High density plasma deposition of device quality silicon nitride. II. Effects of thickness on the electrical properties

Dielectric behavior of SiNx films, fabricated by microwave electron cyclotr on resonance discharge, has been studied as a function of film thickness on the basis of the current-voltage and the capacitance-voltage characteristi cs. In the thickness range (20 nm<d<80 nm), the resistivity and the critica l field for SiNx were found not to be sensitive to the film thickness (cl) and which was opposite to strong dependence of the dynamic dielectric const ant epsilon(d) on thickness. To explain the epsilon(d) behavior as a functi on of d, a model based on trapped space charge effects is proposed. The dom inant mode of electronic conduction, determined from J-E-1/2 curves and Arr henius plots of leakage current, appears to be Poole-Frenkel emission only for thicker films (d>20 nm). Finally, the spatial profile of fixed charges reveals that SiNx/Si interface has a much greater concentration of defects than the bulk film. (C) 1999 American Vacuum Society. [S0734-211X(99)00704- 0].