Non-volatile memory device and operating method thereof including a negative discharge voltage

Abstract

An operating method of a non-volatile memory device including a plurality of cell strings connected to a plurality of word lines, string select lines, and ground select lines includes applying a program voltage to a selected word line among the word lines during a program execution period, determining a discharge voltage by comparing the program voltage with a negative discharge reference voltage during the program execution period, applying a precharge voltage, which is less than the program voltage and greater than the discharge voltage, to the string select lines up to a first time point during a verify period following the program execution period, and applying the discharge voltage to a substrate of a string select transistor, which is connected to an unselected string select line among the string select lines, up to a second time point after the first time point during the verify period.