Abstract
The electrical and dielectric properties of HfAlOx films deposited by radio frequency magnetron cosputtering of HfO2 and Al2O3 targets with Au as the bottom electrode and Pt, Au, and Al as the top electrodes forming metal-insulator-metal (MIM) structures have been studied. HfAlOx layers are characterized by X-ray photoelectron spectroscopy to examine the chemical composition. Atomic force microscopy morphology study shows that root mean square value of surface roughness of the film decreases after annealing. From grazing incidence X-ray diffraction study, it is observed that the deposited films remain amorphous up to 600 C annealing temperature. For electrical characterization, current-voltage and capacitance-voltage characteristics were studied in the frequency range of 1 kHz-1 MHz. MIM capacitors with Pt (Phi(pt) similar to 5.6 eV) top electrode were found to have the lowest leakage current of similar to 6 x 10(-6) A cm(-2) (at -1 V) and low energy dissipation with improved voltage coefficients of capacitance values (81 ppm/V-2). Low field (<1 MV/cm) conduction mechanism was found to be dominated by Schottky emission, while at high field (>1 MV/cm) it is dominated by Poole-Frenkel mechanism. Change in the quadratic voltage coefficient of capacitance under different stress voltages was found to be the lowest with Pt top electrode. (c) 2010 The Electrochemical Society. [DOI: 10.1149/1.3514656] All rights reserved.