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 SiOx/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 (tBD) 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.