Single-Event Upset Cross-Section Trends for D-FFs at the 5-and 7-nm Bulk FinFET Technology Nodes

At each advanced technology node, it is crucial to characterize and understand the mechanisms affecting performance and reliability. Scaling for all nodes prior to the 5-nm bulk FinFET node had resulted in a decrease in single-event upset (SEU) cross section at each node. However, this trend unexpectedly reversed for scaling from the 7-nm bulk FinFET node to the 5-nm bulk FinFET node. Experimental results show that the SEU cross sections for D flip-flops (D-FFs) designs at the 5-nm node are greater than those at the 7-nm for the whole range of particle linear energy transfer (LET) values tested. The 3-D technology computer-aided design (TCAD) and circuit-level simulations show that the increase in single-event (SE) cross Section with scaling to the 5-nm node is due to interactions between changes in drive current and nodal capacitances. The relative changes in these parameters increased SE transient (SET) pulsewidths and decreased feedback-loop delays, resulting in an increase in SE cross sections for the 5-nm node. In addition, the effects of threshold voltage and supply voltage on SEU cross section for both the 5- and 7-nm nodes are investigated. The SEU cross section for the D-FF designs at the 5-nm node shows a stronger dependence on both threshold voltage and supply voltage than that for the 7-nm node. As critical charge decreases with scaling, small differences in critical charge become more significant and manifest as large changes in SEU cross section, as observed for the 5-nm node. Designers will need to be particularly careful in assessing the overall SE susceptibility of systems developed using the 5-nm bulk FinFET node, particularly when different threshold voltage options and supply voltages are used across the IC.