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

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.

1 . A transient voltage suppressing (TVS) array disposed on a semiconductor substrate supporting an epitaxial layer of a first conductivity type wherein said TVS array further comprising:
 a plurality of isolation trenches opened in said epitaxial layer with a body region of a second conductivity type in said epitaxial layer between two of said trenches; and   a Zener doped region in said body region of said first conductivity type for constituting a Zener diode comprising vertically stacked PN junctions for carrying a transient current for suppressing a transient voltage.   
     
     
         2 . The TVS array of  claim 1  wherein:
 said Zener diode is further isolated by two of isolation trenches disposed immediately next to said Zener diode for isolating said Zener diode from another PN junction of said TVS array whereby a latch-up is prevented. 
 
     
     
         3 . The TVS array of  claim 1  wherein:
 said body region further comprising a low-side diode doped region of said first conductivity type for constituting a low side diode; and 
 said epitaxial layer further comprising a doped region of said second conductivity type forming a PN junction with said epitaxial layer for constituting a high-side diode for electrically connecting to said low-side diode through an input-output (I/O) contact pad. 
 
     
     
         4 . The TVS array of  claim 1  wherein:
 said epitaxial layer further comprising vertical PN junctions constituting diodes therein and electrically connecting to electrodes of a first and a second electrical conductivity types for connecting respectively to a high and low voltages disposed separately on a top surface and a bottom surface of said semiconductor substrate. 
 
     
     
         5 . The TVS array of  claim 1  wherein:
 said semiconductor substrate further comprising a N-type substrate supporting a N-type epitaxial layer to form a plurality of PN junctions in said N-type epitaxial layer as vertical PN junctions in said semiconductor substrate with an anode electrode disposed on a bottom surface of said substrate for connecting to a high voltage and a cathode electrode disposed on a top surface of said substrate for connecting to a low voltage. 
 
     
     
         6 . The TVS array of  claim 5  wherein:
 said body region is a P-body region disposed between two of said isolation trenches in said N-type epitaxial layer wherein said body region further encompassing a Zener N-doped region to form a vertically stacked PN junctions constituting a Zener diode between two of said isolation trenches. 
 
     
     
         7 . The TVS array of  claim 5  wherein:
 said body region is a P-body region disposed between two of said isolation trenches in said N-type epitaxial layer wherein said body region further encompassing a N-doped region to form a PN junction with said P-body to function as a low side diode of said TVS array 
 
     
     
         8 . A method for manufacturing a transient voltage suppressing (TVS) array substantially following a manufacturing process for manufacturing a vertical semiconductor power device, the method comprising:
 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 said isolation trenches; and   applying an source mask for implanting a plurality of doped regions of said first conductivity type constituting a plurality of diodes wherein said isolation trenches isolating and preventing parasitic PNP or NPN transistor due to a latch-up between said doped regions of different conductivity types.   
     
     
         9 . The method of  claim 8  further comprising:
 applying a contact mask for implanting doped regions of said second conductivity type away from said body region for constituting high side diodes with said epitaxial layer to connect to said low side diodes encompassed in said body region with input-output (IO) contact pads across said isolation trenches. 
 
     
     
         10 . The method of  claim 8  wherein:
 said step implanting a plurality of doped regions of said first conductivity type constituting a plurality of diodes in said step further comprising a step of forming a Zener doped region with a greater width wherein said Zener doped region comprising vertically stacked PN junctions for functioning as a Zener diode with said body region in said epitaxial layer. 
 
     
     
         11 . The method of  claim 10  wherein:
 said step opening a plurality of isolation trenches further comprising a step of opening isolation trenches immediately next to said Zener diode for isolating said Zener diode for preventing said latch-up between said doped regions of different conductivity types. 
 
     
     
         12 . The method of  claim 8  further comprising:
 depositing a metal layer on a bottom surface of said substrate to function as an electrode for said TVS array. 
 
     
     
         13 . The method of  claim 8  further comprising:
 depositing a metal layer on a to surface of said substrate and patterning said metal layer to function as input-output contact pads and as an electrode for said TVS array of an opposite conductivity from an electrode formed on said bottom surface of said semiconductor substrate.