Junction barrier Schottky (JBS) with floating islands

• US 7,671,439 B2
• Filed: 12/01/2006
• Issued: 03/02/2010
• 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
• Primary Examiner(s): Pert; Evan
• Assistant Examiner(s): AHMED, SELIM U
• Application Number:
  US11/607,583
• Publication Number:
  US 20070075392A1
• Time in Patent Office: 1,187 Days
• Field of Search: 257/483, 257/484, 257/478, 257/928, 257/471, 257/284, 257/E27.04, 257/E29.338, 257/E21.359, 257/E21.368, 257/E29.013, 438/570
• US Class Current: 257/471
• 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 plurality of trenches opened in a N-type semiconductor substrate with a Schottky barrier material disposed in said each plurality of trenches;

a plurality of P-type dopant regions disposed under said each plurality of trenches as floating islands in said semiconductor substrate as vertically implanted regions through said each plurality of trenches wherein each of said floating islands having a width substantially same or slightly broader than a width of said each plurality of trenches and substantially in vertical alignment with said each plurality of trenches.

2. The Schottky diode of claim 1 wherein:

said plurality of trenches opened in said N-type semiconductor substrate is filled with a Schottky barrier material composed of Ti/TiN or a tungsten metal disposed therein for constituting said Schottky barrier.

3. The Schottky diode of claim 1 wherein:

said plurality of trenches opened in said N-type semiconductor substrate is formed with a Schottky barrier material disposed on sidewalls of said plurality of trenches for constituting said Schottky barrier.

4. The Schottky diode of claim 1 further comprising:

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

5. The Schottky diode of claim 1 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 plurality of trenches.

6. The Schottky diode of claim 1 further comprising:

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

7. 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.

8. The Schottky diode of claim 7 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.

9. The Schottky diode of claim 1 further comprising:

a Schottky barrier material covering a top surface of said N-type semiconductor substrate constituting said Schottky barrier with said plurality of P-type dopant regions disposed below said each plurality of trenches filled with said Schottky barrier material and said P-type dopant regions implanted through said each plurality of trenches as floating islands functions as PN junctions with said N-type semiconductor substrate for preventing a leakage current generated from a reverse voltage.

10. A Schottky diode comprising:

a plurality of trenches opened in a P-type semiconductor substrate with a Schottky barrier material disposed in said each plurality of trenches;

a plurality of N-type dopant regions disposed under said each plurality of trenches as floating islands in said semiconductor substrate as vertically implanted regions through said each plurality of trenches wherein each of said floating islands having a width substantially same or slightly broader than a width of said each plurality of trenches and substantially in vertical alignment with said each plurality of trenches.

11. The Schottky diode of claim 10 wherein:

said plurality of trenches opened in said P-type semiconductor substrate is filled with a Schottky barrier material composed of Ti/TiN or a tungsten metal disposed in said plurality of trenches for constituting said Schottky barrier.

12. The Schottky diode of claim 10 wherein:

said plurality of trenches opened in said P-type semiconductor substrate is formed with a Schottky barrier material disposed on sidewalls of said plurality of trenches for constituting said Schottky barrier.

13. The Schottky diode of claim 10 further comprising:

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

14. The Schottky diode of claim 10 further comprising:

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

15. The Schottky diode of claim 10 wherein:

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

16. The Schottky diode of claim 10 further comprising:

a dialectical layer disposed along sidewalls of said plurality of trenches.