Electrical characterizations of HfO2/Al2O3/Si as alternative gate dielectrics

Abstract

HfO2/Al2O3 film was studied to improve the thermal stability of HfO2 film. Oxidized HfO2 and HfO2/Al2O3 films were made up with similar thickness. Insertion of amorphous Al2O3 film to form HfO2/Al2O3 film effectively suppressed growth of an interfacial layer during oxidation in a furnace at 550 degrees C for 2 hours. Capacitance of as-deposited HfO2/Al2O3 film was higher than that of HfO2 film. Although an interlayer of Al2O3 film had comparatively lower dielectric constant, both films had similar capacitance values at 650 degrees C annealing temperature. The hysteresis phenomenon was suppressed after high-temperature annealing when an Al2O3 layer was inserted between HfO2 and Si substrate. Moreover, the breakdown voltage of HfO2/Al2O3 film was larger than that of HfO2 film.