Atomic-scale planarization surface of quartz glass induced by novel green chemical mechanical polishing using three ingredients

Abstract

Traditional chemical mechanical polishing (CMP) usually employs more than three kinds of toxic or corrosive ingredients for its slurry. Quartz glass is a hard-brittle solid, and it is extremely difficult to achieve its atomic-scale planarization surface. In these respects, it is a challenge to obtain atomic surface of quartz glass using green CMP slurry with three ingredients. To solve this challenge, a novel green CMP was developed, containing three green ingredients, such as ceria, sodium alginate and aminobutyric acid. After CMP, atomic surface is acquired with surface roughness Ra of 0.093 nm and material removal rate of 12.47 μm/h. Transmission electron microscopy confirms the thickness of damaged layer is 8.57 nm. X-ray photoelectron spectroscopy shows that –OH, C–N and –COOH groups adsorbed on the surface of quartz glass after immersion in CMP slurry, which agrees well with the simulated results of molecular dynamics. Density functional theory calculations reveal that electron transfer groups of aminobutyric acid and sodium alginate were predominantly located on –NH2 and –COOH, forming the covalent bonds between them. Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy indicate that new complexes were generated between aminobutyric acid and sodium alginate, increasing the viscosity of CMP slurry. Furthermore, the breakage of C–N and O–H bonds after CMP suggests that the complexes play a pivotal role in the CMP process. The developed novel green CMP with three ingredients provides new viewpoints to obtain atomic-scale planarization surface for a hard-brittle solid.