LOW-TEMPERATURE SIO2-FILMS

Silicon dioxide films have been deposited by plasma-enhanced chemical vapour deposition technique using silicon halides (SiCl4 and SiF4) and O2 or N2O as reactive materials. In the case of SiF4 a hydrogen flow was also added to the mixture of reactive gases. IR transmittance, ellipsometry, and electrical measurements have been used to characterize these films. Also, the chemical etching rate with a "P" etch solution was used to characterize these films. The IR percentage transmittance of these films reveals the absorption peaks of SiO2 at 1070, 800 and 450cm-1. No absorption peaks related to SiOH or SiH were observed. In the case of SiF4 films a small absorption peak due to SiF at 930cm-1 is present when a low hydrogen flow is used. At higher hydrogen flows this peak decreases and eventually disappears. The refractive index was 1.468 +/- 0.005 for SiCl4 oxides. For SiF3 films, it was in the range 1.445-1.46, depending on the deposition conditions. The etching rate of these films was in the range 5-11 angstrom s-1. The oxides incorporated in a metal-oxide-semiconductor structure exhibit good capacitance vs. voltage characteristics and the current vs. voltage curves indicate good insulating properties up to 4 MV cm-1.