Orthorhombic ZrO2 thin films via atomic layer deposition from tris(dimethylamino)cyclopentadienyl zirconium and water

Different zirconium dioxide phases exhibit attractive functional properties, making them suitable for various applications. Among these, orthorhombic o-ZrO₂ is of particular interest due to its distinctive ferroelectric behavior. However, synthesizing phase-pure o-ZrO₂ thin films has remained challenging. Here, we demonstrate a robust water-based atomic layer deposition (ALD) process for high-quality polycrystalline o-ZrO₂ thin films using tris(dimethylamino)cyclopentadienyl zirconium as the precursor. In the deposition temperature range of 200–250 °C the processes yielded essentially phase-pure o-ZrO₂ films with a growth-per-cycle (GPC) of 0.5 Å/cycle, whereas above 275 °C monoclinic m-ZrO₂ films were obtained with GPC of 0.6 Å/cycle. Interestingly, longer relaxation times during deposition were found to affect the growth rate, suggesting changes in crystallization dynamics and stabilization of different orthorhombic space groups. The films were characterized by grazing-incidence X-ray diffraction (GIXRD), X-ray reflectivity (XRR), ellipsometry, and X-ray photoelectron spectroscopy (XPS) analyses.