| 摘要 |
A double-bit non-volatile memory cell structure and a method of programming the memory cell. The memory cell includes a pair of stacked gates above a substrate, a doped region in the substrate between the stacked gate pair and a source/drain region in the substrate on each side of the stacked gate pair. The source/drain regions and the doped region are doped identically. To write data into the memory cell, the channel underneath both stacked gates is opened simultaneously. Data is written into the desired floating gate by controlling current flow direction. To read data from a first floating gate of the memory cell, a read bias voltage is applied to the first control gate above the first floating gate. In the meantime, a transfer voltage is applied to the second control gate. The presence or the absence of a conductive channel between the source/drain regions indicates whether data has been written into the first floating gate or not. The read bias voltage is greater than the threshold voltage of the first/the second floating gate in the erased state but smaller than the threshold voltage in the written state. The transfer voltage is greater than the threshold voltage in the written state.
|
