Effect of pellicle wrinkles on EUV reflectivity and local critical dimension

Seungchan Moon; Dong gi Lee; Jinhyuk Choi; Jinho Ahn

doi:10.1117/12.2655991

14 April 2023 Effect of pellicle wrinkles on EUV reflectivity and local critical dimension

Seungchan Moon, Dong gi Lee, Jinhyuk Choi, Jinho Ahn

Proceedings Volume PC12494, Optical and EUV Nanolithography XXXVI; PC124940F (2023) https://doi.org/10.1117/12.2655991
Event: SPIE Advanced Lithography + Patterning, 2023, San Jose, California, United States

Conference Poster

Abstract

EUV pellicle has been actively researched as a solution for defect mitigation of EUV mask. Its EUV reflectance (EUVR) less than 0.04% is strictly required to prevent critical dimension drop (ΔCD). But high-power EUV in the scanner can induce the occurrence of wrinkles on the pellicle and it can affect the optical properties of pellicle like EUVR. In this study, we experimentally investigated the change of EUVR induced by the pellicle wrinkles and its effects on mask imaging performance with EUV ptychography microscope, an actinic inspection tool using coherent EUV light source from high harmonic generation. As a result, we confirmed not only a local increase of EUVR (approximately 4 times) but also randomly changed beam path of the reflected light by the wrinkle. To confirm the effect of those reflected light from the wrinkle on mask imaging performance, we reconstructed the aerial images using a ptychographic algorithm after synthesizing the reflected EUV light into a contact hole mask diffraction pattern. As the aerial image is obtained by superposing the diffracted light, the mask imaging performance can be variated by synthesized EUV light. The reflected light near 1st order diffraction pattern affects CD resulting from its spatial frequency, whereas the reflected light near 0th order diffraction pattern works as noise causing contrast loss. Eventually, ΔCD as large as 6 nm was observed. Therefore, even if the pellicle satisfies the EUVR requirement, we need to tightly control the generation of wrinkles to suppress CD variation during the exposure process.

Citation Download Citation

Seungchan Moon, Dong gi Lee, Jinhyuk Choi, and Jinho Ahn "Effect of pellicle wrinkles on EUV reflectivity and local critical dimension", Proc. SPIE PC12494, Optical and EUV Nanolithography XXXVI, PC124940F (14 April 2023); https://doi.org/10.1117/12.2655991

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