Patent ID: 6201280
Filing Date: 2001-03-13
Classification: H01L

Abstract:
A transistor of SiC for high voltage and high switching frequency applications having an insulated gate and being one of:a MISFET; andan IGBT;said transistor comprising, superimposed on each other in the following order:a drain;a highly doped substrate layer being of n-type when said transistor is a MISFET and being of p-type when said transistor is an IGBT;a highly doped n-type buffer layer when said transistor is an IGBT; and a low doped n-type drift layer;said transistor further comprising a plurality of laterally spaced unit cells, each having:a highly doped n-type source region layer;a source arranged on top of the source region layer;a p-type channel region layer separating the source region layer from the drift layer;an insulating layer located adjacent to the channel region layer and extending from the source region layer to the drift layer and to the channel region layer and source region layer of an adjacent unit cell; anda gate electrode arranged on the insulating layer and adapted to form a conducting inversion layer extending in the channel region layer at the interface to the insulating layer for electron transport from the source to the drain upon applying a voltage thereto, the center-to-center distance between two adjacent unit cells defining a lateral width of a unit cell of the transistor;wherein:the relation of the lateral width of an accumulation region, defined as the region in the drift layer connecting to the insulating layer in each individual cell, and the lateral cell width is selected so as to minimize the total power losses in the transistor and to control the proportion of the power losses in the transistor as a consequence of switching, relative to the power losses relating to conduction of the transistor, for a predetermined switching frequency and on-state voltage for which the transistor is designed; andsaid lateral cell width is more than ten times larger than the lateral width of said accumulation region.