Effects of buried oxide on electrical performance of thin-film silicon-on-insulator metal-oxide-semiconductor field-effect transistor

Local oxidation of silicon-isolated 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. A bonded SOI wafer with a 400 nm buried oxide and a separation by implanted oxygen SOI wafer with a 100 nm buried oxide are used for device fabrication. In the 100 nm buried-oxide case, boron atoms are accumulated at the silicon side in the interface between the silicon film and oxide (i.e., including the buried oxide and field oxide) due to a highly stressed oxide so that the increased boron concentration increases the threshold voltage of the edge channel. Therefore, it is found that there is no drain current hump in the subthreshold region of thin-film SOI n-channel metal-oxide-semiconductor field-effect transistors with 100 nm buried oxide. 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. (C) 1999 American Institute of Physics. [S0021-8979(99)01407-3].