Advanced Wafer Drying Technology for 1x Node and Beyond Using Surface Modification Method

Abstract

IPA dry has been used as a method to prevent pattern collapse instead of spin dry since it is easy to install for single wafer tools. However, it is reaching the limit of process margin since IPA surface tension is only one third that of water. We focused on the other parameter which decides Laplace force: contact angle. When the contact angle is close to 90deg, the force approaches zero, which enables larger process margin for next generation structures. We call this concept of drying ‘Monolayer Dry’. We compared the potential of IPA dry, F-based solvent (with very low surface tension) and Monolayer Dry by calculating the threshold aspect ratio (AR) of generating pattern collapse. Compared the performance of Monolayer Dry to IPA dry by observing the cross-section surface after cleaning and drying. No collapse was found by Monolayer Dry using 1x node pattern sample.