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 an 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 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 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 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 the films was in the range of 5–11 Å min -1. The oxides incorporated in a metal-oxide-semiconductor structure show good capacitance vs. voltage characteristics and the current vs. voltage curves indicate good insulating properties up to 4 MV cm -1.