The phase-change memory with a separate-heater layer design for the multilevel storage device/ Che Norzakiman Che Ahmad

A phase-change memory structure with a separate heater layer was proposed to enable crystallization process for multilevel storage. This is to overcome the problem faced by the conventional design which is the difficulties to control the crystallization process in order to achieve the multilevel storage. A finite element analysis was conducted to investigate the possibility of multilevel storage using COMSOL 4.4 Multiphysics software. A 100ns SET pulses with an increasing amplitude from 0.1V to 0.7V were applied for heating the memory layer, which is Ge2Se2T5 (GST). The transition from the amorphous to the crystalline phases induced by heating the material above its crystallization temperature (450K-900K) and switching back to the amorphous state is realized by melting and quenching the material. The result is the proposed design shows more data to be stored in order to achieve the multilevel storage than the conventional design of phase-change memory with a 50nm thickness of memory layer (GST) and the 500nm width of the structure itself.