Atomic-level engineering of phase change material for novel fast-switching and high-endurance PCM for storage class memory application

Storage class memory (SCM) does not need long data retention (since the data are refreshed regularly) but has very stringent requirements on read/write speed and cycling endurance. Even though phase change memory (PCM) is a leading candidate currently no phase change material can satisfy both speed and endurance requirements. This is because although GST-225 is a fast switching material it suffers large volume change when melting thus limited cycling endurance. Attempts to improve the endurance so far must sacrifice switching speed. This work explores new phase change material by atomic-level engineering the doping to GST. The resulting new phase-change material has demonstrated fast switching speed of 20 ns, long endurance of 1G cycles and low reset current of 150 μA in a 128 Mb test chip. Its data retention passed 20 years-55°C criteria with failure rate lower than 10ppm.