High-efficiency submerged air jet chemical mechanical polishing at the atomic and close-to-atomic scale

Abstract

Fluid jet polishing (FJP) has demonstrated significant potential for polishing and figuring of surfaces with complex geometries owing to its flexibility and shape-adaptive capacity, particularly in high-precision optical applications such as X-ray reflectors, extreme ultraviolet lithography, and super-resolution imaging. Despite its advantages, FJP faces two major challenges that hinder its large-scale industrial adoption. The first challenge is the trade-off between surface quality and material removal efficiency. FJP relies solely on the mechanical impacts of abrasives for material removal, leaving erosion pits on the polished surface. Consequently, existing techniques struggle to achieve sub-nanometer precision while maintaining efficient material removal rates. The second challenge arises from the brittle fracture of materials during the FJP process, complicating the achievement of ultra-smooth surfaces with minimal subsurface damage. To address these limitations, this study introduces Submerged Air Jet Chemical Mechanical Polishing (SAJCMP). This method incorporates a novel material removal mechanism, referred to as “nano-reactive-abrasive-laden droplet-induced chemical mechanical removal,” which enables atomic and close-to-atomic precision while significantly improving polishing efficiency. The multi-scale material removal mechanism is elucidated through both experimental investigations and molecular dynamics (MD) simulations. Furthermore, the influence of various polishing parameters on the synergistic effects of chemical and mechanical actions is analyzed using computational fluid dynamics (CFD) simulations, complemented by experimental validation. Polishing experiments conducted on structured arrays and curved surfaces demonstrated that SAJCMP significantly enhances surface quality, preserves form accuracy, and minimizes subsurface damage.