Patent ID: 9748383
Date: 2017-08-29
CPC Classifications: H01L

Claim:
1. A Metal Oxide Semiconductor (MOS) power transistor comprising: a source; a gate; and a drain, the source, gate and drain being located in or on a well structure of a first doping polarity located in or on a substrate; wherein each of the source and the drain is provided with a first structure comprising: a first region forming a first drift region, the first region being of a second doping polarity opposite the first doping polarity; a second region of the second doping polarity in the first region, the second region being a well region and having a doping concentration which is higher than the doping concentration of the first region; a third region of the second doping polarity in or on the second region, wherein the third region does not contact the first region and wherein the doping concentration of the first region is such that the first region is substantially fully depleted, and breakdown occurs at a junction between the first region and the well structure, the junction being substantially parallel to the surface of the device; and a pair of isolators disposed at least partially in the first drift region, wherein the third region is surrounded by the second region and the pair of isolators so that during operation of the transistor current flowing between the source and the drain must pass through the second region.