How to achieve tip-to-tip patterning beyond the resolution limit: gas cluster beam (GCB) directional etch for sub-15nm T2T metal PnR with 0.33 NA EUV single print

This study explores the potential of 0.33 NA (low-NA) EUV lithography for single-patterned 28nm pitch (P28) structures using a Bright-Field (BF) mask and spin-coated Metal Oxide Resist (MOR). The evaluation of a low-n type mask demonstrated significant improvements in Local Critical Dimension Uniformity (LCDU) and optical image contrast compared to traditional Ta-based masks. These enhancements contribute to better pattern fidelity and reduced lithographic error, highlighting the advantages of using advanced mask types for next-generation semiconductor manufacturing. For 28P logic use cases, the T2T CD control recently drew attention. The implementation of a T2T push process using the directional etch technology is discussed. The T2T CD can be trimmed up to ~10 nm to help meeting the T2T CD requirement of the P28 technology. Some initial results on high-NA EUV P28 and P24 wafers indicate this directional etch technology can be applied and can complement the T2T patterning. Following a holistic approach of the process development, defectivity on random logic clips is also implemented to assess their patterning limitation and be used to further help co-optimizing the whole patterning process. The findings underline the importance of optimizing lithographic processes for achieving smaller and more precise features, that are crucial for scaling down device nodes in future semiconductor technologies.