Patent ID: 7463526
Filing Date: 2008-12-09
Classification: G11C

Abstract:
1. A programming method for a flash memory device having a plurality of memory cells storing multi-bit data indicating one of a plurality of states, the programming method comprising: programming selected memory cells with multi-bit data to have one of the plurality of states using a first programming operation; following programming of the selected memory cells with multi-bit data using the first programming operation, detecting programmed memory cells arranged within a predetermined region of a threshold voltage distribution, the region corresponding to at least two of the plurality of states, wherein predetermined regions of the respective at least two of the plurality of states are selected by one of a first verify voltage and a read voltage and a second verify voltage, the first verify voltage being lower than the second verify voltage and higher than the read voltage; and following detection of the programmed memory cells and using a second programming operation, simultaneously programming detected memory cells of the at least two of the plurality of states to have a threshold voltage equivalent to or higher than the second verify voltage corresponding to each of the plurality of states.