Deposition temperature effect on electrical properties and interface of high-k ZrO2 capacitor

The electrical characteristics, i.e. leakage current and capacitance, of ZrO2 based metal-insulator-metal structures, grown at 225, 250 and 275 degrees C by atomic layer deposition, were studied. The lowest leakage current was obtained at 250 degrees C deposition temperature, while the highest dielectric constant (k similar to 43) was measured for the samples grown at 275 degrees 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 degrees 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 degrees C the ZrO2 layer changes its structure and becomes crystalline as proven by XRD analysis.