US Patent 7859885 Phase changing memory device

A phase change memory device includes a substrate, a plurality of cell arrays stacked above the substrate and each including a matrix layout of a plurality of memory cells, each the memory cell storing therein as data a resistance value determinable by a phase change, a write circuit configured to write a pair cell constituted by two neighboring memory cells within the plurality of cell arrays in such a manner as to write one of the pair cell into a high resistance value state and write the other into a low resistance value state, and a read circuit configured to read complementary resistance value states of the pair cell as a one bit of data.