Method of manufacturing a semiconductor device

摘要

A semiconductor device having the high integration and great driving ability is provided. An upper gate oxide film is formed on a gate electrode. An upper drain region is formed on a lower drain region through an oxide film, and an upper source region is formed on a lower source region through the oxide film. A polysilicon region is formed on the upper gate oxide film provided between the upper drain region and the upper source region. The lower layer portion of the polysilicon region is defined as a channel region.