Microscopic Analysis of Degradation and Breakdown Kinetics in HfO₂ Gate Dielectric after Ions Irradiation

We combine experiments and simulations to investigate the degradation dynamics and dielectric breakdown (BD) of SiO_x/HfO₂ gate stacks irradiated with varying doses of 40 MeV carbon ions. The analysis of postirradiation electrical characteristics (current-voltage, I-V, capacitance-voltage, C-V, and conductance-voltage, G-V) reveals that the HfO₂ layer is the most affected by irradiation-induced damage, leading to the formation of defects consistent with oxygen vacancies. Postirradiation constant voltage stress (CVS) experiments reveal an inverse dependence of time to breakdown (t_BD) and Weibull slopes (β) on the irradiation dose. These trends are accurately reproduced by statistical physics-based breakdown simulations only when accounting for partial percolation paths induced by ion strikes during irradiation, as well as a spatially correlated defect generation process during subsequent electrical stress. Our findings are crucial for designing radiation-hardened materials and improving the resilience of electronics operating in harsh environments.