Preparation Of Cr-Doped SbTe Phase Change Material And Investigation On Its Memory Cell

Phase change materials are the core issue in the research of phase change memory.At present,the most widely studied phase change layer material system is SbTe,but its application is limited because of the amorphous thermal stability of SbTe.It has been proved that doping is an efficient method for modification.Therefore,the improvement of amorphous thermal stability and other properties of SbTe materials by doping Cr in this article is necessary for the study of new phase change materials.Under this background,this paper is of important research significance.The research content of this article mainly includes the following two parts:1.Preparation and optimization of Cr-SbTe phase change film:Cr-SbTe phase change film was prepared by magnetron sputtering method,and its sputtering power,working pressure,and Cr element doping concentration were optimized;SEM,AFM,XPS,XRD,B1500 semiconductor parameter analyzer and other characterization methods were used to characterize the film growth rate,surface morphology,film composition,film crystalline,amorphous resistance,crystal orientation and phase transition temperature.Besides,the formation of bonds was analyzed.The growth conditions were optimized:the sputtering power was 50 W,the working pressure was0.2 Pa,and the Cr doping concentration was 7.4 at.%.XRD and analysis show that Cr doping can effectively reduce the grain size,and the refined grains contribute to the reduction of film surface roughness and phase change volume change;XPS analysis shows that Cr is easy to form bond with Sb and Te,which effectively prevents the oxidation of the phase change material and is of great significance for improving the amorphous thermal stability of the phase change material.2.Based on the construction of Cr-SbTe phase change unit and the test of its electrical performance.Al/W/Cr_xSbTe/Pt(X=0,3.59,7.4,10.73 at%)phase change unit and Al(Pt/Ti)/W/Cr_7.4SbTe/Pt structured phase change unit were constructed.DC scan test,window test,phase change device consistency statistics and switching ratio statistics were performed.Tests show that with the increase of the Cr doping concentration,the DC scan threshold current of the prepared phase change unit and the resistance of the amorphous resistor increases,which is related to the improvement of the thermal stability of the doped material.The pulse test shows that the device has the potential for rapid phase change.When the Cr doping concentration is 7.4,the prepared phase change unit have a switching ratio of up to 10⁵orders and an amorphous resistance of 10⁷?.The electrode material with low thermal conductivity helps significantly reduce power consumption of phase change memory unit.However materials with poor ductility(Pt,Ti)as the bottom electrode material of the phase change unit are prone to device failure due to the mismatch with heating electrode.The Cr-SbTe phase change material studied in this paper is expected to be useful for the preparation of fast phase change memories,which provides a guiding significance for the enrichment of phase change material systems.