| 摘要 |
PURPOSE: A semiconductor memory device and an operating method thereof increase cell current by measuring the cell current flowing in a cell string according to the number of program/erasure cycles, thereby stably sensing data. CONSTITUTION: An initial first cell current flowing in a cell string including memory cells is measured (S310). A second cell current flowing in the cell string is measured when the number of program/erasure cycles of the memory cells reaches the predetermined number (S350). The cell current flowing in the cell string is increased in a sensing operation of data stored in the memory cells when the ratio of the second cell current to the first cell current is less than a threshold value. [Reference numerals] (AA) Start; (BB,DD,FF) No; (CC,EE,GG) Yes; (HH) End; (S310) Measure the initial current of a cell (Io); (S320) Perform an E/W cycling process; (S330) Count the number of performing E/W cycling process; (S340) Is the number of performing E/W cycling process identical to a pre-determined number ?; (S350) Measure the current of the cell (Im); (S360) Is the value of dividing Im by Io less than or equal to a critical value ?; (S370) Increase the value of drain select voltage (Vdsl); (S380) Has the number of performing E/W cycling process reached a target number ? |
