Identification and operation of sub-prime blocks in nonvolatile memory

摘要

In a block-erasable nonvolatile memory array, blocks are categorized as bad blocks, prime blocks, and sub-prime blocks. Sub-prime blocks are identified from their proximity to bad blocks or from testing. Sub-prime blocks are configured for limited operation (e.g. only storing non-critical data, or data copied elsewhere, or using some additional or enhanced redundancy scheme).

主权项

1. A method of operating blocks of a memory array comprising:
categorizing the blocks into a plurality of categories including prime blocks, sub-prime blocks, and bad blocks; wherein the categorizing includes identifying a bad block from test results obtained from the bad block, and subsequently identifying sub-prime blocks based on their proximity to the bad block; subsequently selecting individual blocks in different planes for parallel operation in metablocks such that each block in a metablock is selected from the same category; configuring metablocks formed from prime blocks as prime metablocks that are operated in a first manner; and configuring metablocks formed from sub-prime blocks as sub-prime metablocks that are operated in a second manner that is different from the first manner.