Patent ID: 6252288
Filing Date: 2001-06-26
Classification: H01L,H02M

Abstract:
A rectifier device, comprising:an N.sup.+ layer,a first layer of metal on said N.sup.+ layer providing a first connection point for said device,an N.sup.- drift layer on said N.sup.+ layer opposite said first layer of metal,a first pair of trenches recessed vertically into said drift layer opposite said N.sup.+ layer, said trenches separated by a mesa region,a layer of oxide lining the sides of each of said trenches to form oxide side-walls in each of said trenches,a respective shallow P.sup.+ region in said N.sup.- drift layer at the bottom of each of said trenches which extends around the corners at the bottoms of said sidewalls to protect said corners from high peak electric fields when said device is reverse-biased, the separation between said shallow P.sup.+ regions being less than the ambipolar diffusion length of the device,a conductive material in each of said trenches for conducting current from the top of each trench to its respective shallow P.sup.+ region, said conductive material comprising polysilicon which has been heavily-doped with acceptors, 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 a second connection point for said device,said N.sup.+ layer, said N.sup.- drift layer, said first and second layers of metal, said first pair of trenches, said layer of oxide, said respective shallow P.sup.+ regions, and said conductive material arranged such that a voltage applied across said connection points which forward-biases the device produces conductivity modulation in said drift region allowing current to flow from said second to said first connection point via said Schottky contact and said shallow P.sup.+ regions, and a voltage applied across said connection points which reverse-biases the device produces depletion regions alongside said side-walls and around said shallow P.sup.+ regions which provide a potential barrier that shields said Schottky contact from a high electrical field and thereby reduces reverse leakage current.