Effects of Poly-Si Grain Boundary on Retention Characteristics under Cross-Temperature Conditions in 3-D NAND Flash Memory.

Electrical characteristics with various program temperatures ( T PGM ) in three-dimensional (3-D) NAND flash memory are investigated. The cross-temperature conditions of the T PGM up to 120 °C and the read temperature ( T READ ) at 30 °C are used to analyze the influence of grain boundaries (GB) on the bit line current ( I BL ) and threshold voltage ( V T ). The V T shift in the E-P-E pattern is successfully decomposed into the charge loss (Δ V T,CL ) component and the poly-Si GB (Δ V T ,GB ) component. The extracted Δ V T ,GB increases at higher T PGM due to the reduced GB potential barrier. Additionally, the Δ V T ,GB is evaluated using the Technology Computer Aided Design (TCAD) simulation, depending on the GB position ( X GB ) and the bit line voltage ( V BL ).