Patent ID: 6301157
Filing Date: 2001-10-09
Classification: G06F,G11C

Abstract:
A method for testing memory cells in a multilevel memory device having a plurality of memory cells, comprising:reading the individual memory cells that constitute a memory device and comparing each one of said memory cells with at least one reference memory cell at a time to determine whether the threshold of said memory cells is lower than the threshold of said at least one reference memory cell;determining the number of said memory cells whose threshold is higher than the threshold of said at least one reference cell;said at least one reference memory cell being chosen with a gradually higher threshold;when said number of memory cells whose threshold is higher than a given reference threshold is found to be sufficiently lower than the number of redundancy memory cells provided in the memory device, assuming said given reference threshold as lower reference threshold for said memory device, determining a statistical distribution of the thresholds of said memory cells.