Mechanisms of Single-Event Displacement Damage in Silicon FinFET SRAM Cells

Monte Carlo radiation transport techniques, Molecular Dynamics (MD), and Technology Computer-Aided Design software (TCAD) are collectively employed to investigate the mechanisms of Single-Event Displacement Damage (SEDD) failures in highly-scaled CMOS devices. Building off the well-established Monte Carlo Radiative Energy Deposition code (MRED), a two-stage, atomic-scale MD framework is employed to better understand how SEDD correlates to Non-Ionizing Energy Deposition (NIED) by accounting for vacancy generation profiles and diffusion. This higher-fidelity method is used to evaluate the modified Kinchin-Pease (KP) approximation for the purposes of SEDD. MD results reveal wider distributions of damage than those from MRED & KP alone. These variances must be accounted for in hardness assurance protocols for highly scaled CMOS. TCAD simulations indicate defects cause SRAM cell failure via scattering processes, manifesting as a stuck bit. The combined results of these simulations are consistent with accumulated displacement damage failure rate predictions using MRED & KP alone but suggest a different damage threshold than previous methods would show. The combined-model results are consistent with TCAD simulations of device failure. This discrepancy emphasizes the need to account for material damage mechanisms in calculations of NIED and will become more apparent for simulations of SEDD in highly scaled devices.