The phenomenology of dielectric breakdown in thin silicon dioxide films: Al cathodes and p-type Si anodes

Abstract

Various aspects of the phenomenology of dielectric breakdown in Al-SiO2-p-Si metal-oxide-semiconductor planar capacitor structures have been investigated.The different types of breakdown events and their distributions are discussed in light of breakdown data from constant current stress tests and linearly ramped voltage tests with variable ramp rates. Many tests were performed on a wide variety of samples using Weibull-type distribution functions in analyzing the data. Of special interest was the influence of substrate parameters, such as oxygen concentration, surface transition-metal contamination, surface roughness, and the relatively simple surface defects which can form during a single oxidation treatment. Using very careful methods, three general types or ‘‘modes’’ of breakdown distribution are observed, a mode being defined as a subset of the complete distribution exhibiting the same or similar time and field parameters in the Weibull distribution. Two of the distinct modes are related to distributed ‘‘weak spots.’’ The third is apparently ‘‘intrinsic.’’ Implications for device reliability are considered. The origin and elimination of the distributed weak spot modes is discussed as are details of the intrinsic mode.