A NEW DRY ETCHING METHOD WITH THE HIGH ETCHING RATE FOR PATTERNING CROSS-LINKED SU-8 THICK FILMS

Jingning Han – Zhifu Yin – Helin Zou – Wenqiang Wang – Jianbo Feng

   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, CF₄O₂ 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 CF₄O₂ mixture contains about 5 % CF₄ by volume, the etching rate can be reached at 5.2 μm/min}$.

Keywords: dry etching, plasma, SU-8 photoresist, etching rate

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