Semiconductor memory device and operating method thereof

A method of operating a semiconductor memory device, comprising:

• applying a program pulse to selected memory cells among a plurality of memory cells;
• continuously performing first and second verification operations using different first and second verification voltages;
• and
• when it is determined that the first verification operation has failed, continuously applying new program pulses obtained by increasing a previously applied program pulse by a step voltage and two times of the step voltage to the selected memory cells, and then re-performing from the first and second verification operations.

A method of operating a semiconductor memory device, comprising:

• applying a program pulse to selected memory cells among a plurality of memory cells;
• continuously performing first and second verification operations using different first and second verification voltages;
• and
• when it is determined that the first verification operation has failed, continuously applying new program pulses obtained by increasing a previously applied program pulse by a step voltage and two times of the step voltage to the selected memory cells, and then re-performing from the first and second verification operations,
• wherein after the applying of the program pulse, a discharge operation and a precharge operation of a bit line electrically coupled to the selected memory cells are performed before performing the first verification operation, and
• the discharge operation and the precharge operation of the bit line are skipped when the first verification operation is completed and then the second verification operation is performed.