A New Negative-Tone, UV Lithography Photoresist for Fabrication of Ultra-High-Aspect-Ratio Microstructures

Abstract

We report a new type of negative-tone photoresist in this paper. The resist is based on the composite of EPON resins 154 165 (both from Hexion Specialty Chemicals, Inc., Columbus, OH 43215). These two epoxy resins were mixed in an optimal ratio and dissolved into the gamma-butyrolactone (GBL) solvent. The mixture was then photosensitized by adding a given amount of triaryl sulfonium salt to obtain the new negative tone photoresist that can be used in for ultra high aspect ratio microstructures with UV lithography. The preliminary study has found that microstructures with height of more than 1000 μm and feature sizes of 10 μm (aspect-ratios of more than 100) can be obtained using the new resist film with ultraviolet lithography. The microstructures have excellent sidewall quality. In this paper, both the material properties and lithography properties of this new type of UV resist will be presented. The potential applications of the new resist in microfabrication and MEMS systems are also discussed.