Electrical Characterizations of HfO2/Al2O3/Si as Alternative Gate Dielectrics

HfO$_2$/Al$_2$O$_3$ film was studied to improve the thermal stability of HfO$_2$ film. Oxidized HfO$_2$ and HfO$_2$/Al$_2$O$_3$ films were made up with similar thickness. Insertion of amorphous Al$_2$O$_3$ film to form HfO$_2$/Al$_2$O$_3$ film effectively suppressed growth of an interfacial layer during oxidation in a furnace at 550 $^\circ$C for 2 hours. Capacitance of as-deposited HfO$_2$/Al$_2$O$_3$ film was higher than that of HfO$_2$ film. Although an interlayer of Al$_2$O$_3$ film had comparatively lower dielectric constant, both films had similar capacitance values at 650 $^\circ$C annealing temperature. The hysteresis phenomenon was suppressed after high-temperature annealing when an Al$_2$O$_3$ layer was inserted between HfO$_2$ and Si substrate. Moreover, the breakdown voltage of HfO$_2$/Al$_2$O$_3$ film was larger than that of HfO$_2$ film. KCI Citation Count: 10