PFAS-free EUV rinse for advanced technology nodes

Abstract

Phasing out PFAS from semiconductor industry is a formidable undertaking driven both by sustainability concerns and by government regulations. Lithography process nowadays use PFAS-containing chemicals for rinsing the wafer at the end of the development process of chemically amplified resist patterned with EUV lithography. To evaluate the readiness and performance of novel PFAS-free alternative rinse liquids, we tested a concrete case of pitch 24 nm dense lines/spaces patterned on CAR by EUV lithography. In previous technological nodes, rinse performance was linked to the minimization of the capillary force acting in the liquid meniscus between lines; but in pitch 24 nm we found that model to be inadequate to explain the experimental observations. A larger design of experiment is proposed: by screening more than 25 rinse liquids of varying chemical composition we demonstration how each component of the rinse impacts the line breaks and pattern collapse probability, opening new ways to optimize the formulation of PFAS-free rinse.