The electrical characteristics, i.e. leakage current and capacitance, of ZrO2 based metal–insulator–metal structures, grown at 225, 250 and 275 °C by atomic layer deposition, were studied. The lowest leakage current was obtained at 250 °C deposition temperature, while the highest dielectric constant (k ∼ 43) was measured for the samples grown at 275 °C, most probably due to the formation of tetragonal/cubic phases in the ZrO2 layer. We have shown that the main leakage current of these ZrO2 capacitors is governed by the Poole–Frenkel conduction mechanism. It was observed by x-ray photoelectron spectroscopy depth profiling that at 275 °C deposition temperature the oxygen content at and beyond the ZrO2/TiN interface is higher than at lower deposition temperatures, most probably due to oxygen inter-diffusion towards the electrode layer, forming a mixed TiN–TiOxNy interface layer. At and above 275 °C the ZrO2 layer changes its structure and becomes crystalline as proven by XRD analysis.

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The influence of the annealing atmosphere and temperature on the crystalline phase and composition of thin ZrO2 layers grown by atomic layer deposition on silicon is analyzed. These physical parameters are correlated with the electrical performance of ZrO2 in metal-insulator-semiconductor capacitor structures. For this study, 5.3 nm thick ZrO2 films were annealed at selected temperatures in the range of 400-900 degrees C in either nitrogen or ammonia atmospheres. As shown by grazing-incidence x-ray diffraction, the films start to crystallize at temperatures above 400 degrees C, resulting in a capacitance increase. An annealing in NH3 results in a higher capacitance increase than annealing in N-2. Angular-resolved x-ray photoelectron spectroscopy and secondary ion mass spectrometry show no changes in the chemical composition of ZrO2 after annealing in N-2. In contrast, a significant amount of nitrogen is incorporated into the ZrO2 film and at the ZrO2/Si interface during the temperature treatment in NH3, as also indicated by energy-filtered transmission electron microscopy

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