Patent ID: 6720616
Filing Date: 2004-04-13
Classification: H01L

Abstract:
A trench MOS transistor, comprising:a semiconductor body with a first conductivity type forming at least one drain zone and formed of a semiconductor substrate and an epitaxial layer on said substrate, said epitaxial layer and said substrate having a junction therebetween; said semiconductor body having: a trench ending in a vicinity of said junction and having: a gate electrode; a trench side area contacting a side face of said trench; a trench upper end; and a trench lower end extending into said semiconductor body; at least one source zone with said first conductivity type, said source zone: disposed in said trench side area at said trench upper end; and having a source lower end; a first region with a second conductivity type disposed in said trench side area between said trench and an adjacent trench, said first region having a dopant gradient; and a second region with said second conductivity type, said second region: buried in said first region in said trench side area; having a higher doping and a steeper dopant gradient than said first region; disposed between said source zone and said drain zone; shaped in a strip; and having a charge carrier concentration of between 1017 to 1019 charge carriers/cm3; an insulating layer electrically isolating said gate electrode from said source zone, said first region, and said drain zone; and said insulating layer having a step forming: a first layer portion having a given thickness at said trench lower end; and a second layer portion having a thickness smaller than said given thickness at said trench upper end.