Super-contrast-enhanced darkfield imaging of nano objects through null ellipsometry

We rediscover the null ellipsometry principle for an outstanding image-contrast enhancement method for darkfield imaging. Simply by adding polarizers, compensators, and a photodiode sensor to a conventional darkfield imaging system and applying the null principle, Si nano-cylinder structures as smal...

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Bibliographic Details
Published in:Optics letters 2018-12, Vol.43 (23), p.5701-5704
Main Authors: Cho, Seongkeun, Lee, Janghwi, Kim, Hyungu, Lee, Seulgi, Ohkubo, Akinori, Lee, Jungchul, Kim, Taehyun, Bae, Sangwoo, Joo, Wondon
Format: Article
Language:English
Subjects:
Compensators
Cylinders
Defects
Ellipsometry
Image contrast
Image enhancement
Photodiodes
Polarizers
Silicon
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Summary:We rediscover the null ellipsometry principle for an outstanding image-contrast enhancement method for darkfield imaging. Simply by adding polarizers, compensators, and a photodiode sensor to a conventional darkfield imaging system and applying the null principle, Si nano-cylinder structures as small as D20 nm (H20 nm) on non-patterned wafer, and gap defects as small as 14.6 nm and bridge defects as small as 21.9 nm on 40 nm line and 40 nm space patterns (H40 nm), which are invisible in conventional darkfield imaging, can be distinguished from scattered noise. To the best of our knowledge, no method has been successful for identifying such small non-metal (silicon) nanoscale objects with such low magnification (×20) optics.
ISSN:0146-9592
1539-4794
DOI:10.1364/OL.43.005701