Trench junction barrier controlled Schottky

• US 8,445,370 B2
• Filed: 06/14/2010
• Issued: 05/21/2013
• Est. Priority Date: 09/30/2006
• Status: Active Grant

• Current Assignee: Alpha & Omega Semiconductor, Ltd.
• Original Assignee: Alpha & Omega Semiconductor, Ltd.
• Inventors: Lui, Sik K, Bhalla, Anup
• Primary Examiner(s): Whalen, Daniel
• Assistant Examiner(s): Gupta, Raj R
• Application Number:
  US12/802,790
• Publication Number:
  US 20100258897A1
• Time in Patent Office: 1,072 Days
• Field of Search: 257471-486, 257/287, 257/E29.262, 257/E33.015, 257/E27.04, 257/E29.013, 257/E29.148, 257/E29.338, 257/E21.359, 438/582
• US Class Current: 438/582
• 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 method for manufacturing a Schottky diode comprising steps of 1) providing a region with a dopant of a second conductivity type opposite to a first conductivity type to form a top doped region in a semiconductor substrate of said first conductivity type; 2) providing a trench through the top doped region to a predetermined depth and providing a dopant of the second conductivity type to form a bottom dopant region of the second conductivity type; and 3) lining a Schottky barrier metal layer on a sidewall of the trench at least extending from a bottom of the top doped region to a top of the bottom doped region.

Claims

1. A method for manufacturing a Schottky diode comprising:

applying a first mask on a semiconductor substrate of a first conductivity type to implant a plurality of top dopant regions of a second conductivity type below a top surface of the semiconductor substrate;

applying a second mask to open a plurality of trenches in areas surrounded by the top dopant region wherein said top dopant regions surrounding top sidewalls of the trenches;

implanting trench bottom dopant regions of the second conductivity type through the trenches and diffusing the trench bottom dopant regions wherein said trench dopant regions surrounding all bottom corners of said trenches and extending over a substantial area below a bottom surface of said trenches with substantial areas along bottom sidewalls of said trenches; and

lining a Schottky barrier metal layer on sidewalls of said trenches wherein the top doped region wherein the top dopant regions surrounding the Schottky barrier metal layer on the top sidewalls; and

the trench bottom dopant regions surrounding the Schottky barrier metal layer on the bottom sidewalls and the trench bottom surface.

2. The method of claim 1 wherein:

said step of implanting the trench bottom dopant regions further comprising a step of applying a tilt angle implant through the trenches to form at lease an intermediate dopant region of said second conductivity type surrounding the sidewalls of said trenches between the top sidewalls and the bottom sidewalls of the trenches.

3. The method of claim 1 wherein:

said step of implanting the trench bottom dopant regions further comprising a step of implanting dopant ions of the second conductivity type at substantially at a zero degree into said trenches.

4. The method of claim 3 wherein:

said step of lining a Schottky barrier metal layer on sidewalls of said trenches further comprising a step of filling said trenches with the Schottky barrier metal.

5. The method of claim 1 wherein:

said step of applying the first mask on the semiconductor substrate of the first conductivity is a step of applying the first mask on the semiconductor substrate of a N-type semiconductor substrate.

6. The method of claim 4 wherein:

said step of filling said trenches with the Schottky barrier metal comprising a step of filling said trenches with a Ti/TiN metal.

7. The method of claim 4 wherein:

said step of filling said trenches with the Schottky barrier metal comprising a step of filling said trenches with a Tungsten metal.

8. The method of the claim 1 wherein:

said step of opening said trenches further comprising a step of opening said trenches with non-rounded trench bottom corners.

9. A Schottky diode comprising:

at least a trenched opened in a semiconductor substrate of a first conductivity type wherein said trench filled with a Schottky barrier metal; and

a plurality of dopant region of a second conductivity type opposite to the first conductivity type surrounding sidewalls of said trench distributed along a depth of said trench for shielding a reverse leakage current through said sidewall of said trench, said plurality of dopant regions of the second conductivity type further comprising a top doped region overlapping said Schottky barrier metal near a top portion of the trench and a bottom doped region 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 filled with said Schottky barrier metal wherein 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.