Junction barrier schottky (JBS) with floating islands

• US 20070075392A1
• Filed: 12/01/2006
• Published: 04/05/2007
• Est. Priority Date: 02/11/2005
• Status: Active Grant

• Current Assignee: Alpha & Omega Semiconductor, Ltd.
• Original Assignee: Alpha & Omega Semiconductor, Ltd.
• Inventors: Bhalla, Anup, Pan, Ji
• Granted Patent: US 7,671,439 B2
• Time in Patent Office: Days
• US Class Current: 257/483
• CPC Class Codes: H01L 29/0623 Buried supplementary region, e.g. buried guard ring multi-RESURF H01L29/0634
• CPC Class Codes: H01L 29/1095 Body region, i.e. base region, of DMOS transistors or IGBTs cell layout H01L29/0696
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• 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 29/7811 with an edge termination structure guard regions per se H01L29/0619; field plates per se H01L29/402
• CPC Class Codes: H01L 29/782 the other device being a Schottky barrier diode

Abstract

A Schottky diode includes a Schottky barrier and a plurality of dopant regions disposed near the Schottky barrier as floating islands to function as PN junctions for preventing a leakage current generated from a reverse voltage. At least a trench opened in a semiconductor substrate with a Schottky barrier material disposed therein constitutes the Schottky barrier. The Schottky barrier material may also be disposed on sidewalls of the trench for constituting the Schottky barrier. The trench may be filled with the Schottky barrier material composed of Ti/TiN or a tungsten metal disposed therein for constituting the Schottky barrier. The trench is opened in a N-type semiconductor substrate and the dopant regions includes P-doped regions disposed under the trench constitute the floating islands. The P-doped floating islands may be formed as vertical arrays under the bottom of the trench.

Claims

1. A Schottky diode comprising:

a Schottky barrier and a plurality of dopant regions disposed near said Schottky barrier as floating islands to function as PN junctions for preventing a leakage current generated from a reverse voltage.

2. The Schottky diode of claim 1 further comprising:

at least a trench opened in a semiconductor substrate with a Schottky barrier material disposed therein for constituting said Schottky barrier.

3. The Schottky diode of claim 1 further comprising:

at least a trench opened in a semiconductor substrate with a Schottky barrier material composed of Ti/TiN or a tungsten metal disposed therein for constituting said Schottky barrier.

4. The Schottky diode of claim 1 further comprising:

at least a trench opened in a semiconductor substrate with a Schottky barrier material disposed on sidewalls of said trench for constituting said Schottky barrier.

5. The Schottky diode of claim 1 further comprising:

at least a trench opened in a N-type semiconductor substrate with a Schottky barrier material disposed in said trench for constituting said Schottky barrier; and

said plurality of dopant regions comprising P-doped regions disposed under said trench constituting floating islands.

6. The Schottky diode of claim 5 wherein:

said plurality of dopant regions comprising P-doped regions disposed as an vertical array of floating islands under said trench constituting floating islands.

7. The Schottky diode of claim 2 further comprising:

a contact metal covering and contacting said Schottky barrier disposed in said trench to function as an electrode for said Schottky diode.

8. The Schottky diode of claim 2 further comprising:

a bottom doped region of a second conductivity type in said semiconductor substrate of a first conductivity type surrounding at least a bottom corner of said trench.

9. The Schottky diode of claim 2 further comprising:

a top doped region of a second conductivity type surrounding a top portion of sidewalls of said trench in said semiconductor substrate of a first conductivity type.

10. The Schottky diode of claim 2 further comprising:

one or more dopant regions of a second conductivity type surrounding sidewalls of said trench distributed along a depth of said trench in said semiconductor substrate of a first conductivity type.

11. The Schottky diode of claim 2 wherein:

said Schottky barrier metal further lining a bottom surface of said trench forming a Schottky junction on said trench bottom surface.

12. The Schottky diode of claim 2 further comprising:

a dialectical layer disposed along sidewalls of said;

trench.

13. The Schottky diode of claim 2 further comprising:

a conductive material composed of doped polysilicon filling said trench and said Schottky barrier comprising a Schottky barrier layer disposed on top of said trench contacting said doped polysilicon.

14. The Schottky diode of claim 1 further comprising:

a shallow trench filled with a Schottky barrier material for constituting said Schottky barrier wherein said shallow trench is surrounded by a doped region of a second conductivity type in a semiconductor substrate of a first conductivity type wherein said shallow trench having rounded trench-bottom corners.

15. The Schottky diode of claim 14 further comprising:

a dielectric layer insulating said doped region of a second conductivity type whereby said doped region of said second conductivity type is prevented from contacting a trench corner and is contacting only said Schottky barrier material filling said shallow trench.

16. The Schottky diode of claim 1 further comprising:

a Schottky barrier material covering a top surface of a semiconductor substrate constituting said Schottky barrier with said plurality of dopant regions disposed below said Schottky barrier material as floating islands to function as PN junctions for preventing a leakage current generated from a reverse voltage.

17. A method for manufacturing a Schottky diode comprising:

forming a plurality of dopant regions followed by forming a Schottky barrier near said dopant regions as floating islands to function as PN junctions for preventing a leakage current generated from a reverse voltage applied to said Schottky barrier.

18. The method of claim 17 further comprising:

opening at least a trench in a semiconductor substrate followed by implanting dopant ions through said trench to form said dopant regions below a bottom surface of said trench; and

filling a Schottky barrier material therein to form said Schottky barrier in said trench.

19. The method of claim 18 wherein:

said step of filling said Schottky barrier material further comprising a step of filling Ti/TiN or a tungsten metal into said trench for forming said Schottky barrier.

20. The method of claim 18 wherein:

said step of filling said Schottky barrier material further comprising a step of disposing a Schottky barrier material on sidewalls of said trench to form said Schottky barrier along sidewalls of said trench.

21. A Schottky diode comprising:

a Schottky barrier and a plurality of regions disposed near said Schottky barrier to function as PN junctions for distributing a reverse bias voltage over said PN junctions and said Schottky barrier for reducing a leakage current generated from said reverse bias voltage.