Tantalum-gate thin-film SOI nMOS and pMOS for low-power applications

The threshold voltages of thin-film fully-depleted silicon-on-insulator (FDSOI) nMOS and pMOS have been controlled by employing tantalum (Ta) as the gate materials. Ta-gate FDSOI MOSFET's have excellent threshold voltage control for 1.0 V application on low impurity concentration SOI layers in both nMOS and pMOS. The low-temperature processing after the gate oxidation step leads to good on/off characteristics in Ta-gate SOI MOSFET's because of no reaction between Ta gate electrode and SiO2 gate insulator. This technology makes it possible to drastically decrease the number of the process steps for CMOS fabrication, because the same gate material is available for both nMOS and pMOS.