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28 September 2019 Through-pellicle imaging of extreme ultraviolet mask with extreme ultraviolet ptychography microscope
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Background: An extreme ultraviolet (EUV) pellicle is necessary to increase the process yield even though the declining throughput is a big concern. However, an EUV metrology/inspection tool for this pellicle has not been commercialized yet.

Aim: The goal of this study is to verify the pellicle/mask inspection feasibility of EUV scanning lensless imaging (ESLI) and verify the impact of contaminants on pellicles depending on their size.

Approach: Through-pellicle imaging was implemented by using ESLI, which uses a high-order harmonic generation EUV source and ptychography. Optical characteristics of various sizes of Fe-contaminated EUV pellicles were evaluated to verify their impact on wafer images.

Results: Large size (∼10  μm) contaminants on the pellicle were found to contribute to the final wafer pattern loss. However, small size (2 to 3  μm) contaminants on the pellicle do not have substantial impact on the wafer image.

Conclusions: The defect detection capability of ESLI for pellicle and mask was confirmed. Therefore, ESLI is useful in applications like pellicle qualification and EUV mask inspection metrology.

Dong Gon Woo, Young Woong Kim, Yong Ju Jang, Seong Ju Wi, and Jinho Ahn "Through-pellicle imaging of extreme ultraviolet mask with extreme ultraviolet ptychography microscope," Journal of Micro/Nanolithography, MEMS, and MOEMS 18(3), 034005 (28 September 2019).
Received: 8 July 2019; Accepted: 29 August 2019; Published: 28 September 2019


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