US Patent 7724560 Nonvolatile memory device having twin memory cells

A nonvolatile memory device includes multiple first bit lines extending in a first direction, multiple word lines formed on the first bit lines and extending in a second direction different from the first direction, and multiple second bit lines, formed on the word lines and extending in the first direction. The nonvoliative memory device also includes multiple twin memory cells, each of which includes a first memory cell coupled between a first bit line and a word line and a second memory cell coupled between the word line and a second bit line. The first and second memory cells store different data.