The Effect of Heavy-Ion Strikes on Charge Trap Memory Arrays With Analog State Programmability

Single-event effects (SEEs) induced by heavy ions were characterized on 32 distinct conductance states in 40-nm silicon-oxide–nitride-oxide–silicon (SONOS) charge-trap memory. These states were programmed onto three chips, each containing 256K SONOS memory devices in an array that was optimized for analog in-memory computing (IMC) operations. Spatially resolved measurements of heavy-ion effects on analog states reveal that the energy deposited by an ion is distributed across multiple adjacent memory cells, inducing a smooth tail in the memory state distributions. Ion-induced state shifts also show a strong dependence on the electric field across the tunnel oxide. Following radiation, SONOS devices that were struck by heavy ions showed no evidence of permanent damage that led to any observable degradation in long-term data retention properties. This resilience is likely intrinsic to the charge storage mechanism in SONOS memory and helps enable its reliable use in space for both data storage and analog IMC applications.