Trench junction barrier controlled Schottky device with top and bottom doped regions for enhancing forward current in a vertical direction

• US 7,737,522 B2
• Filed: 09/30/2006
• Issued: 06/15/2010
• Est. Priority Date: 02/11/2005
• Status: Active Grant

• Current Assignee: Alpha & Omega Semiconductor, Ltd.
• Original Assignee: Alpha & Omega Semiconductor, Ltd.
• Inventors: Bhalla, Anup, Lui, Sik K
• Primary Examiner(s): Pizarro; Marcos D
• Assistant Examiner(s): GUPTA, RAJ R
• Application Number:
  US11/541,189
• Publication Number:
  US 20070034901A1
• Time in Patent Office: 1,354 Days
• Field of Search: 257/287, 257471-486, 257/E21.359, 257/E27.04, 257/E29.013, 257/E29.148, 257/E29.262, 257/E29.338, 257/E33.051
• US Class Current: 257/472
• 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 29/66143 Schottky diodes
• 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
• CPC Class Codes: H01L 29/8725 of the trench MOS barrier type [TMBS]

Abstract

A Schottky diode includes at least a trenched opened in a semiconductor substrate doped with a dopant of a first conductivity type wherein the trench is filled with a Schottky junction barrier metal. The Schottky diode further includes one or more dopant region of a second conductivity type surrounding sidewalls of the trench distributed along the depth of the trench for shielding a reverse leakage current through the sidewalls of the trench. The Schottky diode further includes a bottom-doped region of the second conductivity type surrounding a bottom surface of the trench and a top-doped region of the second conductivity type surrounding a top portion of the sidewalls of the trench. In a preferred embodiment, the first conductivity type is a N-type conductivity type and the middle-depth dopant region comprising a P-dopant region.

Claims

1. A Schottky diode comprising:

at least a trench opened in a semiconductor substrate doped with a dopant of a first conductivity type wherein a sidewall of said trench is lined with a Schottky barrier metal;

a top doped region of a second conductivity type surrounding a top portion of said sidewalls of said trench to function as a reverse current shield for said Schottky diode; and

a bottom doped region of said second conductivity type surrounding all bottom corners of said trench and extending over a substantial area below a bottom surface of said trench with substantial areas along sidewalls of said trench lined with said Schottky barrier metal directly contacting said semiconductor substrate doped with said first conductivity type for enhancing a forward current passing therethrough in a vertical direction along said trench.

2. The Schottky diode of claim 1 further comprising:

one or more dopant regions of said second conductivity type surrounding sidewalls of said trench distributed along a depth of said trench between said top doped region and said bottom doped region to function as additional reverse current shields for said Schottky diode while still leaving substantial open areas not surrounded by said dopant regions of said second conductivity type along said sidewalls of said trench lined with said Schottky barrier metal directly contacting said semiconductor substrate doped with said first conductivity type for enhancing a forward current passing therethrough in a vertical direction along said trench.

3. The Schottky diode of claim 1 wherein:

said trench is filled with said Schottky barrier metal.

4. The Schottky diode of claim 1 wherein:

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

5. The Schottky diode of claim 1 wherein:

said bottom doped region of said second conductivity type completely surrounding a bottom surface of said trench.

6. The Schottky diode of claim 1 wherein:

said Schottky barrier metal overlaying a top surface of said semiconductor substrate forming a Schottky junction with said semiconductor substrate in a area between said top doped regions of second conductivity type.

7. The Schottky diode of claim 1 wherein:

said top doped regions of second conductivity type completely filling a space between said trenches.

8. The Schottky diode of claim 1 wherein:

said trench comprising non-rounded trench corners.

9. A semiconductor device comprising a Schottky diode comprising a trench disposed-on a semiconductor substrate of a first conductivity type, wherein said semiconductor device further comprising:

a top doped region of a second conductivity type opposite to said first conductivity type surrounding a top portion of sidewalls of said trench to function as a reverse current shield for said Schottky diode;

a bottom doped region of said second conductivity type surrounding a bottom portion of said trench; and

said sidewalls of said trench are lined with a Schottky barrier metal having a substantial areas between said top and bottom doped region directly contacting said semiconductor substrate doped with said first conductivity type for enhancing a forward current passing therethrough in a vertical direction along said trench.

10. The semiconductor device of claim 9 further comprising:

one or more dopant regions of said second conductivity type along said sidewalls distributed along a depth between said top doped region and said bottom doped region to function as additional reverse current shields for said Schottky diode while still leaving substantial open areas not surrounded by said dopant regions of said second conductivity type along said sidewalls of said trench lined with said Schottky barrier metal directly contacting said semiconductor substrate doped with said first conductivity type for enhancing a forward current passing therethrough in a vertical direction along said trench.

11. The semiconductor device claim 9 wherein:

said Schottky barrier metal completely lining said sidewalls of said trench.

12. The semiconductor device claim 9 wherein:

said top doped region of said second conductivity type formed at a top corner between said sidewalls of said trench and a top surface of said semiconductor substrate.

13. The semiconductor device claim 9 wherein:

said bottom doped region of said second conductivity type surrounding all bottom corners of said trench and extending over a substantial area below a bottom surface of said trench.

14. The semiconductor device claim 9 wherein:

said Schottky barrier metal overlaying a top surface of said semiconductor substrate forming a Schottky junction in an area between said top doped regions of second conductivity type.

15. The semiconductor device claim 9 wherein:

said top doped regions of second conductivity type extending allover a top surface said semiconductor substrate.

16. The semiconductor device claim 9 wherein:

said trench comprises non-rounded bottom corners.

17. The semiconductor device claim 9 further comprising:

a MOSFET device integrated with said Schottky diode configured as a trench junction barrier Schottky (TJBS) diode.

18. The semiconductor device of claim 9 further comprising:

a MOSFET device integrated with and manufactured simultaneously with said Schottky diode configured as a trench junction barrier Schottky (TJBS) diode.

19. The semiconductor device claim 9 further comprising:

a planar MOSFET device integrated and manufactured simultaneously with said Schottky diode wherein said planar MOSFET further comprising a body region extending to and constituting said top doped region of said second conductivity type surrounding a top portion of said trench of said Schottky diode for shielding a reverse leakage current through said sidewalls of said trench.

20. The semiconductor device claim 9 further comprising:

a trench MOSFET device integrated and manufactured simultaneously with said Schottky diode configured as a trench junction barrier Schottky (TJBS) diode wherein said trench MOSFET further comprising trenched gates disposing around said trench of said TJBS diode.

21. The semiconductor device claim 20 wherein:

said MOSFET device further comprising a body region extending to and constituting said top doped region of said second conductivity type surrounding a top portion of said trench of said Schottky diode for shielding said reverse leakage current through said sidewalls of said trench.