a of [206], although the qualitative trend was similar. As noted by the authors, these differences due to processing make it difficult to conclusively establish whether in the future SEGR will be a problem for a particular technology operating at a specific oxide thickness and power supply voltage. It does appear, however, that the pre- irradiation dielectric breakdown field strengths are a reliable indicator of relative SEGR vulnerability. Regardless of processing technology, the published data all confirm that for a given oxide thickness, the higher the pre-irradiation breakdown field, the higher the critical field to SEGR [206,208,209]. Clearly there are some technologies where the critical field to SEGR is in the range of 5-6 MeV/cm, at least for high LET ions. Whether SEGR will in fact be a problem in the future depends on many factors, including what voltage scaling trends are actually adopted and if alternative dielectric materials are used [208]. Recent work has probed not only scaling trends, but also the underlying mechanisms for SEGR in thin gate oxides [208,209]. Based on a limited amount of data for varying ion fluences, earlier work suggested that multiple ion hits might be necessary to initiate SEGR [207]. More extensive data gathered since then conclusively show that there is at most a small effect of fluence per irradiation step on the SEGR threshold. Figure 4.6 shows the critical voltage to rupture measured in capacitors with a 7-nm oxide as a function of the number of ions received per irradiation step [209]. There is only a very weak dependence: 15% difference in critical II-40 voltage to SEGR over more than three orders of magnitude of fluence per step. Two pre-stress points are also marked on the plot. For these two points, capacitors were pre-stressed at zero bias with a fluence of 2x108 ions/cm². Even after this enormous pre-stress+, the voltage to rupture remained unchanged. These data strongly support a true single-ion model for gate rupture [209]. Although SEGR appears to be a true sing