Data recovery in a 3D memory device with a short circuit between word lines

摘要

Techniques for detecting word line layers which are shorted together due to a defect in a three-dimensional stack memory device, and for recovering data. The memory device comprises blocks of memory cells in which each block has a separate stack of word line layers but the word line layers at a common height in the different stacks are connected. A process to detect a short circuit occurs when an nth word line layer (WLn) in an ith block fails to successfully complete programming. A determination is made as to whether WLn is shorted to WLn−1 and/or WLn+1. If WLn is shorted to WLn+1 but not WLn−1 in the ith block, a recovery read process is performed to read the data which has been programmed into the memory cells of WLn of the previously-programmed blocks. The recovery read process uses upshifted control gate read voltages due to the short circuit.

主权项

1. A memory device, comprising:
a first non-failure block, the first non-failure block comprises memory cells arranged in a plurality of word line layers; a failure block, the failure block comprises memory cells arranged in a plurality of word line layers which correspond to the plurality of word line layers of the first non-failure block; an interconnect structure which connects each word line layer of the plurality of word line layers of the first non-failure block to a corresponding word line layer of the plurality of word line layers of the failure block; and a control circuit, the control circuit is configured to:
program data into memory cells of the first non-failure block;make a detection of a failure in an attempt to program data into memory cells of a particular word line layer in the failure block;in response to the detection of the failure, make a determination that the particular word line layer in the failure block is shorted to a first higher word line layer above the particular word line layer but not to a first lower word line layer below the particular word line layer; andin response to the determination, read data from memory cells of a particular word line layer in the first non-failure block which corresponds to the particular word line layer of the failure block.