DATA STORAGE DEVICE HAVING SUPERIOR DATA RETENTION CHARACTERISTIC AND METHOD

A data storage device such as a flash memory device and the like, and a method and device for storing data in a data memory means. The data storage device comprises: a plurality of data memory means such as floating gate MOS transistors; data charge injecting means which selectively injects electric charges into said floating gate of each of the data memory means to write data to the data memory means. The data storage device also comprises a trap dissolving means which injects additional electric charges into the floating gates of at least a part of the plurality of data memory means to compensate for deterioration of a threshold voltage of each of the data memory means caused by the movement of electric charges from the floating gate to trap sites in the tunnel oxide film a predetermined time, after the data charge injecting means injects electric charges into the floating gates to write the data to the data memory means.