In situ Fourier transform infrared (FT-IR) spectroscopy was used to study the atomic layer deposition mechanism of hafnium silicate films with dichlorobis[bis(trimethylsilyl)amido] hafnium (HfCl2[N(SiMe3)(2)](2)) and water. The surface species was monitored during atomic layer deposition using vacuum chambers designed for in situ FT-IR spectroscopy studies. Vibrational spectroscopy reveals the gain and loss of surface species during the two surface half-reactions. The behavior of the functional group (such as O-H, Si-(CH3)(x), and C-H was monitored and from that, the temperature dependence of the growth rate and the film composition could be explained. It was also found that Si-O-Si peaks between 1000 and 1200 cm(-1) were formed when water was dosed above 300degreesC, which could explain the incorporation mechanism of Si into the film. (C) 2004 American Vacuum Society.