NONVOLATILE MEMORY DEVICE AND RELATED METHOD OF OPERATION

摘要

A method of programming selected memory cells to a plurality of target states comprises applying a first verification voltage to the selected memory cells to perform a verification read operation on memory cells programmed to at least one target state, applying a program voltage to the selected memory cells, and applying a second verification voltage lower than the first verification voltage to the selected memory cells to perform a verification read operation on memory cells programmed to the at least one target state, wherein the second verification voltage is provided in a specified program loop and subsequent program loops. The second verification voltage is set such that a number of slow bits in the at least one target state is different from the number of slow bits in another target state.