Advances in surfactants for photolithography

The advancement of dense integrated circuits requires the miniaturization of feature sizes, which has driven continuous progress in photolithography. However, there are still some challenges in achieving a high patterning resolution for photolithography such as surface contaminants, defect formation, pattern collapse, etc. Surfactants have been extensively investigated for several decades as essential wet chemicals to resolve these issues due to their outstanding performance in reducing surface tension, enhancing wettability, and improving solubility. Recently, it has been revealed that surfactants with diverse chemical structures can exhibit distinct functionalities at various stages of the photolithography process, yet comprehensive discussions on their structures, performance, and mechanisms remain limited. In this review, we first address the structure-performance relationships for anionic, cationic, nonionic, and zwitterionic surfactants and then provide a general introduction to photolithography from a historical and technological perspective. Specifically, various surfactants used as additives in cleaners, developers, etchants, and strippers for photolithography are thoroughly summarized and discussed, where their key parameters, used concentrations, and underlying mechanisms have been introduced to provide a valuable guide for future research. Finally, we propose three strategic directions for the development of innovative surfactants to address emerging challenges and drive sustainable progress in photolithography: (1) high-performance surfactants, (2) switchable surfactants, and (3) bio-based surfactants.