Infrared spectra of photochemically grown suboxides and oxynitrides at the Si/SiO 2 interface

Abstract

Photoinduced growth of ultrathin silicon-oxide and silicon-oxynitride layers on Si(1 1 1) and Si(1 1 0) was studied at room temperature using F 2-laser irradiation (157 nm) in an O 2 or N 2O atmosphere. The appearance of Si–O, Si–N and N–O phonon bands in the 700–1400 cm −1 region was monitored by FTIR-transmission spectroscopy with monolayer resolution. The differences in the IR spectra for normal and oblique incidence of the analyzing IR beam are discussed. The IR and XPS spectra of the ultrathin silicon-oxide and silicon-oxynitride layers of ∼1 nm thickness indicate suboxide species (SiO x , x<2) in the transition region of several layers in the as-grown layers.