Properties of Vapor Deposited Silicon Nitride Films with Varying Excess Si Content

Physical, chemical and electrical properties of Si rich silicon nitride (SiN) film deposited by using the SiH 4 –NH 3 system have been studied. By changing the volume ratio of NH 3 to SiH 4 from 100 to 1/30, samples with varying excess Si content within SiN films can be obtained. The current conduction mechanism of the SiN film can be represented by the superposition of Poole-Frenkel current, field ionization current and hopping current as reported by Sze in the Si 3 N 4 films without Si excess. Energy levels of trapping centers responsible for Poole-Frenkel current become shallow while their densities remain nearly constant as a function of the Si content. From the dependence of the shift characteristics of C – V curves, it has been deduced that the maximum charge storage within the SiN film is controlled by current conduction through the film.