Infrared study of Si surfaces and bonded Si wafers

Attenuated total reflection (ATR) spectra of hydrophobic and hydrophilic Si wafers, Si wafers with thermally grown SiO2 layers and bonded Si wafers we re investigated. It was found that the surface of the as-prepared hydrophob ic wafer is terminated by hydrogen and water molecules while the IR spectra of the hydrophilic wafer demonstrate only the presence of water molecules at the surface. ATR spectra of Si wafers covered by a thermally grown SiO2 layer exhibit a number of the strong absorption bands. The analysis of ATR spectra and the single-transmission spectra allows these modes to be assign ed to combinational phonon bands in SiO2. The use of a double-bonded Si str ucture allows the influence of the outer surfaces to be excluded. The wafer bonding leads to the appearance of siloxane and hydroxyl groups at the bur ied interface whose absorption bands were observed in ATR spectra.