Reactive Ion Etching Technology And Mechanism Of New Phase Change Materials Chromium Doped Antimony Telluride

Chromium-doped antimony tellurium(Cr-SbTe)is a new type of phase change memory material.Compared with traditional germanium(GST)phase change materials,it has the advantages of high stability,low power consumption and fast operation speed.One of the important processes required to fabricate a phase change memory device with a confinement structure is etching,and the etching process for this new material is barely reported.Therefore,this paper mainly explores and studies the process parameters and etching mechanism of reactive ion etching of Cr-SbTe materials,which has certain scientific research and practical application significance.In this paper,the effect of power on the film quality during the magnetron sputtering growth of Cr-SbTe was studied.The RF sputtering power of 30W was optimized.Then,the research on the etching process of Cr-SbTe material is mainly the composition of the etching gas and the flow ratio,the RF power,the working pressure and other parameters on the etching rate,the selectivity and the surface roughness of the sample after etching.It is found that the concentration of fluorine-based gas in the mixed gas has a great influence on the etching rate.The surface roughness after etching with CF₄/Ar gas is generally larger than that of CHF₃/O₂.As the RF power increases,the etch rate of the sample increases first and then decreases.As the chamber pressure increases,the etch rate increases first and then decreases,and the surface roughness of the sample decreases first and then increases.After the above etching parameters were combined,a mixed gas of CHF₃/O₂=40:10 was obtained.Under the150W RF power and the chamber pressure of 15m Torr,the etching rate of the reactive ion etching Cr-SbTe sample was 108.1nm/min,the surface root mean square(RMS)roughness of the sample after etching is 0.447 nm,the selectivity of Cr-SbTe to the photoresist is 0.65,and the selectivity to Ti N is 6.54.Based on the above process parameters,the pattern transfer quality of Cr-SbTe,the steepness of sidewalls after etching,the chemical reaction mechanism during etching and the phase transition properties of materials before and after etching were studied.The sidewall straightness is related to the concentration of the fluorine-based gas in the mixed gas,and the sidewall straightness is higher when the fluorine-based gas concentration is lower.After comparing the XPS spectra of the sample surface before and after etching,it is found that Cr-SbTe films are easier to etch Cr and Te elements,but they are easy to produce fluorinated products after etching,while Sb elements The amount of fluorinated product produced after etching is small.The etching process has little effect on the phase change properties of the material.This paper provides a sufficient theoretical basis and practical basis for the preparation of Cr-SbTe-based phase change memory devices using etching technology.