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An extension of Fourier scatterometry is presented, aiming at increasing the sensitivity by measuring the phase difference between the reflections polarized parallel and perpendicular to the plane of incidence. The ellipsometric approach requires no additional hardware elements compared with conventional Fourier scatterometry. Furthermore, incoherent illumination is also sufficient, which enables spectroscopy using standard low-cost light sources.
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... This configuration, in combination with simulations, results in determining the geometrical properties of nanostructures with resolutions as high as 3 nm and over large areas. This approach distinguishes itself from other works in the literature on Fourier scatterometry, in which the phase difference properties are investigated using a focused beam spot [11][12][13]. ...
... This technique is based on Fourier microscopy and quantifies the intensity and the angle of diffracted orders that are generated by illuminating a grating at well-defined angles of incidence. Unlike other Fourier scatterometry methods described in literature, which use a focused beam spot, this technique uses a collimated laser beam (405 nm) that illuminates the nanostructures (inspection diameter 100 µm) through an objective lens (achromat, numerical aperture (NA) 0.8, working distance 0.3 µm) [11][12][13]19]. This collimated illumination is realized by focusing the incident laser beam in the back-focal plane of the objective lens. ...
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Substrate Conformal Imprint Lithography (SCIL) technology enables the fabrication of complex nanostructures with sub-10 nm resolution over large areas for industrial-scale production. This technology utilizes novel composite silicone rubber stamps that provides versatility in addition to high precision. To inspect the quality and reproducibility of the nanostructures that are fabricated using SCIL, a novel optical characterization method using Fourier microscopy is proposed. In this method, nanostructures are illuminated under a microscope objective using a collimated light beam at different incident angles and the properties of the reflected and/or diffracted beams are analysed to extract critical dimensions of the nanostructures. This fast and non-destructive method has the potentials of being used as an in-line inspection technology to extract the critical dimensions of the nanostructures over large areas and improve the overall properties of nanostructured surfaces.
... Improved sensitivity has been demonstrated by utilizing a scanning focused spot, 32-38 interferometry 39, 40 or ellipsometry. 23 ...
... 48 The sensitivity of the parameters can be checked by uncertainty analysis. 23,32,49 In case of spectroscopy and characterization of material properties, the parameterization of the dielectric function is a major issue from which a lot of technologically important material properties can be obtained, like for the case of polycrystalline semiconductors. 50, 51 Also in scatterometry, using different wavelengths in a broad range can increase the accuracy, reliability and the number of fit parameters. ...
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Indirect optical methods like ellipsometry or scatterometry require an optical model to calculate the response of the system, and to fit the parameters in order to minimize the difference between the calculated and measured values. The most common problem of optical modeling is that the measured structures and materials turn out to be more complex in reality than the simplified optical models used as first attempts to fit the measurement. The complexity of the optical models can be increased by introducing additional parameters, if they (1) are physically relevant, (2) improve the fit quality, (3) don't correlate with other parameters. The sensitivity of the parameters can be determined by mathematical analysis, but the accuracy has to be validated by reference methods. In this work some modeling and verification aspects of ellipsometry and optical scatterometry will be discussed and shown for a range of materials (semiconductors, dielectrics, composite materials), structures (damage and porosity profiles, gratings and other photonic structures, surface roughness) and cross-checking methods (atomic force microscopy, electron microscopy, x-ray diffraction, ion beam analysis). The high-sensitivity, high-throughput, in situ or in line capabilities of the optical methods will be demonstrated by different applications.
... In addition, optical scatterometry is mostly suitable for measuring repetitive dense structures, but infeasible for the measurement of isolated or generally non-periodic structures. To address the challenges or limitations in conventional optical scatterometry, several designs have been presented with the idea of trying to collect the scattering information about the nanostructure under test conditions as much as possible, such as with the goniometric optical scatter instrument [12][13][14], through-focus scanning optical microscopy [15], scatterfield microscopy [16], tomographic diffractive microscopy [17,18], and Fourier scatterometry [19,20]. Recently, we have also developed a novel instrument called the tomographic Mueller-matrix scatterometer (TMS) [21]. ...
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... Using high numerical aperture (NA) lenses, the range of incident and reflected angles can be as large as -64° to 64° using e.g. of a lens of NA = 0.9 with azimuth angles between 0° and 360°. The sensitivity can be increased by extending the instrumentations utilizing phase information by applying a scanning focused spot [7,8], by interferometry or by adding polarization information using ellipsometry [11,12]. ...
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