 ion induced single event upsets. 6.3.3 Mitigation of Charge Generation and Collection [Marshall95'] [Marshall952][Mitsubishi99] The traverse of energetic charged particles produces charge which is collected on circuit nodes, resulting in Single Event Transients (SET) and Upset (SEU). An ability to attenuate the generation of charge and to reduce the amount of collected charge serves to increase the LET of the particle required to produce SEU and to reduce the cross section of the device, both resulting in decreased SEU rates. Techniques directed at reducing collected charge typically rely on the ability to truncate the funnel dimensions and to reduce the carrier lifetime in the region below the sensitive volume. The use of insulating material for device isolation instead of reverse biased junction isolation results in reduced charge generation. Commercial manufacturers have demonstrated success in the reduction of alpha particle induced soft error rate through the use of retrograde well profiles. The increasing carrier concentration with increased distance into the well region results in reduced carrier lifetime and hence less charge collected from the region below the sensitive volume. Using a technique which incorporates reduction in charge collection through the use of thin epi and a buried layer below the sensitive volume and mitigation of circuit response by increasing critical charge, Mitsubishi reports mitigation of alpha particle soft errors and effective attenuation of terrestrial neutron induced upsets. A technique explored for the gallium arsenide (GaAs) HIGFET structure indicates that significant reduction in the cross section of devices could be realized from high particle fluence bombardment. The non-ionizing energy deposited in the structure serves to reduce carrier lifetime in the substrate through formation of recombination sites, which affects the backgating and bipolar mechanisms which are believed to dominate in GaAs FET devices. Reduction in device cross section by an order of magnitude was 