Erase For 3D Non-Volatile Memory With Sequential Selection Of Word Lines

摘要

An erase operation for a 3D stacked memory device adjusts a start time of an erase period and/or a duration of the erase period for each storage element based on a position of the storage element. A voltage is applied to one or both drive ends of a NAND string to pre-charge a channel to a level which is sufficient to create gate-induced drain leakage at the select gate transistors. With timing based on a storage element's distance from the driven end, the control gate voltage is lowered to encourage tunneling of holes into a charge trapping layer in the erase period. The lowered control gate voltage results in a channel-to-control gate voltage which is sufficiently high to encourage tunneling. The duration of the erase period is also increased when the distance from the driven end is greater. As a result, a narrow erase distribution can be achieved.