Micron Technology, Inc.
Reading Memory Cells Coarsely Programmed via Interleaved Two-Pass Data Programming Techniques

Abstract:

A memory system to store multiple bits of data in a memory cell. After receiving the data bits, a memory device coarsely programs a threshold voltage of the memory cell to a first level representative of a combination of values of the data bits according to a mapping between combinations of values of bits and threshold levels. The threshold levels are partitioned into a plurality of groups, each containing a subset of the threshold levels. XOR (or XNOR) is used to combine the data bits into bits of a group identification of a first group, among the plurality of groups, that contains the first level. The memory device reads, using the group identification, the data bits back from the first memory cell to finely program the threshold voltage of the memory cell to represent the data bits.