A Phase Change Memory Cell With Metal Nitride Liner as a Resistance Stabilizer to Reduce Read Current Noise for MLC Optimization

Relatively large noise of phase change material is one of the obstacles for realization of multilevel cell (MLC) using phase change memory (PCM) technology. We experimentally verify that the noise in PCM can be lowered as much as ~4 times by a novel PCM cell which utilizes metal nitride liner to provide an alternative conductive path to the amorphous region with large noise. Program-and-verify (PNV) simulation based on noise measurement data confirms that the small noise of a PCM cell with metal nitride liner improves the MLC performance either by reducing number of PNV iterations or bit-error rate.