We introduce a plasmonic resonance ridge aperture capable of sensing changes in refractive index and absorption with nanoscale resolution. Using this aperture, we devised a plasmonic near-field scanning nanoscope (PNSN) to record images of heterogeneous nanostructures. Compared to a conventional near-field scanning optical microscope (NSOM) that measures light scattered by the sample, the PNSN directly measures the change in a beam reflected from the aperture to detect buried objects. Using the PNSN we recorded images of nanoscale rectangular groove arrays on a SiO(2) substrate with patterns typical of a dynamic random access memory circuit. By comparing the experimental and calculated image of the nanostructure, we estimate the resolution of PNSN to be ~20 nm, which is ~50% smaller than the near-field spot generated by the aperture. Also, we theoretically analyzed the feasibility of the PNSN detecting an object underneath a metal film.

We propose a scheme of overlay alignment for plasmonic lithography using a scanning contact probe. Using two resonances of a ridge aperture in a metal film, we introduce the aperture's multifunctional characteristics for patterning and alignment at different wavelengths. To verify this idea, we measure an image of an alignment mark using a scanning ridge aperture and determine the reference point for the alignment. We then analyze the uncertainty of the alignment method with respect to the image data noise and compare the numerical results with the experimental results. The uncertainty of the overlay alignment method is shown to be less than approximately 2 nm.

Herein, we apply a plasmonic near-field scanning nanoscope using a resonant ridge aperture to measure the thickness of a metal thin film. We determine an appropriate design for the resonant ridge aperture to obtain a high dynamic range and sensitivity for the measurement. As a proof of concept, we measure the thickness of gold thin films with thicknesses ranging between 5 and 30 nm. We demonstrate that the experimental and calculated results are in good agreement with one another. Also, we find that any observed errors are caused by uncertainties in the material properties of the metal and by tolerances in the fabrication of the ridge aperture. By comparing these thickness measurements with those taken with atomic force microscopy, we are able to obtain an uncertainty of ∼5% for our thickness measurements. Regarding the spatial resolution, theoretical analysis indicates that the thickness of a metal thin film should be detectable below 40 nm. Lee, Oh, and Hahn: Thickness measurements of metal thin films with a plasmonic near-field. Downloaded From: http://nanophotonics.spiedigitallibrary.org/ on 05/15/2015 Terms of Use: http://spiedl.org/terms Lee, Oh, and Hahn: Thickness measurements of metal thin films with a plasmonic near-field. Downloaded From: http://nanophotonics.spiedigitallibrary.org/ on 05/15/2015 Terms of Use: http://spiedl.org/terms Lee, Oh, and Hahn: Thickness measurements of metal thin films with a plasmonic near-field. Downloaded From: http://nanophotonics.spiedigitallibrary.org/ on 05/15/2015 Terms of Use: http://spiedl.org/terms Lee, Oh, and Hahn: Thickness measurements of metal thin films with a plasmonic near-field. Downloaded From: http://nanophotonics.spiedigitallibrary.org/ on 05/15/2015 Terms of Use: http://spiedl.org/terms Lee, Oh, and Hahn: Thickness measurements of metal thin films with a plasmonic near-field. Downloaded From: http://nanophotonics.spiedigitallibrary.org/ on 05/15/2015 Terms of Use: http://spiedl.org/terms Lee, Oh, and Hahn: Thickness measurements of metal thin films with a plasmonic near-field. Downloaded From: http://nanophotonics.spiedigitallibrary.org/ on 05/15/2015 Terms of Use: http://spiedl.org/terms Lee, Oh, and Hahn: Thickness measurements of metal thin films with a plasmonic near-field.

ABSTRACT:In this work, we describe a scatterometer, which is devised to detect defect patterns in the molded plastic cases of mobile phones. Fourier transform is applied to the scattered image of the defect pattern to calculate the distribution of spatial frequency of the pattern. By examining the spatial frequency distribution, which meets the defect patterns, we can greatly enhance the image contrast of the defect by separating the defect and background patterns. For practical purposes, a dielectric-layer coating containing micrometer-sized TiO 2 -coated urethane balls is proposed for the molded case to reduce the visibility of defect patterns. The resulting changes in visibility are analyzed to investigate the effect of the weight ratio of the microballs in the dielectric layer. The visibility decreases by a factor of 2.7 with 5% weight ratio of the microball. C