Atomic layer deposition of hafnium silicate films using hafnium tetrachloride and tetra-n-butyl orthosilicate

Atomic layer chemical vapor deposition (ALCVD) of hafnium silicate films with a precursor combination of HfCl 4 and TBOS (tetra-n-butyl orthosilicate) was studied for high dielectric gate insulators. The effect of deposition conditions, such as deposition temperature and pulse time for precursor injection on the deposition rate per cycle and composition of the film (fraction of hafnia phase in the silicate film) were studied. The growth rate and composition ratio were saturated with the increase of the injection time of HfCl 4 and TBOS and decreased with the increased deposition temperature from 300 to 500 °C. The growth rate was 1.4 Å/cycle and the fraction of hafnium phase in the Hf silicate thin films was 0.19 at the deposition temperature of 500 °C. Impurity content, such as carbon and chlorine was below the detection limit of XPS (x-ray photoelectron spectroscopy) and the impurity level detected by SIMS decreased with increasing deposition temperature. It was found that the incorporation rate of metal from halide source was lower than alkoxide source.