Reducing hot electron injection type of read disturb in 3d non-volatile memory

Abstract

Read disturb due to hot electron injection is reduced in a 3D memory device by controlling the magnitude and timing of word line and select gate ramp down voltages at the end of a sensing operation. In an example read operation, the magnitude of a selected word line voltage is increased to be equal to pass voltages of unselected word lines, and the selected and unselected word line are ramped down at the same time, to avoid creating a channel gradient. In an example verify operation, the above procedure can be followed when the selected word line is at a source-side or middle range among all word lines. When the selected word line is at a drain-side among all word lines, a source-side select gate can be ramped down before the selected word line and a drain-side select gate can be ramped down after the selected word line.