Fabrication and application of micro tapered structure by proximity backside exposure

In this paper, the fabrication method of high aspect ratio tapered structure is proposed by using chemically-amplified epoxy-based negative resist SU8. Proximity exposure technique is used from the backside of 150μm thick glass substrate to change the amount of exposure by using conventional mask. The amount of exposure was transformed into micro tapered resist structure. Slit pattern from 5μm to 35 μm width was designed and exposed, the difference of exposure amount causes the resist height change from 25μm to 180μm. Polydimethylsiloxiane (PDMS) surface was transformed from the resist structure in order to improve the water-repellency. The repellency was highest at the diameter of 20μm, and the maximum contact angle was 172° and 165° on the average.