Trench moseft with trench gates underneath contact areas of esd diode for prevention of gate and source shortate

Abstract

A trench DMOS transistor having overvoltage protection and prevention for shortage between gate and source when contact trenches are applied includes a substrate of a first conductivity type and a body region of a second conductivity type formed over the substrate. Trench gates extend through the body region and the substrate. An insulating oxide layer lines the trench and overlies the body region. A conductive electrode is deposited in the trench so that it overlies the insulating layer. A source region of the first conductivity type is formed in the body region adjacent to the trench. An undoped polysilicon layer overlies a portion of the insulating layer defining the Zener diode region. A plurality of cathode regions of the first conductivity type is formed in undoped polysilicon layer. At least one anode region is in contact with adjacent ones of the plurality of cathode regions. Trench gates underneath the Zener diode act as the buffer layer for prevention of shortage between gate and source.

Dependencies are inferred from the claim text.