Advantage of La2O3 gate dielectric over HfO2 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.