Surface characterisation of thin silicon rich oxide thin films

The silicon rich oxide (SiOx) films were deposited using the LPCVD (Low Pressure Chemical Vapour Deposition) method by thermal oxidation of silan in an oxygen atmosphere at the temperature of 570C. The films were deposited on silicon (111) 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 deposition temperature of 570C was chosen in order to obtain highly homogeneous thin films. The roughness of the film surfaces and of the substrate-film interfaces were determined by X-Ray specular reflection. The films were found to have a very homogeneous surface. Scanning electron microscopy was used to study the surface morphology of the thin films. Infrared absorption measurements of the thin films were made, and they showed the absence of the broad band at 1260 cm-1 in the infrared spectra, which is an indication of low surface roughness. Raman spectroscopy was used to determine the structure of the deposited films. The measured Raman spectra showed broad bands typical of the Raman spectra of amorphous materials.