Patent ID: 7057940

Claim:
A method of operating a flash memory cell array, said flash memory cell array comprising a serial connection of a plurality of flash memory cells, a drain region and a source region in a substrate and positioned on the one side and the other side out of said control gates and said stacked gate structures respectively, each of said flash memory cell including a stacked gate structure having a select gate, a control gate positioned and connected on the one side of said stacked gate structure, a floating gate positioned between said control gate and said substrate, wherein said stacked gate structure of said plurality of flash memory cell structures juxtaposing alternatively with a stack structure having said control gate and said floating gate, said method comprising: before programming said flash memory cell array, applying a first voltage, a second voltage, and a third voltage to said source region, said select gates, and said control gates respectively and applying substantially 0 voltage to said drain region and said substrate, in order to turn on the channels of said flash memory cells; during programming said flash memory cell array, applying said first voltage, a fourth voltage, said second voltage, a fifth voltage, said third voltage, and substantially 0 voltage to said source region, said select gates of selected said flash memory cells, said select gates of non-selected said flash memory cells, said control gates of said selected flash memory cells, said control gates of said non-selected flash memory cells, and said substrate respectively, to cause source-side injection in order to inject electrons into said selected flash memory cells to program said selected flash memory cells; during reading said flash memory cell array, applying substantially 0 voltage, a sixth voltage, a seventh voltage, and a eight voltage to said source region, said select gates, said control gates, said drain region respectively; and during erasing said flash memory cell array, applying substantially 0 voltage to said source region and said select gates arid said control gates, and applying a ninth voltage to said substrate, to cause Fowler-Nordhem tunneling in order to push electrons from said floating gates into said substrate to erase said flash memory cell array.