Publications Details
A critical examination of charge funneling and its impact on single-event upset in Si devices
Low-energy alpha particles emitted from packaging and high-energy heavy ions in space possess the capability of causing changes in memory state when incident on semiconductor memory cans and latch circuits. This phenomenon of single-event upset (SEU) is caused by collection of charge created as the particle travels through a sensitive volume of the device. As devices are continually down-sized, the corresponding decrease in amount of charge held on storage nodes increases device susceptibility to SEU. Solutions to harden devices to SEU require an in-depth understanding of the basic mechanisms responsible for upset. Also, a detailed understanding of the charge-collection volume is critical for predicting on-orbit error rates. Previous work has revealed the formation of a field funnel in response to the particle strike. Analytical models that treat the funnel in a time-averaged sense have been developed, and have been reasonably successful at predicting total collected charge for particles with low linear energy transfer (LET). Sophisticated two- and three-dimensional simulations have been used to investigate the funneling process more rigorously; however, the interplay between the funnel and collection by drift and diffusion has remained somewhat obscure. In this paper, we present an examination of fundamental charge-collection mechanisms and the role of the funnel, using advanced three-dimensional drift-diffusion modeling. We then apply the insight gained to address radiation hardness issues in light of current technology trends.