Preconditioning of defective and redundant columns in a memory device

摘要

A redundant column is mapped to a defective or over-erased column in the memory array. When an erase command occurs, both the redundant column and the defective or over-erased column are preconditioned by preprogramming them. The defective or over-erased column is preprogrammed and verified a predetermined number of times or until the verification passes. The redundant and defective or over-erased columns are then erased with the rest of the memory block.