Reconstruction of sub-wavelength features and nano-positioning of gratings using coherent Fourier scatterometry

Kumar, Nitish; Petrik, P.; Ramanandan, Gopika K. P.; Gawhary, Omar El; Roy, S.; Pereira, Silvania F.; Coene, W.; Urbach, H. P.

doi:10.1364/oe.22.024678

Cited by 53 publications

(46 citation statements)

References 28 publications

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“…It is the same as for coherent Fourier scatterometry experiments [4,7,12]. The light is focused by an MO to the sample.…”

Section: Principle Of Detectionmentioning

confidence: 99%

“…In case of scanning spot Fourier scatterometry [4,6,7,12,13] and interferometric Fourier scatterometry [8,14] the phase is measured between the reflected orders and with regard to a reference beam, respectively, whereas ellipsometric Fourier scatterometry measures the phase between the reflections of perpendicular polarizations. Figure 2 shows the absolute values (left graph) and phases (right graph) of the complex reflection coefficient ratios for TE and TM polarizations (equivalent with tan(Ψ) and ∆ in Eq.…”

Section: Principle Of Detectionmentioning

confidence: 99%

“…It has been shown in previous studies that involving the phase information in the measurement increases the sensitivity significantly [4], [6]- [8], [12]- [14]. The main methods investigated so far are summarized in Table 1.…”

Section: Comparisonmentioning

confidence: 99%

“…Optical scatterometry is used in numerous configurations [1]- [4] from monochromatic to spectroscopic, from reflectometric to polarimetric, from specular to angle resolved, from coherent to incoherent. In Fourier scatterometry, a focused spot is created by a high numerical aperture (NA) microscope objective (MO), and the scattered illumination is collected by the same MO [5].…”

Section: Introductionmentioning

confidence: 99%

“…By using coherent illumination and a scanning focused spot, the phase can be modulated and the phase difference between the overlapping orders can be determined [4,6,7], resulting in an increase in the sensitivity as compared to phase-insensitive incoherent Fourier scatterometry. A further advantage of the coherent illumination is that the size of the focused spot is much smaller (below one micron in the visible wavelength range).…”

Section: Introductionmentioning

confidence: 99%

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Fourier ellipsometry – an ellipsometric approach to Fourier scatterometry

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et al. 2015

J. Eur. Opt. Soc.-Rapid Publ.

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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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“…It is the same as for coherent Fourier scatterometry experiments [4,7,12]. The light is focused by an MO to the sample.…”

Section: Principle Of Detectionmentioning

confidence: 99%

Section: Principle Of Detectionmentioning

confidence: 99%

Section: Comparisonmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Fourier ellipsometry – an ellipsometric approach to Fourier scatterometry

Petrik

Kumar

Fried

et al. 2015

J. Eur. Opt. Soc.-Rapid Publ.

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Bayesian Target‐Vector Optimization for Efficient Parameter Reconstruction

Plock

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Burger

et al. 2022

Advcd Theory and Sims

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Parameter reconstructions are indispensable in metrology. Here, the objective is to explain K experimental measurements by fitting to them a parameterized model of the measurement process. The model parameters are regularly determined by least-square methods, that is, by minimizing the sum of the squared residuals between the K model predictions and the K experimental observations, 𝝌 2 . The model functions often involve computationally demanding numerical simulations. Bayesian optimization methods are specifically suited for minimizing expensive model functions. However, in contrast to least-square methods such as the Levenberg-Marquardt algorithm, they only take the value of 𝝌 2 into account, and neglect the K individual model outputs. A Bayesian target-vector optimization scheme with improved performance over previous developments, that considers all K contributions of the model function and that is specifically suited for parameter reconstruction problems which are often based on hundreds of observations is presented. Its performance is compared to established methods for an optical metrology reconstruction problem and two synthetic least-squares problems. The proposed method outperforms established optimization methods. It also enables to determine accurate uncertainty estimates with very few observations of the actual model function by using Markov chain Monte Carlo sampling on a trained surrogate model.

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In Situ Characterization of Biomaterials at Solid‐Liquid Interfaces Using Ellipsometry in the UV‐Visible‐NIR Wavelength Range

Kalas

Agócs

Romanenko

et al. 2019

Physica Status Solidi (a)

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Understanding interface processes has been gaining crucial importance in many applications of biology, chemistry, and physics. The boundaries of those disciplines had been quickly vanishing in the last decade, as metrologies and the knowledge gained based on their use improved and increased rapidly. Optical techniques such as microscopy, waveguide sensing, or ellipsometry are significant and widely used means of studying solid‐liquid interfaces because the applicability of ions, electrons, or X‐ray radiation is strongly limited for this purpose due to the high absorption in aqueous ambient. Light does not only provide access to the interface making the measurement possible, but utilizing the phase information and the large amount of spectroscopic data, the ellipsometric characterization is also highly sensitive and robust. This article focuses on ellipsometry of biomaterials in the visible wavelength range. The authors discuss the main challenges of measuring thickness and optical properties of ultra‐thin films such as biomolecules. The authors give an overview on different kinds of flow cells from conventional through internal reflection to combined methods. They emphasize that surface nanostructures and evaluation strategies are also crucial parts of in situ bioellipsometry and summarize some of the recent trends showing examples mainly from their research.

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Reconstruction of sub-wavelength features and nano-positioning of gratings using coherent Fourier scatterometry

Cited by 53 publications

References 28 publications

Fourier ellipsometry – an ellipsometric approach to Fourier scatterometry

Fourier ellipsometry – an ellipsometric approach to Fourier scatterometry

Bayesian Target‐Vector Optimization for Efficient Parameter Reconstruction

In Situ Characterization of Biomaterials at Solid‐Liquid Interfaces Using Ellipsometry in the UV‐Visible‐NIR Wavelength Range

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