The Research On Ultrasonic Vibration Assisted Photocatalytic Polishing Of Silicon Carbide

As a third-generation semiconductor material,single crystal silicon carbide has excellent physical and chemical properties.It has important applications in many fields at present,and the market demand is large.It is a key development industry in my country.Silicon carbide crystal needs to undergo a series of treatments to obtain a smooth and damage-free surface before it can be used to manufacture power devices.The polishing treatment of silicon carbide accounts for a high proportion in the entire processing process of silicon carbide.Single crystal silicon carbide has high hardness and is difficult to process.Traditional processing methods have problems such as low efficiency and abrasive agglomeration.In this paper,an ultrasonic vibration-assisted photocatalytic polishing method was proposed.（1）In order to quickly remove wire-cut traces,Si C wafers need to be pretreated before polishing.The single-crystal silicon carbide wafers were subjected to non-ultrasonic vibration-assisted grinding and ultrasonic vibration-assisted grinding experiments to study the effects of different process parameters on the material removal rate.By comparing the experimental results of non-ultrasonic vibration-assisted grinding and ultrasonic-assisted grinding,it is found that ultrasonic vibration can improve the material removal rate of grinding.By measuring the surface roughness during the grinding process,the optimal time for ultrasonic vibration-assisted grinding was determined.（2）The polishing of silicon carbide wafer was studied.The chemical mechanical polishing device was improved,and experiments of unassisted chemical mechanical polishing,ultrasonic vibration-assisted chemical mechanical polishing and ultrasonic vibration-assisted photocatalytic polishing of silicon carbide wafers were carried out.After the test,it was found that better test results can be obtained after setting the rotation speed of the polishing disc to60r/min,applying a pressure of 0.025MPa,adding 5wt%Si O₂ to the polishing liquid,and polishing with a polyurethane polishing pad.Ultrasonic vibration and photocatalysis improved the polishing effect.Ultrasonic vibration-assisted photocatalytic polishing under the above parameters obtained a surface of Ra 0.609 nm,and the material removal rate of polishing was1.003μm/h.（3）The mechanism of polishing scratches and material removal was analyzed.The common scratch damage on the polished surface was counted,and the reason and distribution of the scratch damage on the surface were analyzed combined with the structure of silicon carbide.The material removal process of silicon carbide was explained,and the effects of ultrasonic vibration and photocatalysis in the polishing process were analyzed.