Based on a chemical mechanism whose reliability has already been established;in a previous paper, two-dimensional models for some normally employed reactors, namely, longitudinal flow, radial flow and showerhead reactors were developed in the case of silicon nitride plasma enhanced chemical vapor deposition (PECVD) from silane and ammonia mixtures. The aim of this study was to gain a new and global insight into the understanding of the overall behavior of PECVD reactors which can be useful for reactor developers and users. In this work, the reactor design and the flow distribution were shown to be determining parameters. Apart from some second-order differences, some general tendencies were brought to the fore and two groups of reactors were distinguished : the ’localized injection reactors’ and the ’distributed injection reactors’. In the case of the first type, the deposition rate and film composition undergo variations which can be strong, whereas in the other, the thickness uniformity and the composition uniformity of the layer are very satisfactory, even for large-size reactors. This last type of reactors was found to be all the more interesting as the film composition could be set by choosing appropriate operating conditions.