Study On The Controllable Synthesis And Mechanical Polishing Mechanism Of Micro/Nano Ceria

Cerium oxide,as a rare earth polishing material,has been widely used in the polishing of precision optical glass and ultra large scale integrated circuits.The micro/nano ceria with different morphologies are synthesized by hydrothermal method.The phase composition and surface morphology of them are characterized by X-ray diffraction and scanning electron microscopyand their mechanical polishing performanceare alsoinvestigated.In addition,the mechanical polishing modelsof micro/nano ceria with different morphologies are established by using Ansys,which is beneficial tofurther study the effects of morphology of micro or nano ceria on the mechanical polishing performance.Moreover,the polishing mechanism of micro or nano ceria in the process of mechanical polishing is also discussed.The spherical,cubic,and octahedralmicro or nano ceria are synthesized by hydrothermal method with ammonium ceric nitrate and urea,cerium nitrate and potassium hydroxide,cerium nitrate and ammonium acetate as reactants respectively.The polishing solutionsare prepared with three different morphologies of micro/nano cerium oxide as abrasive.Under the same polishing condition,the mechanical polishing experiment of monocrystalline siliconwas performed.The surface quality of single crystal silicon is characterized by optical microscope and scanning electron microscope.The results show that the polishing quality of the spherical micro cerium oxide is best,but the polishing efficiency is low;the polishing quality of the octahedral nano ceria is low,but the polishing efficiency is highest;while cubic nano ceria is between the two.In order to further study the polishing mechanism of micro/nano cerium oxide in mechanicalpolishing process,finite element software is used as the technical means to establishthe compressive stress distribution model of different morphologies of micro/nano ceria and single crystal siliconrespectively.The simulation results show thatin the case ofthe same morphology,the contact stress of differentcontact forms of polishing modelis completely different,andthe maximum contact stress of the point contact model is much greater than that of the line contact and the surface contact.In the same contact form,the contact stress ofdifferent morphology of cerium oxide polishing model is not the same.In the case of point contact,the contact stress and contact strain of the spherical cerium oxide polishing model are the smallest,and the mechanical polished silicon surface only appears small spots and shallow scratches,which suggests that spherical ceria is withgood polishing quality and low polishing efficiency.In the case of line contact,the contact stress and contact strain of the octahedral cerium oxide mechanical model are the largest,and the mechanical polished silicon surface has larger pits and deep grooves,which suggests that octahedral ceria is withlow polishing quality and high polishing efficiency.In the case of surface contact,the contact stress and contact strain of the octahedral cerium oxide mechanical polishing model are larger than those of the square shape.Besides,compared with the quality of silicon polished by square shape cerium oxide,the silicon polished by octahedral cerium oxide has bigger pits and deeper grooves,which suggests that the polishing quality of octahedral ceria is lower than cubic ceria but the polishing efficiency of octahedral ceria is higher.The polishing methodof micro/nano ceria withdifferent morphologiesis not the same in the mechanical polishing process.The polishing methodof spherical cerium oxide ismechanical attrition,and the polishingmethodsof cubic ceria and octahedral ceria are ploughingin the condition of the point or line contact but sliding cuttingin the case of the surface contact.