Preparation and characterization of HfO2 thin films by photo-assisted MOCVD

High-k dielectric HfO2 thin films have been prepared by photo-assisted metal-organic chemical vapor deposition (MOCVD). Vacuum ultraviolet (VUV) light is used for enhancement of chemical reaction of the source materials of (Hf(O-t-C4H9)(4)) (HTB) and H2O. The absorption spectrum of HTB has been calculated with molecular orbital method. The calculated infrared absorption of HTB is found in VUV region (around 150nm), and WO, thin films were deposited under the irradiation with VUV light of a D-2, lamp including the HTB absorption band. These prepared films are characterized by FT-IR measurement to estimate the concentration of organic impurities. It shows that C-H peak drastically decreases less in the photo-assisted MOCVD film than the MOCVD. Moreover, C-V characteristics show that accumulation capacitance is increased in the film deposited under VUV irradiation. The accumulation capacitance is much increased by rapid thermal annealing (RTA) in the case of photo-assisted MOCVD. AFM observation results show that very smooth surface is obtained in the photo-assisted MOCVD films.