Actinic critical dimension measurement of contaminated extreme ultraviolet mask using coherent scattering microscopy

Vac. Sci. Technol. B 32, 031601 (2014).

Jae Uk Lee1, Seongchul Hong1, Jinho Ahn 1,a), Jonggul Doh2 , SeeJun Jeong3


1 Department of Materials Science and Engineering, Hanyang University, Seoul 133-791, South Korea and

2 Mask Development Team, Semiconductor R&D Center, Samsung Electronics, Co., Ltd., Hwasung, Gyeonggi 445-701, South Korea and

3 Department of Convergence Nanoscience, Hanyang University, Seoul 133-791, South Korea.




The authors evaluated the feasibility of using coherent scattering microscopy (CSM) as an actinicmetrology tool by employing it to determine the critical dimension (CD) and normalized image log-slope (NILS) values of contaminated extreme ultraviolet (EUV) masks. CSM was as effective as CD scanning electron microscopy (CD-SEM) in measuring the CD values of clean EUV masks in the case of vertical patterns (nonshadowing effect); however, only the CSM could detect shadowing effect for horizontal patterns resulting in smaller clear mask CD values. Owing to weak interaction between the low-density contaminant layer and EUV radiation, the CSM-based CD measurements were not as affected by contamination as were those made using CD-SEM. Furthermore, CSM could be used to determine the NILS values under illumination conditions corresponding to a high-volume manufacturing tool.


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