Storage devices and methods of operating storage devices

Abstract

A storage device, including a nonvolatile memory device and a storage controller configured to control the nonvolatile memory device. The nonvolatile memory device includes a memory cell array including a plurality of word-lines stacked on a substrate, a plurality of memory cells provided in a plurality of channel holes, and a word-line cut region dividing the plurality of word-lines into a plurality of memory blocks. The storage controller groups a plurality of target memory cells into outer cells and inner cells. The storage controller includes an error correction code (ECC) decoder configured to perform an ECC decoding operation by obtaining outer cell bits and inner cell bits during a read operation on the plurality of target memory cells, and applying different log likelihood ratio (LLR) values to the outer cell bits and the inner cell bits.