Experimental Study On Magnetorheological Chemical Finishing Process Of Large Polishing Tool For SiC Substrates

Semiconductor materials are playing an increasingly important role with the development of IC industry at a rapid rate.Furthermore,the demand for semiconductor materials,as well as the requirements of semiconductor materials processing technology are increasing.Single crystal silicon carbide can meet the changing use requirements,which as the representative of the third generation of semiconductor materials due to the large band gap width,high electron saturation drift rate,high breakdown field strength,high thermal conductivity and other advantages.However,the traditional processing method is difficult to achieve the surface of super-smooth surface with high-efficiency,high-precision and low damage polishing because that single crystal silicon carbide has the characteristics of high hardness,high brittleness and so on.Magnetorheological chemical finishing is a cutting-edge polishing method that can achieve ultra-smooth and low damaging processing.It employs a magnetorheological polishing process in conjunction with a high-performance chemical polishing fluid to achieve a high efficiency ultra-smooth surface removal effect.Therefore,the magnetorheological chemical finishing technology of large polishing tool for silicon carbide substrates was proposed in this paper.The following were the main research contents and findings:(1)The magnetorheological chemical finishing process of large polishing tool was proposed and used to polish silicon carbide substrates.A new polishing fluid recipe has been proposed to improve the polishing efficiency.The principle of magnetorheological finishing and the special material of silicon carbide substrates were investigated.The effects of various abrasive types,abrasive particle size,abrasive concentration,magnetic particle concentration,oxidant concentration,value of pH,and dispersant on the magnetorheological chemical finishing effect of single crystal silicon carbide were investigated using a single factor experiment,and the polishing fluid composition was optimized.(2)The impact of process parameters on polishing effect was investigated,and the orthogonal experimental process parameters were changed using a comprehensive weighting technique.The impacts of workpiece speed,polishing disc speed,working gap,and excitation gap on the polishing effect of silicon carbide substrate were investigated using orthogonal experiments.By employing material removal rate and surface roughness as indexes,the synthetic weighting approach was applied to optimize the process parameters.(3)The magnetorheological chemical finishing process of large polishing tool for silicon carbide substrate was evaluated experimentally.It is proven that the procedure provides an efficiency and nano-level ultra-smooth surface polishing effect by comparing testing results before and after optimization,and different processes.The studies demonstrate that after polishing the Cface has a surface roughness value of Ra 0.32 nm while the Si-face has a surface roughness value of Ra 0.34 nm.