A Novel Approach Using Environmental Sustainable Technologies in Wet Processing Tools for Waste Reduction

In response to increasing environmental and health regulations restricting hazardous chemicals such as N -methyl-2-pyrrolidone (NMP) and tetramethylammonium hydroxide (TMAH), this study investigates an alternative, environmentally friendly approach for photoresist stripping and organic particle removal using oxidizing media activated by in situ UV light (ISUV). Originally developed for photomask cleaning, the ISUV process was adapted and evaluated on wafer-level using a prototype spin chuck system with integrated UV light sources. Positive and negative tone resists were tested to assess strip rates, cleaning performance, and surface preservation. A design of experiments (DOE) revealed that lamp power, media temperature, and rotation speed significantly influence process efficiency, with optimal conditions achieving resist removal rates up to 600 nm/min. Furthermore, the type of oxidant was altered from hydrogen peroxide to ozone. ISUV-based cleaning also demonstrated very good organic particle removal and lower surface impact compared to plasma post-cleaning under laboratory conditions using manual inspection tools. Furthermore, wastewater analysis confirmed the decomposition of organic residues to CO 2 and H 2 O, with no detectable increase in harmful by-products, highlighting the green potential of the process. Overall, ISUV activation presents a promising alternative to conventional wet and plasma cleaning techniques, offering both environmental and operational benefits.