Compact Modeling of Variability Effects in Nanoscale NAND Flash Memories

This paper presents a thorough investigation of the main variability effects in nanoscale NAND Flash memories, considering their impact on device operation by means of a statistical compact model for the memory array. The compact model allows the accurate simulation not only of the NAND string current in read conditions, including parasitic capacitive couplings among neighboring cells, but also of cell program and erase. Changing the model parameters to account for their physical fluctuation in a Monte Carlo fashion, the impact of each variability source on the statistical dispersion of both neutral and programmed cell threshold voltage is obtained for state-of-the-art and next-generation technology nodes. The good agreement between modeling and experimental results and the low computational load make the proposed methodology a valid solution for the assessment of variability constraints on NAND technology design.