Patent ID: 7477547

Claim:
A method of operating a reprogrammable non-volatile memory system having at least one group of charge storage memory cells connected in strings that individually contain a plurality of series connected memory cells between ends of the strings, comprising: identify those memory cells within the group adjacent ends of the strings to have a higher degree of vulnerability to being disturbed by a data read than other memory cells of the group not adjacent the ends of the strings, recognize when at least some of the memory cells of the group that are not adjacent the ends of the strings have been accessed and the data stored therein read in response to a command, subsequently scrub read data from at least some of the memory cells adjacent the ends of the strings of memory cells, determine a level of quality of the scrub read data and whether it is adequate, and if the level of quality of the scrub read data is determined not to be adequate, refresh the data stored in at least some of the memory cells of the group that are adjacent ends of the strings.