Data Recovery on Cluster Failures and ECC Enhancements with Code Word Interleaving

摘要

Techniques are presented for dealing with errors that arise from cluster fails, where a number of memory cells in the same area fail. An ECC code word can tolerate a given total amount of error while still being able to still be decoded, so that if error due to clusters can be identified and removed or lessened, it may be possible to still decode the word not otherwise decodable. After identifying possible error bit cluster locations, one or more bits in the cluster locations are flipped to see if the data content of the code word can be extracted. For embodiments using LDPC ECC code, uncertainty can be added for the bits of a suspected cluster location. To reduce the effects of cluster failures, code words can be interleaved within a page and the difference code words can have differing levels of ECC capability.

主权项

1. A method of writing data to a non-volatile memory system, the memory system including a memory circuit having an array of memory cells formed along bit lines and word lines and a controller circuit connected to the memory circuit and having ECC circuitry, the method comprising:
receiving a set of data at the controller circuit; forming the data into ECC code words, each ECC code word including a plurality of bits of data and one or more bits of error correction code associated with the data; and writing a first plurality of the ECC code words onto a first word line of the array, wherein the ECC code word are written in an interleaved manner wherein at least some of the ECC code words are not written into a contiguous set of memory cells along the first word line.