Low temperature SiO 2 films

Abstract

Silicon dioxide films have been deposited by the plasma-enhanced chemical vapour deposition technique using silicon halides (SiCl 4 and SiF 4) and O 2 or N 2O as reactive materials. In the case of SiF 4 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 SiO 2 at 1070, 800 and 450 cm −1. No absorption peaks related to SiOH or SiH were observed. In the case of SiF 4 films a small absorption peak due to SiF at 930 cm −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 SiCl 4 oxides. For SiF 4 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 Å 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.