A MOS type field effect transistor includes a columnar insulation layer (22) formed in a concave portion of semiconductor layer (23) that is formed on a main surface of a semiconductor substrate (21). One source drain region (15) is formed annularly in the main surface of the substrate (21) and outwardly...http://www.google.de/patents/US5312767?utm_source=gb-gplus-sharePatent US5312767 - MOS type field effect transistor and manufacturing method thereof
