A novel thermally-stable zirconium amidinate ALD precursor for ZrO2 thin films

ZrO2 thin films were deposited by the atomic layer deposition process on Si substrates using tetrakis(N,N′-dimethylacetamidinate) zirconium (Zr-AMD) as a Zr precursor and H2O as an oxidizing agent. Tetrakis (ethylmethylamino) zirconium (TEMA-Zr) was also evaluated for a comparative study. Physical properties of ALD-derived ZrO2 thin films were studied using ellipsometry, grazing incidence XRD (GI-XRD), high resolution TEM (HRTEM), and atomic force microscopy (AFM). The ZrO2 deposited using Zr-AMD showed a better thermal stability at high substrate temperature (>300 °C) compared to that using TEMA-Zr. GI-XRD analysis reveals that after 700 °C anneal both ZrO2 films enter tetragonal phase. The electrical properties of N2-annealed ZrO2 film using Zr-AMD exhibit an EOT of 1.2 nm with leakage current density as low as 2 × 10−3 A/cm2 (@Vfb−1 V). The new Zr amidinate is a promising ALD precursor for high-k dielectric applications.