Nanoscale grating characterization through EUV spectroscopy aided by machine learning techniques

Bahrenberg, Lukas; Glabisch, Sven; Danylyuk, Serhiy; Ghafoori, Moein; Schröder, Sophia; Brose, Sascha; Stollenwerk, Jochen; Loosen, Peter

doi:10.1117/12.2550508

Cited by 3 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this work, EUV spectrometry is applied and evaluated to investigate nanoscale gratings with dedicated LER and LWR properties. EUV spectrometry measures the broadband reflectance of the sample under investigation for various grazing incidence angles, which corresponds to measuring the zeroth diffraction order efficiency of a grating like sample 8,9 . Based on the reflectance data, several surface related geometrical features as well as sub-surface cross-sectional information and material specification can be reconstructed in a model-based approach with up to sub-nanometer accuracy in terms of averaged properties of the sample 8,9 .…”

Section: Euv Spectrometrymentioning

confidence: 99%

“…EUV spectrometry measures the broadband reflectance of the sample under investigation for various grazing incidence angles, which corresponds to measuring the zeroth diffraction order efficiency of a grating like sample 8,9 . Based on the reflectance data, several surface related geometrical features as well as sub-surface cross-sectional information and material specification can be reconstructed in a model-based approach with up to sub-nanometer accuracy in terms of averaged properties of the sample 8,9 . Besides of grating like samples, the utilized technique is suitable for the reconstruction of thin layer systems and its capability for the determination of optical constants 10 with an absolute uncertainty below 0.001 has been demonstrated 10 .…”

Section: Euv Spectrometrymentioning

confidence: 99%

“…To measure the spectral and angular resolved reflectance of the samples, the compact EUV spectrometer, developed at the Chair for Technology of Optical Systems, RWTH Aachen University (RWTH-TOS) 8,9,10 , shown in Figure 1 & Figure 2 is utilized which main components are the radiation source, two sequential spectrographs and the sample positioning system. Due to the strong absorption of EUV radiation, the whole setup is operated under vacuum conditions, reaching pressures below 5•10 -6 mbar at the sample position.…”

Section: Euv Spectrometrymentioning

confidence: 99%

“…Due to the strong absorption of EUV radiation, the whole setup is operated under vacuum conditions, reaching pressures below 5•10 -6 mbar at the sample position. A discharge-produced plasma (DPP) EUV source emits unpolarized broadband EUV radiation from a hot and dense xenon plasma with high intensity in a spectral range from 10.7 nm -15.5 nm 8 and with reduced intensity up to 20 nm. The beam is spatially filtered by an aperture and the non-EUV part of the spectrum is spectrally filtered out by a 200 nm thick zirconium thin film filter before the beam is directed to a first diffraction grating that is illuminated in classical configuration (beam perpendicular to grating lines).…”

Section: Euv Spectrometrymentioning

confidence: 99%

See 3 more Smart Citations

Investigation of stochastic roughness effects for nanoscale grating characterization with a stand-alone EUV spectrometer

Glabisch

Schröder

Brose

et al. 2022

Photomask Technology 2022

View full text Add to dashboard Cite

Fast and non-destructive non-imaging metrology of nanostructures is crucial for the development of integrated circuits and for the corresponding in-situ metrology within fabrication processes. Stochastic variations related to the gratings local period (line edge roughness, LER) and line width (line width roughness, LWR) are of special interest due to their key role for the minimal achievable structure size. Non-imaging metrology approaches taking these statistic variations into account are quite limited. For scatterometry, models predict a change of the grating’s diffraction efficiency according to a DebyeWaller factor but only in the non-zeroth diffraction orders. The authors perform simulations of nanoscale gratings that suggest an influence of LER and LWR on the reflectance (zeroth diffraction order efficiency) which motivate an extended study on LER and LWR measured by spectrally resolved EUV reflectometry here described as EUV spectrometry. The authors present reconstruction results of nanoscale gratings measured with a compact spectrometer utilizing extreme ultraviolet (EUV) radiation emitted by a discharged-produced plasma (DPP) EUV source. The use of two sequential spectrographs, one for the reference measurement of the source spectrum, the other one for the measurement of the spectrum after sample interaction, combined within the experimental setup allows to measure the broadband reflectance with 2% relative uncertainty of samples under various grazing incidence angles. The method offers a proven sub-nm reconstruction accuracy for critical grating parameters. Within the presented study, the measured samples are dedicated test samples, fabricated to exhibit well-defined LER and LWR at different grating periods and linewidths. In addition, the samples are also cross-characterized by the Physikalisch-Technische Bundesanstalt (PTB, Berlin). Experimental and simulative results are discussed to derive approaches to include LER and LWR as parameters in the physical model for reconstruction.

show abstract

Section: Euv Spectrometrymentioning

confidence: 99%

Section: Euv Spectrometrymentioning

confidence: 99%

Section: Euv Spectrometrymentioning

confidence: 99%

Section: Euv Spectrometrymentioning

confidence: 99%

See 2 more Smart Citations

Investigation of stochastic roughness effects for nanoscale grating characterization with a stand-alone EUV spectrometer

Glabisch

Schröder

Brose

et al. 2022

Photomask Technology 2022

View full text Add to dashboard Cite

show abstract

Nanoscale grating characterization using EUV scatterometry and soft x-ray scattering with plasma and synchrotron radiation

Lohr¹,

Ciesielski²,

Glabisch

et al. 2022

Appl. Opt.

View full text Add to dashboard Cite

Modern semiconductor structures reach sizes in the nanometer regime. Optical metrology characterizes test structures for the quality assessment of semiconductor fabrication. The limits of radiation to resolve nanometer structure sizes can be overcome by shortening the wavelength. The compact source extreme ultraviolet (EUV) scatterometer presented here characterizes samples in the EUV spectral range using plasma radiation. Reference measurements with synchrotron radiation are carried out using a beamline scatterometer. A comparison including Markov chain Monte Carlo sampling shows that the compact source and beamline setups can both determine the given dimensional parameters of a nanoscale grating with uncertainties in the sub-nanometer range. Grating characterization based on soft x ray scattering has increased accuracy.

show abstract

Characterization of nanoscale gratings by spectroscopic reflectometry in the extreme ultraviolet with a stand-alone setup

et al. 2020

View full text Add to dashboard Cite

The authors present a study on the dimensional characterization of nanoscale line gratings by spectroscopic reflectometry in the extreme ultraviolet spectral range (5 nm to 20 nm wavelength). The investigated grating parameters include the line height, the line width, the sidewall angle and corner radii. The study demonstrates that the utilization of shorter wavelengths in state-of-the-art optical scatterometry provides a high sensitivity with respect to the geometrical dimensions of nanoscale gratings. Measurable contrasts are demonstrated for dimensional variations in the sub-percent regime, down to one tenth of a nanometer and one tenth of a degree in absolute terms. In an experimental validation of the method, it is shown that reflectance curves can be obtained in a stand-alone setup using the broadband emission of a discharge produced plasma as the source of EUV radiation, demonstrating the potential scalability of the method for industrial uses. Simulated reflectance curves are fit to the experimental curves by variation of the grating parameters using rigorous electromagnetic modeling. The obtained grating parameters are cross-checked by a scanning electron microscopy analysis.

show abstract

Nanoscale grating characterization through EUV spectroscopy aided by machine learning techniques

Cited by 3 publications

References 0 publications

Investigation of stochastic roughness effects for nanoscale grating characterization with a stand-alone EUV spectrometer

Investigation of stochastic roughness effects for nanoscale grating characterization with a stand-alone EUV spectrometer

Nanoscale grating characterization using EUV scatterometry and soft x-ray scattering with plasma and synchrotron radiation

Characterization of nanoscale gratings by spectroscopic reflectometry in the extreme ultraviolet with a stand-alone setup

Contact Info

Product

Resources

About