Dual-cell soft programming for virtual-ground memory arrays

摘要

A technique for controlling the soft-program current in virtual-ground FLASH memory arrays is described. It is based on biasing the array bit-lines such that all current supplied to the array is used entirely towards the soft-programming of selected cells. The result is control of the soft-programming current and the programming rate of individual cell pairs. The benefit of soft-programming is then realized during the actual cell programming with the improved control of current and program rate. This is described with respect to an embodiment that uses source-side injection as the means for programming memory cells and with respect to a second embodiment based on a cell with dual floating gates.