Open AccessDiffraction-based overlay metrology using angular-multiplexed acquisition of dark-field digital holograms
Author(s) -
Christos Messinis,
T.T.M. van Schaijk,
Nitesh Pandey,
Vasco T. Tenner,
Stefan Witte,
Johannes F. de Boer,
Arie den Boef
Publication year - 2020
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.413020
Subject(s) - metrology , overlay , optics , holography , multiplexing , digital holography , computer science , materials science , physics , telecommunications , programming language
In semiconductor device manufacturing, optical overlay metrology measures pattern placement between two layers in a chip with sub-nm precision. Continuous improvements in overlay metrology are needed to keep up with shrinking device dimensions in modern chips. We present first overlay metrology results using a novel off-axis dark-field digital holographic microscopy concept that acquires multiple holograms in parallel by angular multiplexing. We show that this concept reduces the impact of source intensity fluctuations on the noise in the measured overlay. With our setup we achieved an overlay reproducibility of 0.13 nm and measurements on overlay targets with known programmed overlay values showed good linearity of R 2 = 0.9993. Our data show potential for significant improvement and that digital holographic microscopy is a promising technique for future overlay metrology tools.