Investigation of immersion related defects using pre- and post-wet experiments

To evaluate the effect of water exposure to a resist stack a set of experiments was designed that introduce a pre- and post-exposure wetting time to a coated wafer. The ASML 1150i α-immersion scanner, integrated with a TEL-Lithius coater track, was used to investigate the formation of defects related to the extended wetting. In the first approach, wetting was achieved using a dynamic DI-water rinse in the developer module of the track. For the second approach the immersion hood was positioned over the wafer at a fixed position and time, subjecting the wafer area below the immersion hood to the flowing water. We investigated various resists and topcoats. Defect inspections were performed on these film stacks after imaging.