LOW-TEMPERATURE SIO2-FILMS

Silicon dioxide films have been deposited by the plasma-enhanced chemical vapour deposition technique using silicon halides (SiCl4 and SiF4) and O2 or N2O as reactive materials. In the case of SiF4 and H-2 flow was also added to the mixture of reactive gases. Infrared transmittance, ellipsometry and electrical measurements have been used to characterize the films. Also, the chemical etching rate with a "P etch" solution was used to characterize the films. The IR percentage transmittance of the films shows the absorption peaks of SiO2 at 1070, 800 and 450 cm-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 930 cm-1 is present when a low H-2 flow is used. At higher H-2 flows this peak decreases and eventually disappears. The refractive index was 1.468 +/- 0.005 for SiCl4 oxides. For SiF4 films it was in the range 1.445-1.46, depending on the deposition conditions. The etching rate of the film was in the range of 5-11 angstrom min-1. The oxides incorporated in a metal-oxide-semi-conductor structure show good capacitance vs. voltage characteristics and the current vs. voltage curves indicate good insulating properties up to 4 MV cm-1.