Study On Radio Frequency Ion Beam Etching Of ZnS Optical Element

With the development of optical technology and high precision requirements of optical elements,zinc sulfide material has been widely used in the infrared window,cowling and other aspects because of its good infrared characteristics.The surface roughness of zinc sulfide must meet the higher requirements.Ion beam polishing can produce high-precision optical elements.It has high application value to research ion beam polishing of zinc sulfide optical elements.In this paper,ion beam etching technology is used to etch and polish zinc sulfide wafers.SRIM software is used to simulate the impact of incident ions on the surface of zinc sulfide yield on the surface.The effect of different process parameters on the surface roughness of zinc sulfide is studied by direct etching of zinc sulfide with ion beam etching machine.In addition,the microstructure of zinc sulfide wafer is analyzed by XRD and XPS.The planarization layer is prepared by coating,and the zinc sulfide is polished by ion beam deposition.The major work and conclusions are as follows:(1)Ar+incident zinc sulfide surface is simulated by SRIM software.The distribution and range statistics of simulated incident ions on the surface of zinc sulfide,etc.(2)The effects of ion beam incidence energy,ion beam incidence Angle,ion beam flow,etching time and rotation velocity on the surface roughness of zinc sulfide are studied.The best process parameters are:ion beam incident energy is 450eV,incident Angle is 45 degrees,ion beam current is 35mA,ion beam etching time is 1h and rotation speed is 60 r/min.(3)According to XRD analysis,the zinc sulfide used is cubic sphalerite structure.XPS is used to analyze the zinc sulfide wafer before and after Ar~+etching.The analysis show that Ar~+etching does not change the valence state of zinc sulfide wafer.The element Zn is+2 valence and S is-2 valence.(4)Ion beam deposition correction polishing zinc sulfide.The planarization layer is prepared by electron beam thermal evaporation.The influence of zinc sulfide films with different deposition thicknesses on the surface roughness of zinc sulfide substrate is investigated,and the surface roughness of zinc sulfide wafer is reduced from 1.94nm to 1.48nm by ion beam etching.