Determination of Flat-Band Voltages for Fully Depleted Silicon-on-Insulator (SOI) Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFET's)

Publisher Website
Google Scholar
Abstract
A method to determine the flat-band voltage, V FB, in silicon-on-insulator (SOI) metal-oxide semiconductor (MOS) structures has been proposed. It is based on the measurement of the back channel threshold voltages of SOI MOS field-effect transistors (MOSFET's) as a function of the front gate bias. This method is very useful for fully depleted SOI MOSFET's with a low channel dopant concentration. Mean values of V FB's obtained from this method were -0.79 V for n+ polysilicon gate SOI n-MOSFET's with a gate oxide of 205 Å and an acceptor concentration of 4×1015 cm-3, and -0.12 V for n+ polysilicon gate SOI p-MOSFET's with a gate oxide of 205 Å and a donor concentration of 5×1015 cm-3. The accuracy in the determination of V FB is mainly dependent on precise evaluations of the front gate oxide thickness, the surface silicon thickness, and the channel dopant concentration.