Research On Chemical And Mechanical Synergistic Polishing Of SiC Material

As the rapid and continuous development of national industries,especially the automobile,electronic information,aerospace and military filed.Si C material is deeply and widely used.However,it is quite hard,fragile and difficult to polish.Traditional polishing method shows low polishing efficiency,high cost and poor polishing roughness.Aimed at SiC material,CMP technology can promote polishing efficiency,shorten the production cycle and cut the cost.What's more,CMP can get better polishing surface quality.CMP technology consists of ehemism and mechanism.Therefore,during polishing process,should consider not only chemical and mechanical separately,but also the synergistic effect of them.The main research contents in this dissertation are as follows:(1)Principle of chemical modification.Using hydrogen peroxide to modify the surface of SiC workpiece.Changing the material properties to promote mechanical removal rate.Based on the principle of surface diffusion and the oxidation model to establish the chemical reaction rate model.Getting the changing regulations and affecting factors of chemical reaction rate.Through the experiment to obtain the hardness and depth of modified layer.(2)Principle of mechanical removal.traditional Preston model considers effects of pressure and velocity,it shows no effects of abrasive particles,polishing pad and some other factors.Aimed at this problem,based on the properties of polishing pad,considering the removal depth model of single abrasive particle and active particles numbers.Combined with velocity,establish removal model of single particle.Then,whole material removal explained as a superposition of single particle removal.getting removal depth and profile of whole active abrasive particles act.then integrate this profile will get the material removal rate.This model can predict the influence of pressure and velocity on the material removal.also indicated the effects of abrasive particle,polishing pad.At the same time,considered the particle distortion and concentration makes the model reasonable.(3)It is important to verify the accuracy of single abrasive paticle removal.prefer using simulation to verify the accuracy rather than doing experiment because of the limitation of conditions.ABAQUS is choosen.Analyse the residual stress remained on surface after polishing can suggest the influence of polishing condition on the property of SiC.Analyse the PEEQ profile can suggest the influence of polishing condition on the material removal.analyse the section depth can suggest the influence of polishing condition on the surface roughness.Doing the experiment to verify the rules of surface roughness,and getting good consistency with the results of simulation.(4)Through experiment to obtain the effect of chemical and mechanical synergistic polishing.observed that removal rate on the modified layer obviously higher than SiC layer.And then analysing the influence of polishing slurry on the material removal rate,getting the optimized polishing condition.