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 ch emical vapor deposition from silane SiH4 and ammonia NH3 at high temperatur e (750 degrees C) and the influences of the NH3/SiH4 gas ratio on the films deposition rate, refractive index, stoichiometry, microstructure, electric al conductivity, and thermomechanical stress are studied. The chemical spec ies derived from silylene SiH2 into the gaseous phase are shown to be respo nsible for the deposition of NIDOS and/or (silicon rich) silicon nitride. T he competition between these two deposition phenomena leads finally to very high deposition rates (approximate to 100 nm/min) for low NH3/SiH4 gas rat io (R approximate to 0.1). Moreover, complex variations of NIDOS film prope rties are evidenced and related to the dual behavior of the nitrogen atom i nto silicon, either n-type substitutional impurity or insulative interstici al impurity, according to the Si-N atomic bound. Finally, the use of NIDOS deposition for the realization of microelectromechanical systems is investi gated. (C) 2000 American Vacuum Society. [S0734-2101(00)04505-X].