Junction barrier Schottky (JBS) with floating islands

• US 8,227,330 B2
• Filed: 02/11/2010
• Issued: 07/24/2012
• Est. Priority Date: 02/11/2005
• Status: Active Grant

• Current Assignee: Alpha & Omega Semiconductor, Ltd.
• Original Assignee: Alpha & Omega Semiconductor, Ltd.
• Inventors: Pan, Ji, Bhalla, Anup
• Primary Examiner(s): Mandala, Victor A
• Assistant Examiner(s): AHMED, SELIM U
• Application Number:
  US12/658,434
• Publication Number:
  US 20100155876A1
• Time in Patent Office: 894 Days
• Field of Search: 438/169, 438/534, 438/192, 438570-582, 257/284, 257/471, 257/478, 257/483, 257/484, 257/928, 257/E27.4, 257/E21.359, 257/E29.338, 257/E21.368, 257/E29.013
• US Class Current: 438/576
• 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 method for manufacturing a Schottky diode comprising:

opening a plurality of trenches in an N-type semiconductor substrate and implanting a plurality of P-type dopant regions under said trenches as floating islands in said semiconductor substrate as vertically implanted regions through said trenches wherein each of said floating islands having a width substantially same or slightly broader than a width of said trenches; and

filling the trenches with a Schottky barrier metal.

5. The method of claim 1 wherein:

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

2. A method for manufacturing a Schottky diode comprising:

opening a plurality of trenches in a P-type semiconductor substrate and implanting a plurality of N-type dopant regions under said trenches as floating islands in said semiconductor substrate as vertically implanted regions through said trenches wherein each of said floating islands having a width substantially same or slightly broader than a width of said trenches; and

filling the trenches with a Schottky barrier metal.

3. The method of claim 2 wherein:

said step of filling said Schottky barrier metal in said trenches further comprising a step of filling a Ti/TiN or a tungsten metal into said trenches for forming a Schottky barrier in said trenches above said vertically aligned buried dopant regions.

4. The method of claim 2 further comprising:

disposing a dielectric layer on sidewalls of said trenches and filling the trenches with a Schottky barrier metal to form a Schottky barrier in said trenches.

6. The method of claim 2 wherein:

said step of filling said Schottky barrier metal in said trenches further comprising a step of disposing a Schottky barrier metal on sidewalls of said trenches to form a Schottky barrier along sidewalls of said trenches.