Through-focus scanning-optical-microscope imaging method for nanoscale dimensional analysis

National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
Optics Letters (Impact Factor: 3.29). 10/2008; 33(17):1990-2. DOI: 10.1364/OL.33.001990
Source: PubMed


We present a novel optical technique that produces nanometer dimensional measurement sensitivity using a conventional bright-field optical microscope, by analyzing through-focus scanning-optical-microscope images obtained at different focus positions. In principle, this technique can be used to identify which dimension is changing between two nanosized targets and to determine the dimension using a library-matching method. This methodology has potential utility for a wide range of target geometries and application areas, including nanometrology, nanomanufacturing, semiconductor process control, and biotechnology.

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Available from: Ravikiran Attota, Sep 23, 2014
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    • "different types of dimensional variations and different magnitudes, a wide variety of target geometries can be used, and the requirement for defining the "Best Focus" is eliminated [5] [6] [7] [8] [9] [10] [11] "
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    ABSTRACT: We present a novel optical through-focus scanning optical microscopy (TSOM) method that produces nanoscale dimensional measurement sensitivity using a conventional optical microscope. The TSOM method uses optical information from multiple focal planes for dimensional analysis. The TSOM method can be used for nanoscale dimensional and defect analysis for a wide variety of target geometries and sizes. We present here an application of the method to analyze the size and shape of nanoparticles. We present the analysis based on simulations and also provide experimental data.
    Proceedings of SPIE - The International Society for Optical Engineering 03/2012; DOI:10.1117/12.918263 · 0.20 Impact Factor
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    • "This information may be obtained using an appropriate data acquisition and analysis method. Based on this, and on the observation of a distinct signature for different parametric variations, we introduced a new method for nanoscaledimensional analysis with nanometer sensitivity for threedimensional , nanosized targets using a conventional brightfield optical microscope [7] [8] [9] [10] [11] [12]. The method is referred to as the 'through-focus scanning optical microscopy' (TSOM pronounced as 'tee-som') imaging method. "
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    ABSTRACT: Through‐focus scanning optical microscopy (TSOM) is a relatively new method that transforms conventional optical microscopes into truly three‐dimensional metrology tools for nanoscale to microscale dimensional analysis. TSOM achieves this by acquiring and analyzing a set of optical images collected at various focus positions going through focus (from above‐focus to under‐focus). The measurement resolution is comparable to what is possible with typical light scatterometry, scanning electron microscopy (SEM) and atomic force microscopy (AFM). TSOM method is able to identify nanometer scale difference, type of the difference and magnitude of the difference between two nano∕micro scale targets using a conventional optical microscope with visible wavelength illumination. Numerous industries could benefit from the TSOM method—such as the semiconductor industry, MEMS, NEMS, biotechnology, nanomanufacturing, data storage, and photonics. The method is relatively simple and inexpensive, has a high throughput, provides nanoscale sensitivity for 3D measurements and could enable significant savings and yield improvements in nanometrology and nanomanufacturing. Potential applications are demonstrated using experiments and simulations.
    11/2011; 1395(1):57-63. DOI:10.1063/1.3657866
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    • "Several techniques were developed in extending the capability of optical tools to the nanoscale. For instance, Attota et al. [1] proposed a through-focus scanning-optical-microscope imaging method and verified its sensitivity in nanostructure metrology, by analyzing through-focus images obtained at different focus positions, rather than one " best-focus " image. Besides, scatterometry [2], a diffraction-based measurement where the scattering features are periodic, involves two approaches, i.e. angle scatterometry and spectroscopic scatterometry, and can satisfy many of the needs of high volume manufacturing. "
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    ABSTRACT: This paper presents the modeling and simulation of Mueller matrix polarimetry for nanostructure metrology, with an emphasis on the sensitivity analysis. Taking a two-dimensional grating as an example, the modeling method using the rigorous coupled-wave analysis theory has been described. The Mueller matrix elements are obtained with different measurement configurations, such as changing the wavelength and azimuthal angle. It is observed that different geometrical parameters show variable sensitivities even under a fixed measurement configuration, and more information is achievable by changing the configuration. It is thus verified that it is feasible and effective to characterize nanostructures by the Mueller matrix polarimetry.
    Advances in Optoelectronics and Micro/Nano-Optics (AOM), 2010 OSA-IEEE-COS; 01/2011
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