Rapid Supercritical Drying Techniques for Advanced Lithography

摘要

A rapid supercritical drying process for resist patterns has been developed that features three novel techniques: the removal of rinse water based on a difference in specific gravity, rapid heating with a hot wafer holder, and the rapid release of supercritical fluid using helium. These techniques are efficient and cause no damage to resist patterns because no harmful chemicals, such as surfactants, are used. In addition, the effectiveness of these techniques has been demonstrated on several types of resists: polyhydroxystyrene-based, methacrylate-based, and fluoropolymer-based resists, which are used in 248-nm (KrF), 193-nm (ArF), and 157-nm (F_2) lithography, respectively. The release time for helium is less than 30 seconds. The short time needed for this supercritical drying process makes it very practical for both current and next-generation lithography.