Block data encryption of non-volatile memory through selective select gate erase through charge coupled scheme

Abstract

To allow for the erase of the drain side select gates of NAND strings while maintaining the data content of the memory cells, while erase inhibiting the memory cells of a NAND string, holes are generated in the drain region through the gate induced drain leakage (GIDL) mechanism and transferred to under the select gate, where they are then used to erase the select gate by Fowler-Nordheim mechanism. This allows for the refresh of the drain side select gates while retaining the data content of the NAND strings. This approach can also be used for data encryption, since, by erasing the drain side select gates, a block of data can be rendered unreadable; but, since the data content is not erased, it can later be recovered.