Surface characterization of thin silicon-rich oxide films

The silicon-rich oxide (SiO x ) films were deposited using the LPCVD (Low Pressure Chemical Vapour Deposition) method at the temperature of 570 °C and with silane and oxygen as the reactant gasses. The films were deposited on silicon (1 1 1) substrates. The flows of oxygen and silan in the horizontal tube reactor were varied in order to deposit films with different values of oxygen content x. The roughness of the film surfaces and of the substrate-film interfaces were determined by X-ray specular reflection. A homogeneous surface with the root-mean square (r.m.s.) surface roughness less than 3 nm has been found. Scanning electron microscopy shows surface lateral structures smaller than 50 nm. Infrared absorption shows the broad peak of the TO 3 phonon mode at 1000 cm −1 which blue shifts with the increase of oxygen content x. The observed absence of the LO 3 phonon mode at 1260 cm −1 is an another indication of the low surface roughness. The Raman spectra show broad bands of the TA, LA, LO, and TO-like phonon bands typical of amorphous materials.