Error recovery storage along a memory string

摘要

Apparatus and methods store error recovery data in different dimensions of a memory array. For example, in one dimension, block error correction codes (ECC) are used, and in another dimension, supplemental error correction codes, such as convolutional codes, are used. By using separate dimensions, the likelihood that a defect affects both error recovery techniques is lessened, thereby increasing the probability that error recovery can be performed successfully. In one example, block error correction codes are used for data stored along rows, and this data is stored in one level of multiple-level cells of the array. Supplemental error correction codes are used for data stored along columns, such as along the cells of a string, and the supplemental error correction codes are stored in a different level than the error correction codes.

主权项

1. A method of storing error recovery data for a memory array having two or more levels, the method comprising:
storing data with a block error correction code using a first level of multiple-level cells and along a first dimension of the memory array; storing data with a supplemental error correction code using a second level of the multiple-level cells and along a second dimension of the memory array, wherein the second dimension is along a column of the memory array, wherein the supplemental error correction code is incrementally updateable; and computing a supplemental error correction code based on data stored in a first level of a previously-written row and current data to be stored.