Effect of Lateral Charge Diffusion on Retention Characteristics of 3D NAND Flash Cells
Ho-Nam Yoo, Bongsik Choi, Jong-Won Back, Ho-Jung Kang, Eunmee Kwon, Sungyong Chung, Jong‐Ho Bae, Byung‐Gook Park, Jong‐Ho Lee · IEEE Electron Device Letters · 2021
Retention characteristics of 3D NAND Flash cells are investigated at various temperatures ( T) depending on the degree of program and erase. The ΔVthfor each condition is compared to understand the degradation of the retention characteristics attributable to vertical loss and/or lateral diffusion. In addition, the relationship between Program/Erase (PE) window (PGM Vth- Erase Vth) and ΔVthare analyzed. In the case when PGM Vthis the same, the ΔVthdecreases as the PE window decreases. At temperatures below 150 °C, ΔVthand PE window show linear relationship, and as PE window decreases, ΔVthalso decreases to 0. On the other hand, at 250 °C, ΔVthhas a non-zero value even if PE window decreases to 0, thus has a non-linear relationship. The measurement results show that the lateral diffusion has a great influence on the short-term retention of 3D NAND flash cells.