Mechanism of chemical and mechanical mutual promotion in photocatalysis-assisted chemical mechanical polishing for single-crystal SiC

Abstract

Single-crystal SiC has become the third-generation semiconductor material with the most development potential due to its many outstanding physical and chemical properties, but excellent surface quality is the prerequisite for its application. Therefore, atomic mechanism of chemical and mechanical mutual promotion in hydroxyl radical ·OH aqueous was researched through reactive molecular dynamics simulation for obtaining nano-smoothed surface with photocatalysis-assisted chemical mechanical polishing (PCMP). The behavior of nanoparticles promoting chemical reaction during the nanofinishing process was studied vias a single abrasive sliding on the surface of SiC. A combination method of mechanical action and chemical action was adopted to compare effect of material oxidation and material removal. Si/C atoms are mainly fractured or escaped in the forms of SiO, CO, chain, SiO2, and CO2, and more residual oxidation products were observed on the substrate. Furthermore, XPS and nanoindentation results also support the mechanism of chemical and mechanical mutual promotion in PCMP through the detection of the oxidized products and surface hardness. This process activated and removed the SiC materials and generated a smooth and non-damaged surface (Ra 0.269 nm and Rmax 0.807 nm). The research results may reveal the removal mechanism of Si/C atoms, and provide new theoretical and technical support for the ultra-precision machining of single crystal sapphire, silicon nitride and diamond etc.