Thick field oxide termination for trench schottky device

• US 7,973,381 B2
• Filed: 09/08/2004
• Issued: 07/05/2011
• Est. Priority Date: 09/08/2003
• Status: Active Grant

• Current Assignee: Infineon Technologies Americas Corp. (Infineon Technologies AG)
• Original Assignee: International Rectifier Corporation (Infineon Technologies AG)
• Inventors: Chiola, Davide
• Primary Examiner(s): Le; Thao X
• Assistant Examiner(s): Kraig; William F
• Application Number:
  US10/936,162
• Publication Number:
  US 20050062124A1
• Time in Patent Office: 2,491 Days
• Field of Search: 257/E21.359, 257/E29.338, 257/E29.359, 257471-486, 257/E33.051, 257/E29.013, 438/534, 438/570
• US Class Current: 257/483
• CPC Class Codes: H01L 29/0661 specially adapted for altering the breakdown voltage by removing semiconductor material at, or in the neighbourhood of, a reverse biased junction, e.g. by bevelling, moat etching, depletion etching
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/66143 Schottky diodes
• CPC Class Codes: H01L 29/872 Schottky diodes
• CPC Class Codes: H01L 29/8725 of the trench MOS barrier type [TMBS]

Abstract

A schottky diode of the trench variety which includes a trench termination having a thick insulation layer that is thicker than the insulation layer inside the trenches in its active region.

Claims

1. A Schottky diode comprising:

a semiconductor body of one conductivity said semiconductor body including an active region and a termination region;

a plurality of spaced trenches in said active region, each having opposing sidewalls and a bottom;

a first insulation layer of a first thickness on said sidewalls and said bottom of each of said trenches;

a semiconductor mesa disposed between each pair of spaced trenches;

a termination trench formed in said termination region, said termination trench including a first sidewall, a bottom wall, and another sidewall opposite said first sidewall;

an insulation layer disposed on said first sidewall, said bottom wall, and said another sidewall of said termination trench;

a conductive body having an inner surface disposed adjacent said insulation layer on said first sidewall and said bottom wall of said termination trench, said conductive body including an outer surface opposite said inner surface thereof;

a second insulation layer of a second thickness disposed in said termination trench and at least over said insulation layer in said termination trench; and

a contact layer extending from said active region into said termination trench and disposed over said second insulation layer on said conductive body adjacent said first sidewall of said termination trench and terminating within said termination trench over said bottom wall of said termination trench so as not to extend over said another sidewall;

wherein said second thickness is thicker than said first thickness;

wherein said second insulation layer is disposed over and covers the entire outer surface of said conductive body, wherein said insulation layer disposed over said bottom wall of said termination trench extends beyond said conductive body and under said second insulation layer, spacing said second insulation layer from said bottom wall of said termination trench along the entire length of said bottom wall of said termination trench; and

wherein said second insulation layer extends over the entire bottom wall and along said another sidewall of said termination trench.

2. A Schottky diode according to claim 1, further comprising a conductive body disposed inside each of said spaced trenches.

3. A Schottky diode according to claim 2, wherein said conductive body is comprised of polysilicon.

4. A Schottky diode according to claim 3, wherein said polysilicon is of another conductivity.

5. A Schottky diode according to claim 4, wherein said another conductivity is P type.

6. A Schottky diode according to claim 1, further comprising a Schottky metal layer in Schottky contact with said mesas.

7. A Schottky diode according to claim 6, further comprising an interlayer formed over said Schottky layer, said contact layer formed over said interlayer.

8. A Schottky diode according to claim 6, wherein said Schottky metal layer is comprised of palladium.

9. A Schottky diode according to claim 8, further comprising a molybdenum interlayer disposed over said Schottky, metal layer, wherein said contact layer is formed over said molybdenum interlayer.

10. A Schottky diode according to claim 9, wherein said contact layer is comprised of either aluminum or aluminum silicon.

11. A Schottky diode according to claim 7, wherein said Schottky metal layer, said interlayer and said contact layer extend over said first sidewall of said termination trench and at least a portion of said bottom wall of said termination trench.

12. A Schottky diode according to claim 1, wherein said semiconductor body is epitaxial silicon.

13. A Schottky diode according to claim 1, wherein said first conductivity is N-type.

14. A Schottky diode according to claim 1, wherein said first insulation layer is 4000 angstroms thick.

15. A Schottky diode according to claim 1, wherein said second insulation layer is 7000 angstroms thick.

16. A Schottky diode according to claim 1, wherein said second insulation layer is comprised of TEOS.

17. A Schottky diode according to claim 1, wherein said first insulation layer is comprised of silicon dioxide.

18. A Schottky diode according to claim 1, further comprising a second conductive body disposed between said second insulation layer and said insulation layer and extending along said another sidewall of said termination trench.