A characterization model for ramp-voltage-stressed I-V characteristics of thin thermal oxides grown on silicon substrate

Abstract

A theoretical model considering the effects of Fowler-Nordheim tunneling, image-force lowering, first-order trapping kinetics and impact ionization has been developed to characterize the ramp-voltage stressed current-voltage characteristics of thin oxides grown on silicon substrate. Based on the developed model, physical parameters of thin oxides such as effective total trapping density, trap capture cross section, recombination capture cross section and dielectric breakdown field can be extracted from the measurements. In general, the dielectric field strength of the oxide can be enhanced by increasing the amount of traps, which is especially important when the effective total trapping density is above 10 13 cm −2. Besides, smaller leakage current across thin oxide can be obtained with larger effective total trapping density and trap capture cross section. The recombination capture cross section is found to be in the order of 10 −15–10 −14 cm 2 for thin SiO 2 ranging from 92 to 196 Å. The dielectric field strength is enhanced and the leakage current is reduced as the trapped electron centroid shifts toward the cathode electrode, however, this is less prominent when the effective total trapping density is ⩽10 12 cm −2.