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.