Material Development for ArF Immersion Resist Extension

ArF immersion process is being widely applied for advanced device manufacturing. ArF immersion lithography can cover 4x nm hp lithography. In addition, double patterning process allows extendibility towards 2x nm hp lithography. From the point of view of photoresist, it is utterly important for materials to bring out the maximum performance of ArF immersion process. In this study, we focused on photoresist development and substrate optimization, demonstrating good lithographic performance of sub-40nm hp resolution with well controlled line width roughness (LWR). First of all, we studied photo acid generator (PAG) behavior focusing on shortening acid diffusion length during Post Exposure Bake (PEB). Secondly, high dissolution contrast polymers in which dissolution properties are changed by acid catalyzed reaction through exposure and PEB are being studied. Thirdly, reflectivity control from substrate through optimization of light intensity over resist film thickness has been carried out. In this report, we have achieved 36.5nm line and space (LS) resolution with LWR of less than 10% of patterned critical dimension (CD). This achievement is very useful especially when utilized in combination with process tricks such as multiple patterning for extending existing ArF immersion lithography towards sub-20nm hp lithography.