An enhanced erase mechanism during channel Fowler-Nordheim tunneling in flash EPROM memory devices

An enhanced erase behaviour observed during the channel Fowler-Nordheim (FN) tunneling erase operation was examined in details. This enhanced erase occurs when a high p-well voltage is used, with the source and drain junctions of the cell left floating, during the erase operation. Our investigation indicates that the floating source and drain take on a high junction voltage during the p-well voltage transient. This causes transient band-to-band tunneling, and in some cases, junction avalanche breakdown, to occur in the source and drain junctions. As a result, hot-hole injection into the floating gate takes place to create this enhanced erase phenomenon.