Fitting-determined formulation of effective medium approximation for 3D trench structures in model-based infrared reflectrometry

Zhang, Chuanwei; Liu, Shiyuan; Shi, Tielin; Tang, Zirong

doi:10.1364/josaa.28.000263

Cited by 11 publications

(7 citation statements)

References 28 publications

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“…As inferred from Figure b, a large fraction of the Ge film is consumed as reducing agent during Ag NHS synthesis (i.e., Galvanic displacement). Accordingly, we model the Ge layer as a porous medium and compute its dielectric function using dielectric mixing (i.e., Ge in vacuum) by zero-order effective medium approximation …”

Section: Results and Discussionmentioning

confidence: 99%

“…Accordingly, we model the Ge layer as a porous medium and compute its dielectric function using dielectric mixing (i.e., Ge in vacuum) by zero-order effective medium approximation. 25 The boundary conditions for the unit cell are employed to represent infinite repetition of NHSs in 2D. It is not a straightforward task to adopt an effective interparticle separation in our simulations.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Plasmon Resonances in Nanohemisphere Monolayers

Topal¹,

Jaradat²,

Karumuri³

et al. 2017

J. Phys. Chem. C

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Plasmonic devices, consisting of nanoparticle monolayers, are conveniently fabricated by deposition techniques, wherein thermodynamics often favor the particle shape to be close to hemispherical. The present work investigates plasmon modes in Ag nanohemispheres (NHSs) using s-and p-polarized incident radiation at varying angles. The Ag NHSs, immobilized on nanoposts, resembling mushroom structures, allow for reduced substrate coupling and convenient resolution of the modes. Additionally, the modes are studied by in situ extinction acquisitions during nanoparticle synthesis and elucidated by numerical simulations. It is revealed that the broken symmetry by asymmetric particle shape leads to dipolar modes parallel and normal to the base, which are significantly different in terms of energy, excitation dependence on polarization, and particle−particle as well as particle−substrate couplings. In particular, the major parallel mode offers distinct advantages in plasmonics applications over nanospheres. For example, its strong substrate coupling may benefit thin film photovoltaics by efficient light coupling. Higher field concentrations are induced at the sharp edges of a NHS that may enhance hot electron injection in a photocatalyst. Unlike in a spherical dimer, where the field intensity peaks in the middle of the gap, the maximum field in a NHS dimer gap occurs on the metal surface (i.e., at the edges), overlaying with the chemical enhancement. Hence, a higher surface enhancement factor can be achieved in Raman scattering.

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Section: Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Plasmon Resonances in Nanohemisphere Monolayers

Topal¹,

Jaradat²,

Karumuri³

et al. 2017

J. Phys. Chem. C

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show abstract

“…The in-house computer program used for data analysis is based on MATLABV R high-level language and interactive environment [version (R2013b), The MathWorks, Inc., Natick, MA, USA], which will be run on a 2.3 GHz Intel i5-2410M personal computer. Here, the in-house computer program mainly contains two parts, which are the forward modeling based on RCWA algorithm 8 and the inverse extraction based on least square regression 10,13 and robust estimation. 24,25…”

Section: Drc-mme In Order Of Light Propagation Is Pcr 1 Scr 2 Amentioning

confidence: 99%

“…The inherent essence of nonlinear regression is that the profile parameters are achieved through an iterative procedure, which repeatedly requires computation of the forward modeling. 13 Since the relationship between the optical signature and the profile parameters is highly nonlinear, the forward modeling procedure is usually time-consuming, and it will be even worse and unacceptable for two-dimensional or more complex nanostructure measurements. Hence, the nonlinear regression method is rarely used in the in-line monitoring of the complex nanostructure fabrications.…”

Section: Introductionmentioning

confidence: 99%

Fast and accurate solution of inverse problem in optical scatterometry using heuristic search and robust correction

Zhu

Jiang

Shi

et al. 2015

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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Library search is one of the most commonly used methods in optical scatterometry, which consists of the beforehand construction of a signature library and the grid search. The efficiency of existing search algorithms such as k-dimensional tree method and locality-sensitive hashing heavily depends on the size of the signature library and usually is inversely proportional to the library scale. Additionally, since the two-norm based objective function is quite sensitive to the outliers, the abnormally distributed measurement errors will bias the solution of the traditional chi-square or maximum likelihood function. In the present paper, the authors propose a heuristic search algorithm and a robust correction method to realize the fast library search and to achieve the more accurate results, respectively. Instead of searching in the signature library, the authors perform the search procedure in an extra constructed Jacobian library using the principle of gradient-based iteration algorithms, by which the fast search speed can be achieved for an arbitrary scale library. After the search, a robust correction procedure is performed on the basis of the searched optimal parameter set to obtain the more accurate results. Simulations and experiments performed on an etched silicon grating have demonstrated the feasibility of the proposed heuristic search algorithm and robust correction method. V

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“…There are many reliable forward-modeling techniques such as the rigorous coupled-wave analysis (RCWA), the finite element method (FEM), the boundary element method (BEM), or the finite-difference time-domain (FDTD) method. The profile 2 of 12 reconstruction process conducted under a fixed measurement configuration is an inverse problem with the objective of optimizing a set of floating profile parameters (e.g., CD, sidewall angle, and height) whose theoretical signatures can best match the measured ones through regression analysis or library search [12][13][14]. The measurement configuration is defined as a combination of specially selected wavelengths and incident and azimuthal angles.…”

Section: Introductionmentioning

confidence: 99%

Dependence-Analysis-Based Data-Refinement in Optical Scatterometry for Fast Nanostructure Reconstruction

et al. 2019

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Optical scatterometry is known as a powerful tool for nanostructure reconstruction due to its advantages of being non-contact, non-destructive, low cost, and easy to integrate. As a typical model-based method, it usually makes use of abundant measured data for structural profile reconstruction, on the other hand, too much redundant information significantly degrades the efficiency in profile reconstruction. We propose a method based on dependence analysis to identify and then eliminate the measurement configurations with redundant information. Our experiments demonstrated the capability of the proposed method in an optimized selection of a subset of measurement wavelengths that contained sufficient information for profile reconstruction and strikingly improved the profile reconstruction efficiency without sacrificing accuracy, compared with the primitive approach, by making use of the whole spectrum.

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Fitting-determined formulation of effective medium approximation for 3D trench structures in model-based infrared reflectrometry

Cited by 11 publications

References 28 publications

Plasmon Resonances in Nanohemisphere Monolayers

Plasmon Resonances in Nanohemisphere Monolayers

Fast and accurate solution of inverse problem in optical scatterometry using heuristic search and robust correction

Dependence-Analysis-Based Data-Refinement in Optical Scatterometry for Fast Nanostructure Reconstruction

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