Extending a 193 nm mask inspector for 22 nm HP EUV mask inspection

Reticle quality and the capability to qualify a reticle remain key issues for EUV Lithography. In this paper, we report on recent advancements that extend the capability of a 193 nm mask inspector to meet requirements for the 22 nm HP / 15 nm Logic node. This work builds upon previous work that was published earlier this year, by D. Wack 1 , et. al. Meeting these requirements requires development of a number of novel capabilities for mask inspection, including the use of offaxis illumination, various polarization modes, and use of an optimized absorber stack for EUV masks. In addition, we discuss the challenges of inspecting EUV masks in die-to-database mode, and how tone inversion can be successfully modeled. Lastly, we show that this same 193 nm mask inspector, with the use of proprietary algorithms, can be extended to meet industry requirements for EUV phase defect blank inspection.