Supercritical resist dryer

We have developed a supercritical resist dryer in which resist patterns are developed and successively dried with a supercritical fluid. The usage of supercritical fluid in pattern drying is most effective for preventing pattern collapse, which is a significant problem in fine patterning of less than 100 nm critical dimensions. The key to performing ideal supercritical resist drying is the prevention of water contamination due to moisture in the dryer chamber. This is because the moisture dissolved in the supercritical fluid causes pattern deformation which results from film swelling. As a technique to prevent water contamination, we have devised pressure-controlled supercritical drying where a supercritical fluid is sent pressurized to a Teflon coated chamber at near the critical point. The supercritical resist dryer made on the basis of this technique is an essential apparatus for next-generation lithography.