Effects of EUV Irradiation on Poly-Si SONOS NVM Devices
The effects of extreme-ultraviolet (EUV)-irradiation- induced damage on the characteristics of a silicon-oxide-nitride- oxide-silicon (SONOS) memory device are investigated. After EUV irradiation, changes in the memory window and program/ erase speed indicate the generation of positive charges and new traps. Retention performance degrades after high-dose irradia- tion, which indicates that the tunneling layer is damaged. En- durance performance degrades severely because the damage in the blocking oxide results in serious electron back injection after cycling operations. These defects cannot be recovered after 600 ◦ C annealing. It is recommended that in-process high-dose EUV irra- diation on a SONOS stack after a front-end-of-line process should be avoided.