Characteristics of ZrO2 films with Al and Pt gate electrodes

We investigated interfacial stabilities of ZrO2 films with Al and Pt electrodes formed by magnetron sputtering upon annealing and consequent changes of their metal-oxide-semiconductor capacitor characteristics. The as-deposited ZrO2 films deposited using a sputtering power of 300 W were amorphous, while after annealing in N-2 at 600degreesC for 5 min the films became polycrystalline with a mixture of monoclinic and tetragonal phases. After the deposition of electrodes, we found that the amorphous interlayer which is presumed to be Al2O3 was formed at the ZrO2/Al interface, while platinum (Pt) electrodes showed no interlayer at the interface with ZrO2 films. The value of the capacitance equivalent thickness for the ZrO2 film with the Al electrode was larger than that of the case with the Pt electrode by about 12 Angstrom, which is due to the presence of the additional Al2O3 interlayer at the Al/ZrO2 interface. The capacitance-voltage measurement showed that the difference in flatband voltage (V-FB) between the ZrO2 films and the two different electrodes is about 1.2 V, which is due to the work function difference between the two electrode materials. (C) 2003 The Electrochemical Society.