductor device of claim 10, wherein said plurality of source trenches each further include a thick oxide body disposed within and lining at least a bottom and a portion of the sidewalls thereof, said gate electrode disposed over said thick oxide body.

14. The power semiconductor device of claim 10, wherein each said source trench further includes another gate electrode and another gate oxide body, and wherein said deep source field electrode is insulated from, but extending through said gate electrodes.

15. The power semiconductor device of claim 14, further comprising a source contact coupled to said deep source field electrode and said another gate electrode.

16. A power semiconductor device comprising:

a semiconductor body of one conductivity;

a source trench extending into said semiconductor body including one sidewall adjacent a base region of another conductivity in said semiconductor body and another opposing sidewall adjacent a schottky region;

said source trench further including a gate electrode spanning said base region, a gate oxide body, and a deep source field electrode that extends past said gate electrode to a depth below said gate electrode disposed within said source trench, said gate oxide body on respective facing sides of said deep source field electrode and said gate electrode.

17. The power semiconductor device of claim 16, comprising:

a source contact coupled to said deep source field electrode;

a schottky barrier metal body over said source trench and said schottky region, said schottky barrier metal body making schottky contact with said source contact.

18. The power semiconductor device of claim 16, wherein said source trench further includes a thick oxide body disposed within and lining at least a bottom and a portion of the sidewalls thereof, said gate electrode disposed over said thick oxide body.

19. The power semiconductor device of claim 16, wherein said source trench further includes another gate electrode and another gate oxide body, and wherein said deep source field electrode is insulated from, but extends through said gate electrode and said another gate electrode.

20. The power semiconductor device of claim 19, further comprising a source contact coupled to said deep source field electrode and said another gate electrode.