Energy- and angle-dependent proton-induced single event upsets in FinFET circuits: impact of layout orientation and charge sharing

Abstract The increasing adoption of Fin Field-Effect Transistor (FinFET) circuits in space applications necessitates a thorough assessment of their susceptibility to proton-induced single event upsets (SEUs), given the dominance of protons in space radiation environments. While angular effects on heavy-ion-induced SEUs are well-documented, the synergistic energy- and angular-dependence of proton-induced SEUs remains insufficiently explored, particularly regarding layout orientation and charge-sharing dynamics. This work addresses these gaps through variable-angle proton irradiation experiments on advanced FinFET circuits, with underlying mechanisms elucidated via Monte Carlo simulations and a multi-scale Geant4-TCAD-SPICE synergistic framework. Results demonstrate distinct energy-dependent angular behaviors: at low proton energies, SEU cross-sections decrease monotonically with increasing incidence angle due to the Bragg peak shifting beyond the sensitive volume as effective overlayer thickness increases; at high energies, cross-sections initially rise owing to extended path lengths that promote nuclear reactions and secondary particle generation, then decline sharply beyond a critical angle because of reduced effective projected area. At the circuit level, the dense FinFET layout amplifies SEU sensitivity under oblique incidence parallel to fins via enhanced charge sharing among adjacent same-type transistors. In contrast, perpendicular incidence introduces opposing-polarity charge collection in PMOS-NMOS pairs, potentially suppressing upsets, though this effect is limited by large inter-transistor spacing and low charge-sharing probability. These findings identify worst-case proton testing scenarios and guide targeted radiation-hardening strategies: layout optimizations such as increased node separation or interleaving along the fin direction to decouple charge-sharing paths, and deep trench isolation to suppress parasitic bipolar amplification, thereby significantly enhancing the radiation tolerance of next-generation space electronics.