Research On TiTe₂ Doped Sb₂Te₃ Phase Change Materials And Memory Devices

Information lays the foundation for the construction of human material civilization.As a medium for storing information,memory plays an increasingly important role in life.As the top of them,phase change memory has the advantages of non-volatility,fast erasing and writing speed,and long cycling endurance,and has huge potential in the field of storage.The phase change material with nucleation-dominant crystallization has a slower SET speed,while Sb₂Te₃,as the growth-dominant crystallization phase change material,has a faster SET speed,but the crystallization temperature is low and the amorphous stability is poor.In this paper,a stable binary compound TiTe₂-doped Sb₂Te₃ phase-change memory cell is proposed,which can improve the amorphous stability of Sb₂Te₃ without sacrificing its SET speed,and even further increase its SET speed.In this paper,TiTe₂-doped Sb₂Te₃phase change films were prepared by magnetron sputtering process,and the proportion of doped TiTe₂ was determined by energy dispersive spectroscopy.The film thickness,deposition rate and surface morphology was measured by atomic force microscope.Phase analysis was carried out by X-ray diffraction and grain size was observed by transmission electron microscope.The results show that Sb₂Te₃ and TiTe₂ are crystallized separately in TiTe₂-doped Sb₂Te₃ phase change film materials.Doping TiTe₂ can reduce the surface roughness and grain size of Sb₂Te₃.From the analysis of temperature characteristics,doping TiTe₂ can improve the crystallization temperature and ten-year data retention temperature of Sb₂Te₃ phase change film materials.In this paper,TiTe₂-doped Sb₂Te₃phase change memory cells with pinhole structure were fabricated by magnetron sputtering,electron beam lithography,ultraviolet lithography and other processes.The two groups with large difference in doping ratio were selected for comparison with pure Sb₂Te₃ phase change memory cell.The I-V characteristics,RESET power consumption,SET speed and resistance drift coefficient of the phase-change memory cells were tested respectively.The results show that doping TiTe₂ can effectively improve the amorphous stability of Sb₂Te₃ phase-change memory cell,further improve its SET speed,reduce its power consumption,and suppress resistance drift.In order to further explore the reasons for the improved performance of TiTe₂-doped Sb₂Te₃ phase-change memory cells,thermal simulations were carried out in this paper to clarify the mechanisms of low power consumption.