Sb-rich Si–Sb–Te Phase-Change Material for Phase-Change Random Access Memory Applications

An Sb-rich (48 at.%) Si-Sb-Te phase-change material with moderate Si content (24 at.%) is proposed for phase-change random access memory (PCRAM) applications. The real time amorphous to crystalline transformation was studied by in situ transmission electron microscopy observations and in situ resistance measurements. The results of time-dependent resistance measurements show that the Si₂₄Sb₄₈Te₂₈ phase-change material has data retention of 10 years at about 382 K, suggesting a more stable amorphous state than the usual Ge₂Sb₂Te₅ (GST) phase-change material. The reversible set-reset ability of the PCRAM cell based on the Si₂₄Sb₄₈Te₂₈ phase-change material is much better than that of the device employing GST. The programming cycles can reach 2.2 × 10⁴ under a set pulse of 1.5 V/1000 ns with a 30-ns falling edge and a reset pulse of 3.5 V/400 ns, whereas the resistance contrast retains a value of as large as two orders of magnitude.