I. Introduction
The nand Flash device has been widely used in nonvolatile memory cells due to its high density, low cost, and low power consumption. When the cell array is shrinking, the issues of neighbor floating-gate (FG) coupling and interface state generation in the corner region of the transistor become more severe [1]. To solve the FG–FG coupling issue, using a deep control gate (CG) to shield the coupling effect is one common method. A deep CG structure improves not only the FG–FG coupling issue but also the gate coupling ratio (GCR). Because the deep CG structure is close to the corner region of the transistor, the characteristics such as electron density and electric field near the corner region of the transistor are greatly affected by the bias applied to CG [2]. Such a “CG-modulated corner effect” is utilized for the first time to analyze the located in the corner region in this study.