Extension of optical crosslinking of EUV-compatible underlayers to PFAS-free and ArFi-compatible underlayers

BackgroundThe semiconductor industry faces mounting pressure to improve energy efficiency and reduce environmental impact as device dimensions continue to shrink and patterning complexity increases. Thermal crosslinking of spin-on carbon (SOC) and spin-on glass (SOG) underlayers is a particularly energy-intensive step due to high temperature requirements.AimWe extend our previously reported optical crosslinking approach, replacing conventional thermal baking with a high-dose optical curing system, to both extreme ultraviolet (EUV) and argon fluoride immersion (ArFi) lithography. We also introduce per- and polyfluoroalkyl substance (PFAS)-free underlayer formulations, designed to eliminate harmful fluorochemicals without sacrificing performance.ApproachComprehensive data on film crosslinking, lithographic performance, and energy savings are presented.ResultsOur optical crosslinking approach achieves energy savings of up to 85% for SOC and 60% for SOG in EUV processing and 75% and 60% for SOC and SOG, respectively, in ArFi processes. Furthermore, PFAS-free underlayers demonstrate competitive lithographic performance and robustness, comparable to conventional formulations.ConclusionsThese findings support a shift toward more sustainable semiconductor manufacturing by significantly reducing energy usage and eliminating environmentally harmful materials without compromising process performance.