Selection of Data for Redundancy Calculation in Three Dimensional Nonvolatile Memory

摘要

Portions of data stored in a three dimensional memory array are selected based on their locations for calculation of redundancy data. Locations are selected so that no two portions in a set of portions for a given calculation are likely to become uncorrectable at the same time. Selected portions may be separated by at least one word line and separated by at least one string in a block.

主权项

1. A method of operating a three dimensional nonvolatile NAND memory in which an individual block contains a plurality of NAND strings connected to each bit line, and in which word lines of different strings along a bit line are connected together, comprising:
receiving portions of data to be stored in the three dimensional nonvolatile NAND memory array; assigning the portions of data to physical locations for storage in the three dimensional nonvolatile NAND memory array, an individual portion assigned to a location defined by: (i) a block, (ii) a plurality of bit lines that serve the block, (iii) a set of strings selected from a plurality of sets of strings connected to the plurality of bit lines in the block, and (iv) a word line coupled to the set of strings; selecting a set of two or more portions of data for calculation of redundancy data, the two or more portions of data selected according their assigned physical locations so that none of the two or more portions of data are assigned to connected word lines of different sets of strings of an individual block; and calculating redundancy data for the set of two or more portions of data, the redundancy data calculated from the set of two or more portions of data so that any individual portion of the two or more portions can be calculated from the redundancy data and portions of the set of data other than the individual portion.