Deposition of silicon oxide thin films in TEOS with addition of oxygen to the plasma ambient: IR spectra analysis

Silicon oxide thin films deposited on Si substrates in a RF-plasma CVD reactor, using Si(OC2H5)(4) (TEOS) as the precursor and oxygen as the gas ambient, were studied by IR spectrophotometry. All depositions were performed at a substrate temperature of 200 degrees C, a plasma power of 20 or 80 W and with a DC-bias of -120 V applied to the Si substrate. The observed IR peaks were assigned to corresponding vibrational modes. Peaks related to Si-H, C-H and OH bond vibrations were also detected. Some degree of porosity exists, resulting in a lower refractive index of the films than that typical for SiO2 material.