US Patent 9620221 Semiconductor memory device and operating method thereof

There may be provided a semiconductor memory device and an operating method thereof. A semiconductor memory device may include a memory cell array including a plurality of memory strings. The semiconductor memory device may include a peripheral circuit for performing a program operation on the plurality of memory strings, and a control logic for controlling the peripheral circuit to perform the program operation. The control logic may control the peripheral circuit to adjust potential levels of program permission voltages to be applied to the plurality of memory strings according to arrangement positions of the memory strings.