Characterisation of HfO2 deposited by photo-induced chemical vapour deposition

The deposition of thin Hafnia (HfO2) films on crystalline Si by photo-induced CVD using 222 nm excimer lamps at temperatures between 300 and 450 C is presented. Hafnium (IV) tetra-t-butoxide was used as the precursor, which was carried into the photochemical reaction chamber by flowing Ar carrier gas at a pressure of several mbar using a special precursor injection system. Films from approximately 6-70 nm in thickness with refractive indices from 1.60 to 1.85 were grown. The deposition rate measured by ellipsometry was found to be 15 nmmin-1 at a temperature of 400 C. The deposited HfO2 films were characterised by various techniques. XRD showed that as-deposited HfO2 films were basically amorphous. Fourier transform infrared spectroscopy, revealed that Hf-O absorption in the photo-CVD deposited HfO2 films is quite different at various deposition parameters. The substrate temperature, system pressure and UV-annealing dependence of the physical and interfacial properties of these films will also be presented. 31 refs.