Influence of growth temperature on the structure and electrical properties of high-permittivity TiO2 films in TiCl4-H2O and TiCl4-O3 atomic-layer-deposition processes



The influence of the growth temperature on structure and the electrical properties of TiO2 thin films deposited from TiCl4 and H2O and from TiCl4 and O3 was investigated in the temperature range of 150–500 °C. The high-permittivity rutile phase of TiO2 was obtained on RuO2 in both processes at 225 °C and higher substrate temperatures. The films deposited on Si contained rutile only when were deposited from TiCl4 and H2O at temperatures above 425 °C. Comparison of the films grown on RuO2 revealed superior electrical performance of those deposited from TiCl4 and O3. Although the k values ranging from 100 to 130 in the Pt/TiO2/RuO2 structures were somewhat lower for these films than for the films deposited from TiCl4 and H2O, the former process resulted in lower leakage current densities at similar capacitance effective thicknesses (CET). The leakage current density as low as 6.6 × 10−8 A cm−2 at 0.8 V and CET = 0.41 nm was obtained for films deposited from TiCl4 and O3 at 350 °C.