Modeling of the impact of elliptical shapes on main Read Window Budget mechanisms in 3D NAND

Accurately predicting the Read-Window-Budget (RWB) of a NAND array with complex-shaped cell transistors using TCAD is challenging due to limitations in handling the distribution of the entire array. In this study, we propose a novel method that integrates TCAD results with in-line physical characterization to investigate the impact of pillar shape on VT distribution, primarily at the block level. Additionally, we introduce a method to derive degradation mechanisms using large and small circle parallel circuit paradigm. The effectiveness of these approaches is validated by comparing the Read Disturb predicted by simulations with the shape dependence observed in Si data. By confirming the shape dependence of the main RWB degradation components, including Read Disturb, Program Disturb, Cell-to-Cell Interference, we demonstrate the feasibility of predicting RWB degradation by means of identified degradation mechanisms and a straightforward approach even for cell transistors with complex shapes.