A New Dry Etching Method with the High Etching Rate for Patterning Cross–Linked SU–8 Thick Films

Photo sensitive polymer SU-8, owing to its excellent mechanical properties and dielectric properties on polymerization, is widely used in MEMS device fabrications. However, the removing, stripping or re-patterning of the cross-linked SU-8 is a difficult issue. In this paper, CF₄/O₂ gas mixture provided by a plasma asher equipment was used for the patterning of cross-linked SU-8 material. The RF power, the temperature of the substrate holder, chamber pressure and gas concentration were optimized for the cross-linked SU-8 etching process. When the CF₄/O₂ mixture contains about 5%CF₄ by volume, the etching rate can be reached at 5.2 μm/min.