MULTI-LEVEL NONVOLATILE MEMORY AND METHOD OF PROGMMING THREROF

摘要

A programming method of a nonvolatile memory device programs memory cells into a multi-level through at least two programming steps. The method comprises pre-programming memory cells, into a level higher than a removal level and lower than a first target level, with the largest threshold voltage variation after and before programming by interworking with a programming operation of memory cells programmed from the removal level to one or more first target levels in a first programming step; and programming the memory cells pre-programmed in a second program step from the pre-programmed level to a next target level. Therefore, a threshold voltage difference after and before programming is reduced so as to minimize effects due to word line coupling and reduce distribution distortion and reading errors.