Mechanical Stress and Electrical Properties of MNOS Devices as a Function of the Nitride Deposition Temperature

Abstract

The mechanical stress in memory quality silicon nitride films, the lattice parameter in the silicon substrate, the index of refraction, the dielectric constant of the films, and the saturation shift of the flatband voltage under positive and negative gate voltages in MNOS devices (as a function of the nitride deposition temperature) were studied in conjunction with the fixed interface charge density after fabrication. The nitride layers were deposited by the reaction of and on [111] and [100] silicon in the temperature range from 640° to 910°C. No significant dependence of the properties on deposition rate and substrate orientation was found. Index of refraction, dielectric constant, film stress, substrate lattice parameter, and the maximum shift of the flatband voltage show a common characteristic variation with deposition temperature, with a minimum between 710° and 760°C. The relationship of the structural and electrical properties is discussed.