Research On Novel SbTe-based Phase Change Films And Storage Devices

Phase Change Random Access Memory(PCRAM)has the advantages of high integration,fast storage and reading speed,and compatibility with CMOS technology,and has become one of the most recognized new non-volatile memories with the most potential.PCRAM has replaced some FLASH memory chips to achieve applications,but it still needs to continue to develop if it wants to replace DRAM.PCRAM based on traditional Ge₂Sb₂Te₅(GST)as a storage medium cannot meet higher development requirements in terms of retention,operating speed,and power consumption.Compared with GST,Sb-Te binary materials have attracted the attention of researchers in recent years.Among Sb-Te system materials,Sb₂Te and Sb₂Te₃materials have been studied the most.This paper proposes and studies several new phase change storage materials based on Sb₂Te and Sb₂Te₃.Phase change films are prepared by magnetron sputtering,and storage devices based on new phase change materials are prepared by semiconductor technology.The material characteristics and devices are the innovative results of performance research are as follows:1.High-speed,low-power Al Sc-Sb₂Te new phase change materials and devices.A systematic study on Al Sc-doped Al Sc-Sb₂Te materials has been carried out.After doping with Al Sc alloy with an aluminum-scandium atomic ratio of 1:1,the properties of Sb₂Te are enhanced,including thermal stability,density change and phase transition speed.Through the doping of Al Sc alloy,the easy oxidation characteristic of pure Sc doping is avoided,and the thermal stability is also improved,the density change is reduced,and the phase transition speed is increased.Al Sc-Sb₂Te has a better 10-year data retention temperature(146°C)and a higher crystallization temperature(221°C),which reflects the excellent amorphous thermal stability of Al Sc-Sb₂Te.The X-ray reflection results show that the density change(2.6%)of the Al Sc-Sb₂Te material is much smaller than that of the traditional GST(6.5%).In addition,Al Sc-Sb₂Te-based devices have extremely low power consumption of 6.78×10^-12J,the fastest phase transition speed is 6 ns,the number of cycle operations is 1.5×10⁴,and the resistance drift of the Al Sc-Sb₂Te device is small.Therefore,Al Sc-Sb₂Te is a high-speed and low-power phase change material with application potential.2.Research on Al Sc-Sb₂Te₃new phase change materials and devices.The crystallization temperature of the traditional Sb₂Te₃matrix material is relatively low,and it can crystallize spontaneously at room temperature.Proposed and prepared Al Sc-Sb₂Te₃new phase change materials doped with Al Sc-Sb₂Te₃,and prepared memory devices based on Al Sc-Sb₂Te₃materials.The experimental results show that with the increase of Al Sc alloy doping content,the high and low resistance of Al Sc-Sb₂Te₃thin film materials increase significantly,and the ten-year data retention temperature of the material is increased to 133.8?.The Al Sc-Sb₂Te₃material has better thermal stability than the material before doping.The X-ray diffraction results indicate that the incorporation of Al Sc alloy inhibits the crystallization of Sb₂Te₃,improves thermal stability,and refines the grain size.Devices based on Al Sc-Sb₂Te₃can achieve reversible phase transitions with a pulse width of 10 ns.At this time,the resistance ratio is about 10³,and the phase change operation cycle reaches 2×10⁴times.The excellent performance of Al Sc-Sb₂Te₃film makes it a potential PCRAM application material.3.Propose a new phase change material doped with non-metal element boron(B)B-Sb₂Te₃(BST).In the film doped with B element,with the increase of the proportion of B element,the high and low resistance of the film material increases at the same time the high and low resistance ratio also tends to increase;the doping of B element inhibits the crystallization of Sb₂Te₃and improves the thermal stability;When the pulse width is 6 ns,the resistance ratio of the two is more than two orders of magnitude,and the power consumption is 2.53×10^-12J.The experimental results show that the B-doped Sb₂Te₃material is a potential new PCRAM material.