FT-IR-ATR study of depth profile of SiO2 ultra-thin films

It is very important to characterize the depth change in chemical bonding s tructures of ultra-thin SiO2 films. The LO mode and the lower frequency sho ulder peak of SiO2 on Si was detected by the FT-IR-ATR method, and this ban d was simulated by a gradient layered and effective medium model. Interface roughness estimated from the shoulder bands of ATR spectra was in good agr eement with the GIXR results, and the shoulder band also reflects the chang e of Si-O-Si bonding angle. In our calculation, the shoulder band around 11 50-1050 cm(-1) reflects the interface roughness and the shoulder band aroun d 1250-1150 cm(-1) includes information about the change of Si-O-Si bonding angle and/or Si-O force constant. The FT-IR-ATR method is a useful techniq ue with which to characterize SiO2 ultra-thin films. (C) 2001 Elsevier Scie nce B.V. All rights reserved.