Cross section measurements and upset rate calculations

This paper discusses the information about device upset rates that is contained in the experimental heavy ion cross section curve. The width and shape of the curve are determined by intra-cell variations of charge collection, not by cell to cell variations, as previously believed, If we assume that there is a unique charge that must appear on the transistor terminal to cause upset, and if there is a unique charge deposition depth and volume, then the cross section curve is determined by variations of effective charge collection gain inside the device. The fraction of a cell that has a given charge collection gain can be determined from the parameters that describe the cross section curve. The gain probability can also be expressed in terms of the lognormal function. The cross section curve can be described in terms of the cumulative lognormal function. This three parameter approach appears to be an improvement over the four parameter Weibull description. The upset rate calculation can then be expressed in terms of an integration over the variation of gain as represented by the measured cross section curve.