Comparison of hole mobility in LOCOS-isolated thin-film SOI p-channel MOSFET´s fabricated on various SOI substrates

The hole mobility of LOCOS-isolated thin-film silicon-on-insulator (SOI) p-channel MOSFET´s fabricated on SOI substrates with different buried oxide thickness has been investigated. Two types of SOI wafers are used as a substrate: (1) SIMOX wafer with 100-nm buried oxide and (2) bonded SOI wafer with 100-nm buried oxide. Thin-film SOI p-MOSFET´s fabricated on SIMOX wafer have hole mobility that is about 10% higher than that on bonded SOI wafer. This is caused by the difference in the stress under which the silicon film is after gate oxidation process. This increased hole mobility leads to the improved propagation delay time by about 10%.