Electrode effects on the conduction mechanisms in HfO2-based metal-insulator-metal capacitors

The impact of top-electrode metal on the conduction mechanisms of HfO2 thin films-based metal-insulator-metal capacitors was investigated at temperature ranging from 25 to 150 degrees C. Al, Cr, and Au are considered as top electrodes whereas Pt constitutes the commune bottom electrode. It was found for both capacitors that in the high field region, the leakage mechanism is electrode-limited. The leakage current, measured at the Al/HfO2 and Cr/HfO2 interfaces, was largely governed by Fowler-Nordheim tunneling in the whole measured temperature range. The barrier heights, at the Al/HfO2 and the Cr/HfO2 interfaces, were around 0.77 and 0.95 eV, respectively. In the case of Au/HfO2/Pt capacitors, the Au/HfO2 interface acts as a Schottky barrier with a height of 1.06 eV. (C) 2009 American Institute of Physics. [doi:10.1063/1.3226857]