Synthesis of ZrO2 thin films by atomic layer deposition: growth kinetics, structural and electrical properties

Ultra thin films of ZrO2 were synthesized on soda lime glass and SnO2-coated glass, using ZrCl4 and H2O precursors by atomic layer deposition (ALD), a sequential CVD technique allowing the formation of dense and homogeneous films. The effect of temperature on the film growth kinetics shows a first temperature window for ALD processing between 280 and 350 °C and a second regime or “pseudo-window” between 380 and 400 °C, with a growth speed of about one monolayer per cycle. The structure and morphology of films of less than 1 μm were characterized by XRD and SEM. From 275 °C, the ZrO2 film is crystallized in a tetragonal form while a mixture of tetragonal and monoclinic phases appears at 375 °C. Impedance spectroscopy measurements confirmed the electrical properties of ZrO2 and the very low porosity of the deposited layer.