Resist Stripping and Surface Cleaning Technique Using High Speed Steam-Droplet Mixture

A novel resist stripping and surface cleaning technique is proposed. We have improved wet vapor resist stripping technique (Ojima & Ohmi) using high-speed steam and purified water droplets mixture. Relatively low pressure steam (0.1MPa∼0.2MPa) is mixed with purified water in front of the nozzle, and sprayed to Si wafer with resist. Using this new technique, we are able to strip resist without chemicals very quickly and also to clean a wafer surface, i.e., to eliminate some particles. This technique has an advantage not only in reducing some processes of semiconductor manufacturing but also in maintaining chemical-free environment. Both droplet velocity and diameter distributions were measured by Phase Doppler Anemometer (PDA). Resist stripping was observed with a high-speed video camera and the fringes of the removed resist region were observed with a digital microscope. Mechanism of this resist stripping process is discussed.