Study of P/E Cycling Endurance Induced Degradation in SANOS Memories Under NAND (FN/FN) Operation

摘要

Program/Erase (P/E) cycling endurance in poly-$hbox{Si/Al}_{2} hbox{O}_{3}/hbox{SiN/SiO}_{2}/hbox{Si}$ (SANOS) memories is systematically studied. Cycling-induced trap generation, memory window (MW) closure, and eventual stack breakdown are shown to be strongly influenced by the material composition of the silicon nitride (SiN) charge trap layer. P/E pulsewidth and amplitude, as well as starting program and erase flatband voltage $({rm V}_{rm FB})$ levels (therefore the overall MW), are shown to uniquely impact stack degradation and breakdown. An electron-flux-driven anode hole generation model is proposed, and trap generation in both SiN and tunnel oxide are used to explain stack degradation and breakdown. This paper emphasizes the importance of SiN layer optimization for reliably sustaining large MW during P/E operation of SANOS memories.