Deposition of High-Quality SiO₂ Insulating Films at Low Temperatures by means of Remote PECVD

Silicon dioxide films were deposited by means of remote inductively coupled plasma enhanced chemical vapor deposition (ICPECVD) in Ar-N2O-SiH4 plasma at 150 °C and pressures between 1 and 6 Pa. The gas phase contained 0.08% of SiH4 and 18% of N2O. We observed that, at a total pressure of 1 Pa, the oxide films were formed with a density equal to that of thermally grown oxide. The films had a low oxide charge. Deposition at higher pressures resulted in the formation of oxides having a lower density than the film deposited at 1 Pa, and a higher oxide charge. We measured a strong dependence of the oxide charge on the film thickness. The films deposited at 1 Pa further exhibited leakage currents at an electric field strength of 6.5 MV/cm which were comparable to the leakage currents known for thermally grown (1000°C) oxides. The film deposited at 2 Pa also exhibited a low leakage current, but the current increase was observed at lower electric fields compared to the 1 Pa film. The films deposited at 6 Pa exhibited significantly higher leakage currents.