Growth of chemical vapor deposition aluminum titanate films at different CO2/H2 and aluminum butoxide inputs

Abstract

Amorphous aluminum titanate films are prepared on silicon substrates by low-pressure chemical vapor deposition (CVD) using a mixture of aluminum tri-sec-butoxide (ATSB), titanium tetrachloride (TiCl4), CO2, and H2 as the reactants (the ATSB/TiCl4/CO2/H2 system). The effects of the CO2/H2 and ATSB inputs and substrate temperature on the growth, microstructure, and composition of the CVD Al2O3–TiO2 films are discussed. The films have an increased growth rate and an increased Ti content at lower temperatures. The adsorption-controlled reaction is identified, which is attributed to the gas/solid reaction to weaken the film/substrate interface. The growth rates are also higher at higher H2 and ATSB flows. The film thickness is 0.47–1.13 μm for the CO2/H2-varying system and of 0.34–1.37 μm for the ATSB-varying system at deposition temperatures of 350–500 °C. The proposed reactions are presented to explain the film growth. The determined adsorption energy can explain the effect of temperature on composition.