Latch-up free vertical TVS diode array structure using trench isolation

• US 7,880,223 B2
• Filed: 11/30/2006
• Issued: 02/01/2011
• Est. Priority Date: 02/11/2005
• Status: Active Grant

• Current Assignee: Alpha & Omega Semiconductor, Ltd.
• Original Assignee: Alpha & Omega Semiconductor, Ltd.
• Inventors: Bobde, Madhur
• Primary Examiner(s): Le; Thao X
• Assistant Examiner(s): HUBER, ROBERT T
• Application Number:
  US11/606,602
• Publication Number:
  US 20070073807A1
• Time in Patent Office: 1,524 Days
• Field of Search: 257/328, 257/355, 257/362, 257/372, 257/374, 257/E27.033
• US Class Current: 257/328
• 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 method for manufacturing a transient voltage suppressing (TVS) array substantially following a manufacturing process for manufacturing a vertical semiconductor power device. The method includes a step of opening a plurality of isolation trenches in an epitaxial layer of a first conductivity type in a semiconductor substrate followed by applying a body mask for doping a body region having a second conductivity type between two of the isolation trenches. The method further includes a step of applying an source mask for implanting a plurality of doped regions of the first conductivity type constituting a plurality of diodes wherein the isolation trenches isolating and preventing parasitic PNP or NPN transistor due to a latch-up between the doped regions of different conductivity types.

Claims

1. A transient voltage suppressing TVS array comprising:

a first high-side and a first-low side steering diodes of said TVS array formed as dopant regions of different conductivity types for constituting PN junctions in a semiconductor substrate;

an isolation trench disposed between said first high-side and said first-low side steering diodes disposed immediately on both sides of said isolation trench wherein said first high-side and said first low-side steering diodes are electrically connected in series to a common Input/output (I/O) terminal as a first I/O terminal pad; and

wherein said isolation trench covered by an insulation layer underneath said first I/O terminal pad and filled with an insulation material therein for isolating and preventing a latch-up of parasitic PNP or NPN transistor between said doped regions in said semiconductor substrate of different conductivity types for suppressing a snap back of a voltage on said common I/O terminal for suppressing a transient voltage;

a main Zener diode comprising a body region of a second conductivity type disposed in an epitaxial layer of a first conductivity and said Zener diode is disposed between said first and second low-side steering diodes isolated from said first and second high-side steering diodes by two of said isolation trenches wherein said Zener diode is electrically connected to a cathode terminal as a separate electrical terminal from said first and second I/O terminal pads;

at least two additional PN junctions disposed immediately adjacent to and isolated by a second isolation trench connected in series to a second input/output (I/O) terminal pad functioning respectively as a second high-side steering diode and a second low-side steering diode wherein said second isolation trench is covered with an insulation layer underneath said second I/O terminal pad and filled with an insulation material therein;

said semiconductor substrate further comprising a N-type substrate supporting said epitaxial layer of a N-type conductivity wherein said semiconductor substrate with an anode electrode disposed on a bottom surface of said substrate for connecting to a high voltage and said cathode electrode disposed on a top surface for connecting said Zener diode to a low voltage; and

a dopant region of a N-conductivity type in said P-body region for constituting a NPN transistor with said body region and said epitaxial layer wherein said dopant region of said N-conductivity type is disposed near a top surface of said semiconductor substrate for directly connecting to said cathode electrode and is triggered on by said main Zener diode to conduct a large transient current with a low resistance.

2. The TVS array of claim 1 wherein:

said first and second low-side steering diodes further comprising a first and second N-dopant regions formed in said body region on two opposite side of said Zener diode and said first and second high-side steering diodes further comprising a first and second P-dopant regions disposed in said N-type epitaxial layer wherein said first high side steering diode and said first low side steering diode are insulated by said first insulation trench and said second high side steering diode and said second low side steering diode are insulated by said second insulation trench in said semiconductor substrate and interconnected in series by said first and second I/O terminal pads respectively.