Turnaround in the temperature dependence of RTN in 3D NAND arrays entering the cryogenic regime

In this letter, we report clear experimental evidence of the existence of a turnaround in the temperature dependence of RTN in 3D NAND Flash memories, showing up when entering the cryogenic regime. The origin of this phenomenology is traced back to the change of the dominant transport mechanism through the grain boundaries of the polysilicon channel of the memory cells, from thermionic emission to quantum-mechanical tunneling. This change decreases the impact of the charging/discharging of microscopic defects at the grain boundaries on cell current, making RTN in the cryogenic regime much more bearable than what expected from the extrapolation of room temperature data.