Interfacial Engineering Regulated Superlattice Phase Change Materials And Its Mechanism Of Low Power Consumption And High Speed Phase Transition

Phase change random access memory(PCM)is regarded as one of the most promising novel non-volatile memory technology for some reason about its faster threshold transition speed,lower power consumption,higher storage density,non-volatile and compatibility with CMOS process.In recent years,with the advent of 3D XPoint technology,a giant leap have been filled up in the research of PCM,and related products have also been applied to mobile phones,hard disks,memory,etc.However,the development of PCM is severely limited by phase change materials.The PCM's technology based on the commonly used Ge-Sb-Te system is severely affected by the reliability and life of devices due to the complex preparation process,serious segregation of material components in multiple cycles,and the difficulty in obtaining uniform element distribution at the nanoscale.In this paper,we proposed a research technology to control the properties of PCM by interface effect,expand the research method of PCM,and prepare corresponding devices based on this material to test the electrical properties,and verify the feasibility of its application in PCM.The research outputs of are as follows:1.Preparation of out-of-plane height(0 0 l)texture-oriented films.Mo/Sb₂Te₃(MST) superlattice phase transition films with out-of-plane(0 0 l)texture orientation were prepared by magnetron sputtering.The effects of deposition parameters such as temperature,sputtering pressure,and deposition sequence on crystal structure orientation of thin films were studied.2.Interfacial engineering regulates material properties.The effect of interface effect on the properties of phase change materials was investigated by inserting atomically thick transition metal Mo layers into Sb₂Te₃ intervals.X-ray photoelectron spectroscopy(XPS)analysis shows that Mo and Te atomic combined to form Mo-Te bond in MST film material,and form a single atom Te layer at the interface of the heterojunction,which is conducive to the layered growth of Sb₂Te₃ crystal and obtained high-quality MST film.Meanwhile,the existence of Mo layer limits the longitudinal growth of Sb₂Te₃ grain to a large extent,plays a role in grain refinement, and avoids device failure due to large volume changes before and after grain transformation.3.Preparation and electrical properties of phase-change memory devices.Introduced the cell structure and fabrication process of PCM device based on MST superlattice phase change film and tested its electrical properties.Obtained with faster threshold transition speed,lower power consumption,higher storage density and endurance characteristics of PCM device more than 5×10~5.The mechanism of phase transformation was uncovered by analyzing the microstructure of the device cell after pulse operation.It is found that the MST-based PCM device has low resistance drift coefficient and all intermediate states can exist stably,which is anticipated to be applied in multilevel storage.