Femtosecond HHG-Based Actinic EUV Exposure Platform for Quantitative Photoresist Evaluation
Abstract
For EUV lithography, reliable actinic photoresist evaluation is essential for addressing stochastic variation and secondary-electron-driven reactions. Here, we present a laboratory-scale EUV photoresist sensitivity measurement (EPSM) system based on a femtosecond high-harmonic generation (HHG) source delivering 13.5 nm actinic EUV radiation. To overcome the intrinsically low photon flux and tightly focused Gaussian beam profile of tabletop HHG sources, controlled scanning-based exposure was implemented through precise scan distance and scan speed control, enabling uniform and reproducible areal irradiation. Using hydrogen silsesquioxane (HSQ) as a benchmark negative-tone photoresist, strong agreement between simulated dose distributions and atomic force microscopy measurements was achieved, validating the scanning-based exposure approach. Quantitative contrast-curve analysis was demonstrated using HSQ and PMMA as benchmark photoresists. By integrating controlled scanning with actinic EUV exposure, the EPSM provides a versatile actinic platform for quantitative photoresist evaluation and offers a basis for future studies of stochastic effects, secondary-electron processes, and EUV patterning.
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