Atomic layer deposition of zirconium dioxide from zirconium tetrachloride and ozone

• ZrO2 thin films were grown by atomic layer deposition from ZrCl4 and O3.
• Relatively high substrate temperatures promoted growth of metastable ZrO2 phases.
• ZrO2 films exhibited electric properties characteristic of dielectric metal oxides.
• ZrO2 grown in hydrogen- and carbon free process contained low amounts of impurities.

ZrO2 films were grown by atomic layer deposition using ZrCl4 and O3 as precursors. The films were grown on silicon substrates in the temperature range of 220–500 °C. The ALD rate was monotonously decreasing from 0.085 to 0.060 nm/cycle in this temperature range towards the highest temperatures studied. The content of chlorine in the films did not exceed 0.2 at.% as measured by elastic recoil detection analysis. The content of hydrogen was 0.30 and 0.14 at.% in the films grown at 300 and 400 °C, respectively. Structural studies revealed the films consisting of mixtures of stable monoclinic and metastable tetragonal/cubic polymorphs of ZrO2, and dominantly metastable phases of ZrO2 below and above 300 °C, respectively. Permittivity of dielectric layers in Al/Ti/ZrO2/(TiN/)Si capacitors with 15–40 nm thick ZrO2 ranged between 12 and 25 at 100 kHz and the dielectric breakdown fields were in the range of 1.5–3.0 MV/cm.