Oxygen Vacancy Engineering in Co-Doped CeO2 for Silica Wafer Polishing

The exploitation of nanostructured abrasives with a high removal rate (RR) and high surface quality is crucial for achieving effective chemical mechanical polishing (CMP) of silica wafers. While traditional abrasives such as micron-sized SiO₂ exhibit low RR, nanoscale CeO₂, known for its enhanced polishing efficiency, surface quality, and process control, lacks systematic studies to fully understand and optimize its performance in CMP applications. In this research, uniformly dispersed CeO₂ nanoparticles doped with transition metal Co were meticulously designed and prepared by a one-step hydrothermal method. The nanoscale characteristics of Co-doped CeO₂ abrasives, including their particle size distribution and surface reactivity, were systematically investigated. The RR of the silica wafer experienced a substantial increase from 1737 to 2451 Å/min, representing a notable rise of about 40%. Additionally, superior surface quality (Sq = 0.0819 nm) was achieved. This remarkable enhancement was attributed to the nanostructure and Co doping, which facilitates silica wafer removal by increasing oxygen vacancies and the Ce³⁺ content in ceria, thereby boosting the efficiency of silica removal through enhanced nanoscale chemical interaction between the abrasive and wafer surface. This innovative concept of utilizing Co-doped CeO₂ nanoparticles presents a synergistic strategy for the effective removal of silica wafers, offering promising implications for the application of the CMP in the field of integrated circuits.