Semiconductor device and method of manufacturing the same

摘要

A semiconductor device includes a MOS-type field effect transistor (SOI-MOSFET) formed on a thin silicon layer on an insulator layer. The SOI-MOSFET has a gate overlap-type LDD structure in which additional source/drain regions having an impurity concentration of 3x1017 to 3x1018/cm3 overlapping with a gate electrode are provided in the silicon layer. According to this structure, when the SOI-MOSFET is on operation, only the additional source/drain regions are depleted, so that it is possible to obtain satisfactory transistor characteristics. Additional source/drain regions in this structure are formed by combination of vertical ion implantation using the gate electrode as a mask and thermal diffusion or oblique ion implantation using the gate electrode as a mask.