Comparative first-principles analysis of crystalline versus amorphous CeO₂ particles: implications for chemical mechanical planarization

Based on density functional theory (DFT) calculations, we first examine a detailed study of CeO₂ in both crystalline and amorphous forms, assessing their structural, electronic, mechanical, and surface characteristics for chemical mechanical planarization (CMP). We explored the atomic structures of CeO₂, uncovering distinct atomic configurations and consistent bonding in both phases. The crystalline form of CeO₂ is characterized by a distinct bandgap of 1.84 eV and a higher degree of stiffness, evidenced by a bulk modulus of 178.10 GPa. Conversely, the amorphous phase of CeO₂ features a smaller bandgap, measured at 1.39 eV, and a reduced stiffness with a bulk modulus of 155.13 GPa, beneficial for reducing CMP scratches. Notably, the amorphous CeO₂ forms oxygen vacancies more readily, leading to a higher concentration of Ce³⁺ ions, lower surface energy (0.92 J/m²), and enhanced adhesion with SiO₂ (adhesion work of 0.73 J/m²) compared to crystalline CeO₂. Our DFT calculations reveal the unique physicochemical properties of amorphous CeO₂, such as its softer nature and stronger SiO₂ adhesion, providing valuable insights for optimizing CMP processes.