Investigation of Inhibited String Characteristics According to Dimple Structures in 3D NAND Flash Memory
Jesun Park, Myounggon Kang · IEEE Electron Device Letters · 2025
In this letter, we investigated the boosted channel potential (V$_{\mathbf {\textit {ch}}}$) in inhibited strings with dimple (concave and convex) structures and analyzed the program (PGM) disturbance caused by$V_{\mathbf {{ch}}}$. In concave structures, the electric field (e-field) concentrated in the spacer (SP) region, resulting in a decrease in V$_{\mathbf {\textit {ch}}}$as the degree of concavity increases. In convex structures, the e-field concentrates in the center of the word line (WL) region, boosting$V_{\mathbf {{ch}}}$as the degree of convexity increases. This occurs due to the dispersion or concentration of the PGM voltage applied to the WL. High V$_{\mathbf {\textit {ch}}}$in the selected WL increases the potential difference ($\Delta $V$_{\mathbf {\textit {ch}}}$) between adjacent WLs. Due to structural characteristics, the lateral e-field (E$_{\mathbf {m}}$) is largest in concave structures, whereas the vertical e-field (E$_{\mathbf {\textit {ox}}}$) dominates in convex structures. Consequently, PGM disturb characteristics caused by hot carrier injection (HCI) are significantly degraded in convex structures.