Patent ID: 7715238

Claim:
A method of operating a non-volatile memory device, the method comprising: performing a first program operation by applying a first program voltage to word lines of memory cells, constituting a memory block, and measuring threshold voltages of the memory cells as a result of the first program operation; performing a second program operation using a second program voltage that is increased as much as a difference between a first threshold voltage, that is, a lowest voltage level of the measured threshold voltages and a second threshold voltage, that is, an intermediate voltage level of the measured threshold voltages; and repeatedly performing the second program operation by increasing the second program voltage by as much as the difference between the first and second threshold voltages until the lowest threshold voltage becomes higher than a program verify voltage, and setting a pass voltage by reflecting a first voltage level, that is, a difference between a program voltage applied in a last program execution step and the first program voltage.