Trenched schottky rectifiers

Abstract

Inner trenches ( ) of a trenched Schottky rectifier ( ) bound a plurality of rectifier areas ( ) where the Schottky electrode ( ) forms a Schottky barrier with a drift region ( ). A perimeter trench ( ) extends around the outer perimeter of the plurality of rectifier areas ( ). These trenches ( ) accommodate respective inner field-electrodes ( ) and a perimeter field-electrode ( ) that are connected to the Schottky electrode ( ). The inner field-electrodes ( ) are capacitively coupled to the drift region ( ) via dielectric material ( ) that lines the inner trenches ( ). The perimeter field-electrode ( ) is capacitively coupled across dielectric material ( ) on the inside wall ( ) of the perimeter trench , without acting on any outside wall ( ). Furthermore, the inner and perimeter trenches ( ) are closely spaced and the intermediate areas ( ) of the drift region ( ) are lowly doped. The spacing is so close and the doping is so low that the depletion layer ( ) formed in the drift region ( ), from the Schottky barrier ( ) and from the field-relief regions ( ) in the blocking state of the rectifier, may deplete the whole of the intermediate areas ( ) between the trenches ( ) at a blocking voltage just below the breakdown voltage. This arrangement reduces the risk of premature breakdown that can occur at high field points in the depletion layer ( ), especially at the perimeter of the array of rectifier areas ( ).