Reliability of thermally oxidized SiO_2/4H-SiC by conductive atomic force microscopy

摘要

The dielectric breakdown (BD) kinetics of silicon dioxide (SiO_2) thin films thermally grown on 4H-SiC was determined by comparison between Ⅰ-Ⅴ measurements on large area (up to 1.96 x 10~(-5) cm~2) metal-oxide-semiconductor structures and conductive atomic force microscopy (C-AFM). C-AFM clearly images the weak breakdown single spots under constant voltage stresses. The stress time on the single C-AFM tip dot was varied from 2.5 x 10~(-3) to 1 x 10~(-1) s. The density of BD spots, upon increasing the stress time, exhibits an exponential trend. The Weibull slope and the characteristic time of the dielectric BD events have been determined by direct measurements at nanometer scale allowing to demonstrate that the percolative model is valid for thermal oxide on 4H-SiC.