Abstract
It has been known since 1959 that the focal-plane intensity distribution produced by focusing polarized light with a high-numerical-aperture lens should be highly asymmetric1. Remarkably, the consequences of this fundamental effect in direct image acquisition have remained unexploited, although vectorial effects have been observed in the contexts of free-space focusing2, molecular fluorescence3 and photolithography4. By using extreme-numerical-aperture (values of 3.5), solid-immersion microscopy5,6,7 we have obtained images of a silicon integrated circuit showing, for the first time, the dramatic influence of polarization on their spatial resolution, with values from 100 nm to 250 nm. Our data show that polarization-sensitive imaging can substantially surpass the scalar diffraction limit embodied by classical formulae such as Sparrow's criterion. Such performance will have an impact on activities such as integrated-circuit failure analysis, where optical inspection faces serious challenges from the sub-100-nm feature sizes routinely used in production devices.
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Acknowledgements
The authors would like to acknowledge the support of the UK Engineering and Physical Sciences Research Council (EPSRC) under grant number EP/C509765/1. One of the authors (K.A.S.) acknowledges financial support from the EPSRC under a doctoral training award. The support of Credence Inc. is also gratefully acknowledged.
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K.A.S. and E.R. performed the experiments. R.J.W. and D.T.R. conceived the project. K.A.S. and D.T.R. analysed the data. All the authors contributed to the writing of the paper.
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Serrels, K., Ramsay, E., Warburton, R. et al. Nanoscale optical microscopy in the vectorial focusing regime. Nature Photon 2, 311–314 (2008). https://doi.org/10.1038/nphoton.2008.29
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DOI: https://doi.org/10.1038/nphoton.2008.29
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