SEMICONDUCTOR DEVICE AND MANUFACTURE THEREOF

摘要

PURPOSE: To provide an FET structure in which roll-off of threshold voltage of a short channel is improved, and leakage currents of a source channel and a drain channel are reduced. CONSTITUTION: An FET 34 composed of a source area 36, a channel area 40, and a drain area 38 is manufactured on a semiconductor material substrate 24 provided on an upper side of an insulating layer formed further on an upper surface of a semiconductor material base substrate 10. A gate area 42 is provided further on the FET 34 which is located on the channel 40 and is separated from the same. The base substrate 10 includes a mesa area 18 extending to an insulating layer located below the channel 40 so that the base substrate 10 more approaches the channel 40 than areas of the source 36 and drain 38 do. Thus, the channel 40 is shielded from source and drain voltages and hence the influence is reduced from them.