C-Sb Materials as Candidate for Phase-Change Memory

We studied crystallization behaviors of amorphous C-Sb films to evaluate their applicability in phase-change memory. C-Sb thin-films with 92 to 50 at% Sb were deposited by co-sputtering from elemental targets. In-situ electrical resistance-temperature measurement, differential thermal analysis, and grazing-incident X-ray diffraction were applied in this work. Kinetics of crystallization was explored using Kissinger's non-isothermal method and Arrhenius' isothermal method, respectively. As-deposited C-Sb films are amorphous whose electrical resistance decreases as increasing temperature with a 4 to 3 orders-of-magnitude drop at the crystallization temperature. The crystallization temperature increases from 263 to 275°C as Sb content decreases from 90 to 83 at%. The melting temperature remains almost unchanged, 624°C, denoting the melting of Sb. The activation energy of crystallization increases from 3.37 eV (90 at% Sb) to 3.88 eV (83% Sb). Structure of C-Sb films after full crystallization belongs to R3̅m̅ Sb phase. The temperature corresponding to 10-year data-retention of 87 at% Sb films is 168°C. Electrical switching characterized using a memory-device made of 87 at% Sb film works smoothly at voltages with 50 ns pulse-width, set at 1.1 V and reset at 2.8 V. Binary C-Sb materials, being compatible with CMOS pro cessing, are predicted to be promising candidates for use as phase-change memory.