Novel depolymerizable topcoat for immersion lithography

In this paper, we present a new type of depolymerizable topcoat for immersion lithography that rapidly dissociates into water soluble sub-units during the develop process step. Such chemistry enables the synthesis of very hydrophobic topcoat which may have an advantage in reducing watermark defects. We investigated the impact of different developer formulations and various acid catalysts in the topcoat formulations on the polymer dissolution rate and lithography performance. The data showed larger process windows for this novel topcoat compared to the baseline topcoat.