US Patent 10454025 Phase change memory with gradual resistance change

A phase change memory cell is provided that includes a phase change material-containing structure sandwiched between first and second electrodes. The phase change material-containing structure has a resistance that changes gradually, and thus may be used in analog or neuromorphic computing. The phase change material-containing structure may contain a plurality of phase change material pillars, wherein each phase change material pillar has a different phase change material composition. Alternatively, the phase change material-containing structure may contain a doped phase change material layer in which a dopant concentration decreases laterally inward from an outermost surface thereof.