Research On Control Technology Of Magnetorheological Corrective Polishing For Semiconductor Substrate Materials

Semiconductor substrate materials are widely used in energy,information,transportation,national defense and other fields.It is one of the foundations that support the development of strategic emerging industries.One of the key technologies is the ultra-smooth polishing technology of semiconductor substrate materials.Optical element processing technology can no longer meet the technical requirements.Magnetorheological polishing technology is a polishing method capable of achieving ultra-smoothness and no sub-surface damage,and the polishing process can reduce the pressure of the polishing head on the semiconductor substrate material and avoid deformation.This article mainly uses the laboratorial self-developed ring belt magnetorheological polishing machine to study the precision polishing control system of semiconductor substrate materials.The main tasks completed are as follows:1)First,an overall control system design.The principle of the ring belt magnetorheological polishing and design a polishing plan is analyzed.The mathematical model for removing the ring belt magnetorheological polishing material is established.After that,the amount of parameters that need to be controlled is obtained,and the overall control system plan is carried out.Take PLC as the core controller to control the software and hardware system of the entire equipment,including servo control system,polishing pressure control system,grinding head control system,polishing liquid circulation control system and monitoring and alarm system,the touch screen realizes the man-machine exchange function,and researches and analyzes the running path of repairing and polishing.2)Hardware control system of polishing machine.Design the servo hardware system and circuit of the endless belt magnetorheological polishing machine to complete the reset system of the equipment,and analyze the operation accuracy of the equipment.Design precision measurement and control system,polishing head control system and polishing liquid circulation control system for polishing pressure to achieve precise control of polishing parameters.Based on the analysis of the hardware system,the electrical control system of the equipment is summarized,and the hardware preparation for the semiconductor substrate material precision polishing is completed.3)Polishing machine software design and control system testing.Write software programs,including hardware system,process system and monitoring and alarm system,to make the touch screen complete the man-machine exchange function;design the control process of the polishing machine to realize the manual polishing and automatic polishing of the equipment as the completion of the software for precision polishing semiconductor substrate materials,carryout software and hardware test analysis of the overall control system.4)Remove process experiment.The polishing material removal process experimental results show that the theoretical calculation value is in good agreement with the experimental measurement value,which confirms that the mathematical model of the ring belt magnetorheological removal is accurated.The single crystal sapphire substrate was polished,with the tested surface roughness being 0.803 nm,which was verified that the control system of the device meets the process requirements.