New operation mode for stacked-gate flash memory cell

A new operational mode is proposed that lowers the threshold voltage of a stacked-gate flash memory cell. The mode features the set-up of the word-line voltage and bit-line voltage. An AC signal is applied to a word-line while a bit-line is kept floating after it is charged. The signal is applied to lower the threshold voltage of the cell and to test it. A SPICE simulation of this operation has revealed that the converged voltage of floating gate has negligible dependency on the initial voltage and the tunnel oxide thickness and that the cell threshold voltage is controllable through the world-line voltage. This operation mode is easily applicable to a conventional flash memory. Furthermore, it may allow the use of flash cells in analog applications or in multi-level memory cells.<
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