Impact of developer chemistry on EUV photolithography defects: PFAS vs. PFAS-free surfactants

EUV photolithography plays a major role in developing features critical for sub-nm nodes. In photolithography development, the developer process and chemistries help create defect-free patterns. Developer performance is impacted by the EUV photoresist (PR), which is known to be hydrophobic and become hydrophilic post-exposure. The developer process for high aspect ratios patterns includes TMAH, surfactant, conditioning rinse R1, and DI water rinse to develop and clean the developer by-product. The type of the developer and the rinse have a significant impact on the developer process optimization. Pattern collapse is a major challenge for the high aspect ratio photolithography levels. Pattern collapse occurs due to increased surface tension of the fluid during the developer process which significantly degrades pattern performance and yield. Surfactant-based developer helps in improving the wettability of the developer on the resist surface during pattern development. One of the industry’s challenges is to replace the photolithography PFAS surfactant rinse with the non-PFAS alternatives. This work discusses the photolithography defectivity performance, comparing the PFAS vs PFAS-free surfactant rinse for high aspect EUV dense L/S photolithography pattern development.