UV-assisted intermittently-spinning ozone steam etching of SU-8 for micromolding process

This study reports on the usability of ultraviolet (UV)-assisted ozone steam etching for SU-8 removal in micromolding process. SU-8 is etched at a rate greater than 100 nm/min by intermittently rotating a substrate on a spinner with UV irradiation to spin out etching products. Its complete removability was also verified by analyzing the substrate surface after the ozone steam etching of SU-8 via scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). In a micromolding process, non-swelling removal of a 20-μm-thick SU-8 mold successfully left electroplated mushroom microstructures without destroying or residue. Such a structure cannot be released by conventional resist strippers, because it is lifted up due to resist swelling. Therefore, our new resist removal method is clearly demonstrated to have the usability and applicability for the micromolding process.