Thick field oxide termination for trench schottky device and process for manufacture

• US 20050062124A1
• Filed: 09/08/2004
• Published: 03/24/2005
• 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
• Granted Patent: US 7,973,381 B2
• Time in Patent Office: Days
• US Class Current: 257/476
• 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 at least one sidewall and a bottom wall; and

a second insulation layer of a second thickness disposed in said termination trench;

wherein said second thickness is thicker than said first thickness.

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 and a 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, and a contact layer 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 at least one sidewall of said termination trench and at least a portion of said bottom of said termination trench.

12. A schottky diode according to claim 1, wherein said termination trench includes another wall opposite said at least one sidewall, wherein said second insulation layer is disposed over said at least one sidewall, said bottom and said another sidewall of said termination trench.

13. A schottky diode according to claim 1, wherein said semiconductor body is epitaxial silicon.

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

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

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

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

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