A Compact Model-Based Threshold Voltage Distribution Simulation of 3D Gate-All-Around (GAA) NAND Flash Memories
Jinil Yoo, Hyungcheol Shin · 2024
A new simulation method rather than a pure statistical Monte-Carlo method is developed to model a threshold voltage distribution shift of a NAND Flash memory during ISPP process. A random, normally distributed cell variation is applied to the electrostatic solutions of a single memory cell, and parallel computation is conducted for each cell which includes the compact model and carrier injection statistics. Width of $V_{t}$ distribution has fastly decreased at first several steps due to partial injection among total cells, and increased again since when program voltage is high enough. Field feedback became a dominant factor at final few steps, by reducing the width of distribution. The time-varying change of carrier concentrations is also investigated through the compact model-based simulations.