Optimization Of Dynamic Cluster Magnetorheological Polishing Parameters Based On Improving The Processing Uniformity Of Optoelectronic Wafers

Magnetorheological polishing is an efficient and intelligent processing method that can be applied to the planarization and polishing process of optoelectronic wafers to obtain highquality surfaces with low roughness and no surface damage.In this thesis,aiming at the uniformity of the machining surface of the cluster magnetorheological planarization,a theoretical optimization method for improving the machining uniformity of the dynamic cluster magnetorheological polishing is proposed,and the process of improving the machining uniformity by combining the motion process parameters with the magnetic field distribution is studied.First of all,the roughness distribution law is searched through the light transmittance test of optical glass,and it is found that the reason for the uneven processing of the cluster magnetorheological planarization is mainly caused by the different positions of the workpiece surface passing through the strength of the magnetic field strength region and the length of the effective processing track.By increasing the rotational speed ratio,the roughness distribution law at the center position and edge position of the workpiece can be changed,and the uneven effect can be ameliorated.Secondly,a theoretical model of magnetic track intensity combining machining motion and magnetic field is established,and the material removal ability of effective motion track and magnetic field distribution on different positions of the photoelectric wafer is analyzed by numerical calculation.It is found that The speed ratio of workpiece and polishing disk has the greatest influence on machining uniformity.The length of the edge motion track can be increased by adjusting the rotation speed ratio of the workpiece and the polishing disk.Simultaneously,the eccentricity displacement can change the size of the magnetic field area on the track at different positions.When the motion track and the magnetic field intensity distribution match each other,the processing uniformity can be effectively improved.And the improvement effect on the roughness uniformity distribution is verified in the experiment.Thirdly,based on the requirements of large processing size and polishing uniformity,a new type of magnetorheological polishing device is designed.The public rotation motion scheme is selected.Through the combination of magnetic field simulation and numerical analysis,the magnetic field generating device of the new cluster magnetorheological polishing device is optimized and designed.The vertical and horizontal arrays and the staggered and different magnetic pole arrangements are selected,and the selection of cylindrical magnets is determined.Finally,the processing technology experiment is carried out on the newly developed magneto-rheological polishing device of space dynamic magnetic field of public rotation transformation.Effects of factors and combinations on roughness and material removal rates.Under the optimal speed ratio process,the initial surface roughness of Sa 4.5 nm can be reduced to Sa 0.92 nm after processing for 30 minutes,and the coefficient of variation of roughness is 0.22.homogenization processing.After prolonging the processing time to 120 min,the average roughness of the final surface are reduced to Sa 0.44 nm,and ultra-smooth planarization of silicon wafers is achieved.