Conduction and trapping mechanisms in SiO₂ films grown near room temperature by multipolar electron cyclotron resonance plasma enhanced chemical vapor deposition

Silicon dioxide layers with stoichiometric composition and excellent electrical properties were deposited at a substrate temperature of 60 degreesC with an electron cyclotron resonance plasma source. This work is focused on determining the electrical conduction and trapping mechanisms of the deposited films. From the temperature dependence of current density-electric field characteristics, Fowler-Nordheim tunneling was found to be the dominant conduction mechanism in SiO2 films obtained with low silane flow and at low pressure. For layers deposited with higher silane flows and higher pressures, the current at low biases is highly dependent on temperature. Positive charge was measured at the Si/SiO2 interface during low electric stress, while electrons were trapped at the interface for electric fields higher than 7 MV/cm. Constant current stress measurements confirmed that low silane flow and low total pressure are suitable deposition conditions for obtaining a film comparable to thermally grown oxide from the reliability point of view.