High-Aspect-Ratio Patterning of Thick Polyimide Film by N₂ Ion Beam Etching

Abstract

A high-aspect-ratio and precise patterning of thick polyimide film has been achieved using a 50-μm-thick polyimide film masked by 0.1-μm-thick Ta film. The film was etched by a low-energy N₂ ion beam with a single-grid Kaufman-type ion source. The selective ratio of the polyimide film vs. the Ta film reached more than 600. The wall angle of the polyimide pattern was about 2°. Etching rate experiments and XPS, FTIR, AFM analysis suggest that N₂ ion beam etching is a reactive ion etching.