Roles of colloidal silicon dioxide particles in chemical mechanical polishing of dielectric silicon dioxide

Chemical mechanical polishing (CMP) is carried out using slurry particles in contact with a wafer and a pad. The size and distribution of particles between the wafer and the pad play a crucial role in achieving desired CMP performance. Polishing rates and friction forces were measured as a function of particle size and solids loading, and surface finishes of silica wafers polished with colloidal silica particles were analyzed to validate the polishing mechanism. On the basis of polishing rate, friction force and surface finish, polishing occurring at the pad-particles-wafer interface was analyzed and an interfacial contact model was proposed. Understanding the polishing mechanism using colloidal particles makes it possible to achieve desired CMP performance.