Effects of buried oxide stress on thin-film silicon-on-insulator metal–oxide–semiconductor field-effect transistor

Thin-film silicon-on-insulator (SOI) device characteristics have been investigated in terms of stress in the buried oxide interface by both simulation and experiment. Bonded SOI wafer with a 400 nm buried oxide and SOI wafer with a 100 nm buried oxide which is made by implanted oxygen are used as a substrate for device fabrication. From the simulation, it is demonstrated that the 100 nm buried oxide has higher compressive stress than the 400 nm counterpart after the local oxidation of silicon process. With the highly compressive-stressed buried oxide, boron atoms may accumulate at the silicon side, especially at the silicon edge, under tensile stress so that these accumulated boron atoms increase threshold voltage of the edge channel. Therefore, it is found that there is no hump of the drain current in the subthreshold drain current–gate-voltage characteristics of thin-film SOI n-channel metal–oxide–semiconductor field-effect transistors (MOSFET) with the highly compressed buried oxide.