US Patent 7417899 Method of verifying flash memory device

A method of verifying a flash memory device includes discharging memory cell strings respectively connected to an even bit line and an odd bit line. Next, a voltage is applied to the memory cell strings respectively connected to the even bit line and the odd bit line, thus precharging the memory cell strings. The memory cell string connected to the even bit line are verified as erased by sensing the status of each memory cell string connected to the even bit line, and the memory cell string connected to the odd bit line are verified as erased by sensing the status of the memory cell string connected to the odd bit line.