Mimicking program verify drain resistance in a memory device

摘要

A selected word line is biased with a program verify voltage. A predetermined quantity of unselected word lines that are between the selected word line and the bit line are biased with a modified V_pass voltage that is determined in response to a predetermined drain resistance. In one embodiment, the predetermined quantity is all of the word lines. Other embodiments can use smaller quantities. The remaining unselected word lines are biased with a normal V_pass voltage. The modified V_pass changes the resistance of the memory cells, acting as pass-gates during the program verification operation, to mimic a resistance of already programmed memory cells.