Supercritical drying for nanostructure fabrication without pattern collapse

Supercritical drying has been proposed for the fabrication of nanostructures made up of silicon or resist. Pattern collapse, which is a very serious problem in the fabrication of fine patterns, is related to the spacing, the aspect ratio and the surface tension of rinse solution. Among them, surface-tension reduction is the most effective way to reduce pattern collapse, because it is independent of pattern size. Using supercritical carbon dioxide, which is completely free of surface tension, as a final rinse, we have obtained silicon patterns without collapse. For resist, we have found that avoidance of water contamination is the key factor in suppressing pattern deformation in supercritical drying. Consequently, a drying technique which results in resist patterns without pattern collapse and deformation has been proposed.