Novel green chemical mechanical polishing of fused silica through designing synergistic CeO2/h-BN abrasives with lubricity

Abstract

It is a challenge to produce an atomic-scale surface of fused silica with a high material removal rate (MRR) using green chemical mechanical polishing (CMP). In traditional CMP, a slurry usually contains four or more components and is normally toxic and corrosive, causing environmental degradation. To address this problem, a novel green CMP slurry for fused silica was developed using ceria/hexagonal boron nitride (CeO2/h-BN) abrasives, potassium oleate, and deionized water. Due to the two-dimensional nanosheet structure of h-BN, it is simple to generate a sheared layer, which lowers friction at the contact area. Ceria abrasives realized a new function for superlubricity during CMP through this design, preventing damages and reaching atomic-scale surface. This is confirmed by research showing that a damaged layer’s thickness following CMP, as determined by high-resolution transmission electron microscopy, is only 2.7 nm. The MRR of fused silica is 31.92 µm•h−1 during CMP, and surface roughness Sa is 0.124 nm after CMP. The MRR is currently at its highest with such a low surface roughness. These findings provide a new pathway to achieve an atomic-scale surface for a hard-brittle material with a high MRR using the synergistic effect of abrasives.