Multiscale analysis of surface pit defect formation in chemical mechanical polishing of AlN single crystals

Abstract

Surface pit defects emerging during chemical mechanical polishing (CMP) of aluminum nitride (AlN) single crystals critically compromise device reliability. In this study, we develop a multiscale correlation model linking mechanical load, stress relaxation, dislocation evolution, and defect formation to elucidate the mechanisms and evolution pathways of these defects. In situ nanoindentation and polishing experiments reveal the governing role of mechanical loads. These loads control the elastoplastic deformation behavior of AlN crystals. Abaqus finite element simulations combined with wafer cleavage experiments characterize the three-dimensional stress distributions during abrasive indentation, demonstrating that residual stress relaxation predominantly drives defect morphology evolution. Additionally, atomic force microscopy scratch experiments uncover a dislocation slip-induced lattice distortion process at the microscale. Photoluminescence spectroscopy further confirms that Zr_Al-V_N composite defects—formed via abrasive embedding under chemo-mechanical synergy—induce emission peak broadening, highlighting the catalytic role of abrasive–substrate chemical bonding in defect evolution. This multiscale approach overcomes traditional single-physics limitations. It provides a comprehensive framework for damage control in ultra-precision machining of wide-bandgap semiconductors.