Advantage of La 2 O 3 gate dielectric over HfO 2 for direct contact and mobility improvment

Advantage of La 2 O 3 over HfO 2 MOSFET has been experimentally examined. Silicate reaction especially observed at La 2 O 3 /Si interface has been found to suppress the formation of SiO 2 layer to realize direct contact, which is useful for further scaling in equivalent oxide thickness (EOT). Due to the lack of interfacial layer, La 2 O 3 has showed relatively high interfacial state density, however, the effective mobility has exceeded to that of HfO 2 MOSFET. Mobility analysis has revealed an additional Coulomb scattering at small EOT, suggesting the influence of metal gate. A simple mobility degradation model is pointed out using metal induced defects.