Effect of line-width roughness on optical scatterometry measurements

Bergner, Brent C.; Germer, Thomas A.; Suleski, Thomas J.

doi:10.1117/12.813770

Cited by 12 publications

(7 citation statements)

References 17 publications

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“…[34,35] A rough order of magnitude estimates of the effects of pattern roughness on scatterometry signals may be drawn to extract the errors in optical scatterometry measurements [36]; The other sources of uncertainty, as spot size, spectral bandwidth around the chosen wavelengths, experimental noise of the ellipsometric measures, are of same order of magnitude of 0.1% or less, depending on the used ellipsometer. [33] The ellipsometer noise may be assessed and reduced with several ellipsometric measurements for signal over noise ratio lowering, or take into account for uncertainty standard deviation assessment.…”

Section: Uncertaintymentioning

confidence: 99%

S-Genius, a universal software platform with versatile inverse problem resolution for scatterometry

et al. 2013

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S-Genius is a new universal scatterometry platform, which gathers all the LTM-CNRS know-how regarding the rigorous electromagnetic computation and several inverse problem solver solutions. This software platform is built to be a userfriendly, light, swift, accurate, user-oriented scatterometry tool, compatible with any ellipsometric measurements to fit and any types of pattern. It aims to combine a set of inverse problem solver capabilities -via adapted LevenbergMarquard optimization, Kriging, Neural Network solutions -that greatly improve the reliability and the velocity of the solution determination. Furthermore, as the model solution is mainly vulnerable to materials optical properties, S-Genius may be coupled with an innovative material refractive indices determination. This paper will a little bit more focuses on the modified Levenberg-Marquardt optimization, one of the indirect method solver built up in parallel with the total SGenius software coding by yours truly. This modified Levenberg-Marquardt optimization corresponds to a Newton algorithm with an adapted damping parameter regarding the definition domains of the optimized parameters. Currently, S-Genius is technically ready for scientific collaboration, python-powered, multi-platform (windows/linux/macOS), multi-core, ready for 2D-(infinite features along the direction perpendicular to the incident plane), conical, and 3D-features computation, compatible with all kinds of input data from any possible ellipsometers (angle or wavelength resolved) or reflectometers, and widely used in our laboratory for resist trimming studies, etching features characterization (such as complex stack) or nano-imprint lithography measurements for instance. The work about kriging solver, neural network solver and material refractive indices determination is done (or about to) by other LTM members and about to be integrated on S-Genius platform.

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Section: Uncertaintymentioning

confidence: 99%

S-Genius, a universal software platform with versatile inverse problem resolution for scatterometry

et al. 2013

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“…Previous theoretical studies of the sensitivity of angularly-resolved ellipsometry to LER were performed on large sets of 2D gratings with randomly generated LER. It has been shown that randomly generated LER can be used as a heuristic tool to evaluate its impact on angle-resolved ellipsometric data [3,4]. Nevertheless, case studies with real samples and measurements are needed in order to confirm the theoretical results.…”

Section: Introductionmentioning

confidence: 99%

Mueller matrix ellipsometry of artificial non-periodic line edge roughness in presence of finite numerical aperture

Germer¹,

Bergner

2011

SPIE Proceedings

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International audienceWe used azimuthally-resolved spectroscopic Mueller matrix ellipsometry to study a periodic silicon line structure with and without artificially-generated line edge roughness (LER). The unperturbed, reference grating profile was determined from multiple azimuthal configurations using a generalized ellipsometer, focusing the incident beam into a 60 μm spot. We used rigorous numerical modeling, taking into account the finite numerical aperture, introducing significant depolarization effects, and determining the profile shape using a four trapezoid model for the line profile. Data obtained from the artificially perturbed grating were then fit using the same model, and the resulting root-mean-square error (RMSE) values for both targets were compared. The comparison shows an increase in RMSE values for the perturbed grating that can be attributed to the effects of LER

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“…This phenomenon is called conical diffraction. 8 The MM measurement does not provide additional information about an isotropic sample or for an optical or structural anisotropic sample with symmetry in planar diffraction mode, when compared to the standard ellipsometry. This statement presumes that the sample has no features (roughness) or optical properties that result in significant depolarized scattering.…”

Section: (B)mentioning

confidence: 99%

Sensitivity analysis and line edge roughness determination of 28-nm pitch silicon fins using Mueller matrix spectroscopic ellipsometry-based optical critical dimension metrology

Dixit

O’Mullane

Sunkoju

et al. 2015

J. Micro/Nanolith. MEMS MOEMS

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Abstract. Measurement and control of line edge roughness (LER) is one of the most challenging issues facing patterning technology. As the critical dimensions (CDs) of patterned structures decrease, an LER of only a few nanometers negatively impacts device performance. Here, Mueller matrix (MM) spectroscopic ellipsometrybased scatterometry is used to characterize LER in periodic line-space structures in 28-nm pitch Si fin samples fabricated by directed self-assembly patterning. The optical response of the MM elements is influenced by structural parameters like pitch, CDs, height, and side-wall angle, as well as the optical properties of the materials. Evaluation and decoupling MM element response to LER from other structural parameters requires sensitivity analysis using scatterometry models that include LER. Here, an approach is developed that can be used to characterize LER in Si fins by comparing the optical responses generated by systematically varying the grating shape and measurement conditions. Finally, the validity of this approach is established by comparing the results obtained from power spectral density analysis of top down scanning electron microscope images and crosssectional transmission electron microscope image of the 28-nm pitch Si fins. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Effect of line-width roughness on optical scatterometry measurements

Cited by 12 publications

References 17 publications

S-Genius, a universal software platform with versatile inverse problem resolution for scatterometry

S-Genius, a universal software platform with versatile inverse problem resolution for scatterometry

Mueller matrix ellipsometry of artificial non-periodic line edge roughness in presence of finite numerical aperture

Sensitivity analysis and line edge roughness determination of 28-nm pitch silicon fins using Mueller matrix spectroscopic ellipsometry-based optical critical dimension metrology

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