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Extreme Ultraviolet (EUV) lithography poses an ever greater challenge to RLS (resolution, line edge roughness, and sensitivity) than previous photolithography methods as lithographers try to achieve sub-14nm pitch in a single-exposure. Additionally, EUV is particularly susceptible to stochastic imaging defects. Although standard chemically amplified resists (CARs) can be exposed with EUV, these materials struggle to achieve resolution targets at manufacturable doses due to limitations in laser source power and resist sensitivity and contribute to stochastics by nature of their random distribution of components. An innovative approach with Inpria Metal Oxide Resists (MORs) can offer an alternative to overcome both EUV resolution and sensitivity limitations, as well as address stochastic defects. On the other hand, traditional sources of defectivity, such as particles, present another challenge, especially when moving toward high-volume manufacturing. Ultrahigh molecula r weight polyethylene (UPE) membrane filters have been used for metal oxide EUV resist filtration because of their high retention efficiency and excellent photochemical compatibility. However, newly designed UPE filters with innovative membrane morphology are needed to further lower defectivity rates with these new resists. This paper describes efforts to continue to improve metal oxide EUV resist defectivity through filtration optimization. A comparative study of the patterning performance of various Point-of-Use (POU) filters is presented. Several filters utilizing a variety of retention ratings and membrane designs were installed on a TEL Clean TrackTM Lithius ProTM Z series. A metal oxide EUV resist was filtered and coated on wafers that were subsequently analyzed for patterning defect performance. This study examines the efficacy of optimized filtration design to reduce defects and provides a recommendation to achieve lower defect density.
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