Patent ID: 9015561
Filing Date: 2015-04-21
Classification: G06F,G11C

Abstract:
1. A method of operating a three-dimensional nonvolatile memory that is monolithically formed in a plurality of physical levels of memory cells disposed above a substrate, memory cells in the plurality of physical levels connected in series to foim vertical NAND strings, comprising: categorizing the plurality of physical levels into at least a first category of physical levels and a second category of physical levels according to expected error rate, the first category of physical levels having a first expected error rate, the second category of physical levels having a second expected error rate that is less than the first expected error rate; performing a redundancy calculation for data in the first category of physical levels, across N blocks of the three-dimensional nonvolatile memory, to generate first redundant data; storing the first redundant data in a redundant block in the three-dimensional nonvolatile memory; performing a redundancy calculation for data in the second category of physical levels, across N+X blocks of the three-dimensional nonvolatile memory, to generate second redundant data; and storing the second redundant data in the redundant block.