Properties of nitrogen doped silicon films deposited by low-pressure chemical vapor deposition from silane and ammonia

Nitrogen doped silicon (NIDOS) films have been deposited by low-pressure chemical vapor deposition from silane $SiH4$ and ammonia $NH3$ at high temperature (750 °C) and the influences of the $NH3/SiH4$ gas ratio on the films deposition rate, refractive index, stoichiometry, microstructure, electrical conductivity, and thermomechanical stress are studied. The chemical species derived from silylene $SiH2$ into the gaseous phase are shown to be responsible for the deposition of NIDOS and/or (silicon rich) silicon nitride. The competition between these two deposition phenomena leads finally to very high deposition rates (≈ 100 nm/min) for low $NH3/SiH4$ gas ratio $(R≈0.1).$ Moreover, complex variations of NIDOS film properties are evidenced and related to the dual behavior of the nitrogen atom into silicon, either n-type substitutional impurity or insulative intersticial impurity, according to the Si–N atomic bound. Finally, the use of NIDOS deposition for the realization of microelectromechanical systems is investigated.