Preparation Of Novel Abrasives And Their Applications In Chemical Mechanical Polishing For Cadmium Zinc Telluride Substrates

At present,infrared detection and high-energy ray detection occupy a pivotal position in aviation,aerospace,military defense and other strategic fields.Because of its high detection efficiency,wide band gap,high resistivity,good thermal stability and many other excellent physical and chemical properties,soft brittle crystal CdZnTe（CZT）has become the core material for the preparation of infrared focal plane epitaxial substrate and high-energy ray detector.However,the unique dissociation characteristics of CZT crystals greatly increase the difficulty of the processing of ultra-precision surface flatness,which limits the application and development of CZT crystals.In order to achieve ultra-smooth and ultra-low damage surface processing of CZT wafers,the morphology and structure of traditional spherical solid silica（sSiO₂）abrasive particles were modified and synthesized and CMP application was studied according to the dual coupling principle of abrasive mechanical grinding and chemical reagent etching in chemical mechanical polishing（CMP）process.The three-body wear behavior of the new type of composite abrasive particles during CMP processing and the equilibrium action mechanism coordinated with the corrosion and dissolution of chemical reagents were theoretically explored and revealed.For CZT soft material removal characteristics of brittle crystal easy dissociation,in this paper,the traditional sSiO₂ grits in the CMP process due to the small contact area and the weak elastic deformation caused by embedding,easily scratched problem,design and synthesis of a new kind of has a rod-shaped morphology and fine structure of mesoporous SiO₂（RmSiO₂）abrasive,and grinding grain length to diameter ratio and controllable,good morphology and uniform particle size.In addition,the pore structure and mechanical properties of the new RmSiO₂ abrasive particles were characterized and tested,and the correlation between the pore structure properties of abrasive particles and the elastic deformation behavior of abrasive particles was established.The conclusion was drawn that the mesoporous structure with dense and orderly pore distribution was more conducive to the enhancement of the elastic deformation ability of abrasive particles.By orthogonal test and extreme difference analysis,explores the abrasive mass fraction,volume of H₂O₂ content,ratio of polishing fluid factors such as p H and polishing pressure,rotating speed of pads,polishing process factors such as fluid flow regularity of influence on the properties of CZT crystals CMP proposed the CZT crystals CMP processing parameter optimization and the preparation of the new type of green environmental protection polishing solution methods.Based on the proposed new process and new polishing fluid,the CMP performance test of the new RmSiO₂ abrasive particles and the CMP comparison test of other abrasive particles with structure and morphology were carried out.According to the characterization results of roughness and material removal rate,it is concluded that the mesoporous abrasive has better performance than solid abrasive in ultra-precision surface machining.The morphology and structure of RmSiO₂ modified abrasives are better than that of single structure modified abrasives.By establishing the deformation contact theory model of RmSiO₂ abrasive in three-body wear system,the material removal mechanism of RmSiO₂ abrasive with low wear furrow wear effect and high adhesion wear and corrosion wear was reasonably revealed.In addition,the mechanism of chemical corrosion in the CMP process was also explored,and the interface reaction process of"H₂O₂ oxidation-tannic acid etching-tannic acid chelation"in the CMP process was proposed.Finally,based on the mechanical action of the new RmSiO₂ abrasive and the chemical action of the polishing liquefied chemical components,a synergistic mechanism was proposed to achieve ultra-precision surface machining of soft and brittle materials by balancing the elastic removal of abrasive and the corrosion and dissociation of chemical reagents.