Analysis of Channel Potential Recovery According to the Back Pattern in 3D NAND Flash Memory

Abstract

This study analyzed the recovery of channel potential according to the program states of adjacent cells. When the verify operation ended, and all voltages dropped to 0 V and the decreased potential of the floating channel caused by the down-coupling phenomenon was recovered continuously over time, regardless of the program states of adjacent WLs. The extent of channel potential recovery showed a similar tendency to that of the variation in the electron concentration of the floating channel. The electron–hole pair recombination decreased the electron concentration, resulting in channel potential recovery. When the adjacent WLs were programmed in a low state, additional electron–hole pair recombination and hole diffusion occurred in the floating channel. Therefore, the channel potential recovered quickly when the adjacent WLs programmed in a low state compared to when they programmed in a high state.

Keywords

• 3D NAND flash memory
• channel potential
• down-coupling phenomenon (DCP)
• electron-hole pair recombination
• carrier diffusion
• TCAD