Semiconductor device and method of manufacturing the same

摘要

A semiconductor substrate of a first conduction type is provided for serving as a common drain to a plurality of power MISFET cells. A middle semiconductor layer is formed on the semiconductor substrate and has a lower impurity concentration than that of the semiconductor substrate. Pillar regions are formed on the middle semiconductor layer and include semiconductor regions of the first conduction type having a lower impurity concentration than that of the middle semiconductor layer.