| 摘要 |
A nonvolatile memory device having a predetermined threshold voltage is disclosed. In the nonvolatile memory device comprising a gate electrode including a control gate, a floating gate and a gate insulating layer, a source region and a drain region, a threshold voltage of an initial state applied to a word line such that the floating gate is electrically neutral is set to the mean value between the threshold voltage of a programmed state and the threshold voltage of an erased state. Thus, the amount of negative charges passing through a tunnel oxide layer during a program operation is the same as the amount of positive charges passing through the tunnel oxide layer during an erase operation, and an electric field formed on the tunnel oxide layer is minimized. Thus, the generation of electron traps in the tunnel oxide layer is reduced even though the program or erase operations are repeated, to thereby suppress the loss of the charges stored in the floating gate. As a result, the reliability of the device can be enhanced.
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