Molecular Dynamics Simulation of Nano-Defects on Fused Silica Surface Induced by Low-Temperature Plasma Cleaning

Low-temperature plasma cleaning technology has been widely used to clean various optical components precisely. After the complete removal of organic contaminants from fused silica surfaces through plasma cleaning, continuous plasma irradiation can lead to nano-defects on the fused silica surface, resulting in the degradation of optical performance. Thus, the microscale processes underlying plasma-induced surface damage on fused silica were investigated through molecular dynamics simulations, aiming to analyze the mechanisms of surface damage on optical components during plasma cleaning. Oxygen plasma bombardment disrupted fused silica bonds, leading to the successive sputtering of silicon-oxygen atoms. The quantity of sputtered silicon atoms demonstrated a linear correlation with irradiation time. The emergence of pit defects and distinctive interface damage patterns elucidated the impact of neutral oxygen atoms. Critical findings underscore the onset of significant damage beyond 33 eV, underlining plasma's role in thinning fused silica. Temperature is a crucial factor affecting surface damage during plasma cleaning. Ultimately, investigating the surface damage mechanism of fused silica during plasma cleaning establishes a groundwork for achieving non-destructive optics cleaning.