Pattern collapse in high-aspect-ratio DUV and 193-nm resists

ABSTRACT The pattern collapse behavior of a set of 193nm resists in high aspect ratios was quantified. For all the resists investigated ageneral behavior could be observed: the collapse did not only depend on aspect ratio but also on pitch. With higher aspectratio/pitch (normalized aspect ratio: NAR) all the resists go in a sigmoidal step from no collapse to total collapse. Surfactantsin the developer did not have a consistent effect on pattern collapse. Resists of different polymer structure showed a verydifferent tendency to collapse: acrylic resists collapse earlier than cyclo-olefinic resists. It could be deduced that patterncollapse will be a significant problem starting at the l3Onm node, if the film thickness range of the SIA roadmap aremaintained. Comparison with data obtained for DUV resists showed that pattern collapse might limit the application of DUVresists in NGL. The modeling work at the University of Wisconsin shows the big impact of thermo-mechanical thin filmproperties on the pattern collapse problem.