Physical Model and Characteristics of 3D NAND Memory Cell Metastability Issues under High Temperature Stress

A new memory device behavior has been experimentally identified and investigated in 3D NAND devices. The experimental results show that the memory device characteristics pertaining to channel properties are degraded through hightemperature stress and can be subsequentially annealed depending upon the Vt level of the cell. This newly identified NAND memory cell metastability issue is characterized and the mechanism is identified as an increase in polysilicon trap density from alternate bonding configurations within the channel film/interfaces post hydrogen passivation.