Development and Performance Evolution of Medium-Pressure Plasma Process for Surface Modification of Fused silica

Abstract

A novel non-contact medium-pressure plasma nano-finishing technique is being developed to augment or replace chemo-mechanical polishing (CMP) techniques for finishing such microstructures. The developed process uniformly polishes the complex-shaped gyro, i.e., a hemispherical resonator shell fabricated with fused silica by an ultrasonic milling process. A combination of plasma polishing and cleaning processes is used to achieve sustained polishing of the hemispherical shell. It is essential to understand the brittle damages, such as surface cracks and plastic deformation, that can occur on the surface of hard, brittle materials like glass ceramics, fused silica, etc. The novelty of the present medium-pressure plasma process is that it combines the isotropic material removal capability of low-pressure plasma and the atomistic material removal capability of atmospheric-pressure plasma. This process can simultaneously polish entire complex 3D surfaces, including cavities where no tool or beam can reach.