Patent ID: 6252258
Filing Date: 2001-06-26
Classification: H01L

Abstract:
A rectifier device, comprising:an N+ layer;a first layer of metal on said N+ layer providing a cathode connection point for said rectifier device;an N- drift layer on said N+ layer opposite said cathode;a pair of trenches recessed into said drift layer opposite said N+ layer, said trenches separated by a mesa region comprised of that portion of said N- drift layer found between said pair of trenches;a layer of oxide lining the sides and bottom of each of said trenches to form oxide side-walls and respective oxide bottoms in each trench;respective shallow P regions extending from the oxide bottoms of respective trenches into said N- drift layer, each of said shallow P regions extending around the corners formed at the intersections of its respective trench's oxide side-walls and oxide bottom;a conductive material in each of said trenches; anda second layer of metal contacting said mesa region, said conductive material, and said oxide side-walls, said second layer of metal forming a Schottky contact at its interface with said mesa region, said second layer of metal providing an anode connection point for said rectifier device;said device structure arranged such that a voltage applied across said anode and cathode which is greater than the barrier height of said Schottky contact allows current to flow from said anode to said cathode via said Schottky contact, and a voltage applied across said anode and cathode which reverse-biases the device produces depletion regions alongside said side-walls and around said shallow P regions which provide a potential barrier across said mesa region that shields said Schottky contact from a high electrical field and thereby reduces reverse leakage current, each of said shallow P regions protecting said trench corners from premature breakdown due to high electric fields and thereby improving the reliability of the trench oxide.