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Pleshkov R, Chkhalo N, Polkovnikov V, Svechnikov M, Zorina M. Intrinsic roughness and interfaces of Cr/Be multilayers. J Appl Crystallogr 2021. [DOI: 10.1107/s160057672101027x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The structures of Cr/Be multilayer mirror interfaces are investigated using X-ray reflectometry, diffuse X-ray scattering and atomic force microscopy. The combination of these methods makes it possible to separate the contributions of roughness and interlayer diffusion/intermixing for each sample. In the range of period thicknesses of 2.26–0.8 nm, it is found that the growth roughness of the Cr/Be multilayer mirrors does not depend on the period thickness and is ∼0.2 nm. The separation of roughness and diffuseness allows estimation of layer material intermixing and the resulting drop in the optical contrast, which is from 0.85 to 0.17 in comparison with an ideally sharp structure.
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Herrero AF, Pflüger M, Puls J, Scholze F, Soltwisch V. Uncertainties in the reconstruction of nanostructures in EUV scatterometry and grazing incidence small-angle X-ray scattering. OPTICS EXPRESS 2021; 29:35580-35591. [PMID: 34808989 DOI: 10.1364/oe.430416] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 07/01/2021] [Indexed: 06/13/2023]
Abstract
Increasing miniaturization and complexity of nanostructures require innovative metrology solutions with high throughput that can assess complex 3D structures in a non-destructive manner. EUV scatterometry is investigated for the characterization of nanostructured surfaces and compared to grazing-incidence small-angle X-ray scattering (GISAXS). The reconstruction is based on a rigorous simulation using a Maxwell solver based on finite-elements and is statistically validated with a Markov-Chain-Monte-Carlo sampling method. It is shown that in comparison to GISAXS, EUV allows to probe smaller areas and to reduce the computation times obtaining comparable uncertainties.
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Shape- and Element-Sensitive Reconstruction of Periodic Nanostructures with Grazing Incidence X-ray Fluorescence Analysis and Machine Learning. NANOMATERIALS 2021; 11:nano11071647. [PMID: 34201579 PMCID: PMC8306736 DOI: 10.3390/nano11071647] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/10/2021] [Accepted: 06/17/2021] [Indexed: 11/24/2022]
Abstract
The characterization of nanostructured surfaces with sensitivity in the sub-nm range is of high importance for the development of current and next-generation integrated electronic circuits. Modern transistor architectures for, e.g., FinFETs are realized by lithographic fabrication of complex, well-ordered nanostructures. Recently, a novel characterization technique based on X-ray fluorescence measurements in grazing incidence geometry was proposed for such applications. This technique uses the X-ray standing wave field, arising from an interference between incident and the reflected radiation, as a nanoscale sensor for the dimensional and compositional parameters of the nanostructure. The element sensitivity of the X-ray fluorescence technique allows for a reconstruction of the spatial element distribution using a finite element method. Due to a high computational time, intelligent optimization methods employing machine learning algorithms are essential for timely provision of results. Here, a sampling of the probability distributions by Bayesian optimization is not only fast, but it also provides an initial estimate of the parameter uncertainties and sensitivities. The high sensitivity of the method requires a precise knowledge of the material parameters in the modeling of the dimensional shape provided that some physical properties of the material are known or determined beforehand. The unknown optical constants were extracted from an unstructured but otherwise identical layer system by means of soft X-ray reflectometry. The spatial distribution profiles of the different elements contained in the grating structure were compared to scanning electron and atomic force microscopy and the influence of carbon surface contamination on the modeling results were discussed. This novel approach enables the element sensitive and destruction-free characterization of nanostructures made of silicon nitride and silicon oxide with sub-nm resolution.
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Makhotkin IA, Wu M, Soltwisch V, Scholze F, Philipsen V. Refined extreme ultraviolet mask stack model. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2021; 38:498-503. [PMID: 33798178 DOI: 10.1364/josaa.416235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 02/09/2021] [Indexed: 06/12/2023]
Abstract
A refined model of an extreme ultraviolet (EUV) mask stack consisting of the Mo/Si multilayer coated by a Ru protective layer and a TaBN/TaBO absorber layer was developed to facilitate accurate simulations of EUV mask performance for high-NA EUV photo-lithography (EUVL) imaging. The model is derived by combined analysis of the measured EUV and x ray reflectivity of an industry-representative mask blank. These two sets of measurements were analyzed using a combined free-form analysis procedure that delivers high-resolution x ray and EUV optical constant depth profiles based on self-adapted sets of sublayers as thin as 0.25 nm providing a more accurate description of the reflectivity than obtained from only EUV reflectivity. "Free-form analysis" means that the shape of the layer interfaces in the model is determined experimentally and is not given a priori by the structure model. To reduce the numerical effort for EUV imaging simulations, a low-resolution model of the multilayer and absorber stack with sublayer thicknesses larger than 2 nm, that fits to only the EUV reflectance, was derived from the high-resolution model. Rigorous high-NA EUVL simulations were done to compare the performance of the new model to our previous work [Proc. SPIE8886, 88860B (2013)PSISDG0277-786X10.1117/12.2030663].
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Yurakov YA, Peshkov YA, Ivkov SA, Kannykin SV, Sitnikov AV, Domashevskaya EP. The state of individual layers and interfaces in multilayer nanostructures [(
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46. SURF INTERFACE ANAL 2020. [DOI: 10.1002/sia.6908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Yury A. Yurakov
- Department of Solid State Physics and Nanostructures Voronezh State University Voronezh Russia
| | - Yaroslav A. Peshkov
- Department of Solid State Physics and Nanostructures Voronezh State University Voronezh Russia
| | - Sergey A. Ivkov
- Department of Solid State Physics and Nanostructures Voronezh State University Voronezh Russia
| | - Sergey V. Kannykin
- Department of Solid State Physics and Nanostructures Voronezh State University Voronezh Russia
| | - Alexander V. Sitnikov
- Department of Solid State Physics Voronezh State Technical University Voronezh Russia
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Svechnikov M. Multifitting: software for the reflectometric reconstruction of multilayer nanofilms. J Appl Crystallogr 2020. [DOI: 10.1107/s160057671901584x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Multifitting is a computer program designed specifically for modeling the optical properties (reflection, transmission, absorption) of multilayer films consisting of an arbitrary number of layers in a wide range of wavelengths. Multifitting allows a user to calculate the reflectometric curves for a given structure (direct problem) and to find the parameters of the films from the experimentally obtained curves (inverse problem), either manually or automatically. Key features of Multifitting are the ability to work simultaneously with an arbitrary number of experimental curves and an ergonomic graphical user interface that is designed for intensive daily use in the diagnosis of thin films. Multifitting is positioned by the author as the successor to the IMD program, which has become the standard tool in research and technology groups synthesizing and studying thin-film coatings.
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Feng J, Huang Q, Qi R, Xu X, Zhou H, Huo T, Giglia A, Yang X, Wang H, Zhang Z, Wang Z. Stability of Cr/C multilayer during synchrotron radiation exposure and thermal annealing. OPTICS EXPRESS 2019; 27:38493-38508. [PMID: 31878615 DOI: 10.1364/oe.27.038493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Accepted: 12/02/2019] [Indexed: 06/10/2023]
Abstract
The stability of Cr/C multilayer during irradiation or thermal annealing was investigated using grazing incidence X-ray reflectivity measurement, X-ray photoelectron spectroscopy, X-ray diffraction analysis, small-angle X-ray scattering analysis, and soft X-ray reflectivity measurement. One sample was irradiated with a white beam of synchrotron radiation and five other samples were annealed at various temperatures. The 18-h irradiation treatment caused local surface contaminants but did not affect the buried stacks. The annealing treatment resulted in increased reflectivity at approximately 1.2 keV, and the multilayer remained stable for temperature up to 700 °C. Thus, the Cr/C multilayers exhibited excellent stability during irradiation and thermal treatments and can be used for the mirrors and multilayer gratings of third-generation synchrotron radiation systems.
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Chandrasekaran A, van de Kruijs RWE, Sturm JM, Zameshin AA, Bijkerk F. Nanoscale Transition Metal Thin Films: Growth Characteristics and Scaling Law for Interlayer Formation. ACS APPLIED MATERIALS & INTERFACES 2019; 11:46311-46326. [PMID: 31729860 PMCID: PMC6909253 DOI: 10.1021/acsami.9b14414] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 11/15/2019] [Indexed: 06/10/2023]
Abstract
A comprehensive study on the growth of nanoscale transition metal-on-transition metal (TM-on-TM) systems is presented. The near room-temperature intermixing and segregation phenomena during growth are studied in vacuo using high-sensitivity low-energy ion scattering. The investigated TM-on-TM systems are classified into four types according to the observed intermixing and segregation behavior. Empirical rules are suggested to qualitatively predict the growth characteristics of any TM-on-TM system based on the atomic size difference, surface-energy difference, and enthalpy of mixing between the film and substrate atoms. An exponential trend is observed in the effective interface width as a function of the surface-energy difference between the film and substrate layers, with a subtrend based on the crystal structure of the TM layers. A semiempirical model that accurately describes the experimental data is presented. It serves as a scaling law to predict the effective interface width and the minimum film thickness required for full film coverage in TM-on-TM systems in general. The ability to predict the growth characteristics as well as the interface width for any TM-on-TM system significantly contributes to the process of finding the best material combination for a specific application, where layer growth characteristics are implicitly considered when selecting materials based on their functional properties.
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Jiang H, Wang H, Zhu J, Xue C, Zhang J, Tian N, Li A. Thickness-dependent structural characteristics for a sputtering-deposited chromium monolayer and Cr/C and Cr/Sc multilayers. JOURNAL OF SYNCHROTRON RADIATION 2018; 25:785-792. [PMID: 29714189 DOI: 10.1107/s1600577518005143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 03/30/2018] [Indexed: 06/08/2023]
Abstract
The interior structure, morphology and ligand surrounding of a sputtering-deposited chromium monolayer and Cr/C and Cr/Sc multilayers are determined by various hard X-ray techniques in order to reveal the growth characteristics of Cr-based thin films. A Cr monolayer presents a three-stage growth mode with sudden changes occurring at a layer thickness of ∼2 nm and beyond 6 nm. Cr-based multilayers are proven to have denser structures due to interfacial diffusion and layer growth mode. Cr/C and Cr/Sc multilayers have different interfacial widths resulting from asymmetry, degree of crystallinity and thermal stability. Cr/Sc multilayers present similar ligand surroundings to Cr foil, whereas Cr/C multilayers are similar to Cr monolayers. The aim of this study is to help understand the structural evolution regulation versus layer thickness and to improve the deposition technology of Cr-based thin films, in particular for obtaining stable Cr-based multilayers with ultra-short periods.
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Affiliation(s)
- Hui Jiang
- Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 239 Zhangheng Road, Pudong District, Shanghai 201204, People's Republic of China
| | - Hua Wang
- Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 239 Zhangheng Road, Pudong District, Shanghai 201204, People's Republic of China
| | - Jingtao Zhu
- MOE Key Laboratory of Advanced Micro-Structured Materials, School of Physics Science and Engineering, Tongji University, Shanghai 200092, People's Republic of China
| | - Chaofan Xue
- Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 239 Zhangheng Road, Pudong District, Shanghai 201204, People's Republic of China
| | - Jiayi Zhang
- MOE Key Laboratory of Advanced Micro-Structured Materials, School of Physics Science and Engineering, Tongji University, Shanghai 200092, People's Republic of China
| | - Naxi Tian
- Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 239 Zhangheng Road, Pudong District, Shanghai 201204, People's Republic of China
| | - Aiguo Li
- Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 239 Zhangheng Road, Pudong District, Shanghai 201204, People's Republic of China
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Soltwisch V, Hönicke P, Kayser Y, Eilbracht J, Probst J, Scholze F, Beckhoff B. Element sensitive reconstruction of nanostructured surfaces with finite elements and grazing incidence soft X-ray fluorescence. NANOSCALE 2018; 10:6177-6185. [PMID: 29561052 DOI: 10.1039/c8nr00328a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The geometry of a Si3N4 lamellar grating was investigated experimentally with reference-free grazing-incidence X-ray fluorescence analysis. While simple layered systems are usually treated with the matrix formalism to determine the X-ray standing-wave field, this approach fails for laterally structured surfaces. Maxwell solvers based on finite elements are often used to model electrical field strengths for any 2D or 3D structures in the optical spectral range. We show that this approach can also be applied in the field of X-rays. The electrical field distribution obtained with the Maxwell solver can subsequently be used to calculate the fluorescence intensities in full analogy to the X-ray standing-wave field obtained by the matrix formalism. Only the effective 1D integration for the layer system has to be replaced by a 2D integration of the finite elements, taking into account the local excitation conditions. We will show that this approach is capable of reconstructing the geometric line shape of a structured surface with high elemental sensitivity. This combination of GIXRF and finite-element simulations paves the way for a versatile characterization of nanoscale-structured surfaces.
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Affiliation(s)
- Victor Soltwisch
- Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin, Germany.
| | - Philipp Hönicke
- Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin, Germany.
| | - Yves Kayser
- Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin, Germany.
| | - Janis Eilbracht
- Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin, Germany.
| | - Jürgen Probst
- Helmholtz-Zentrum Berlin (HZB), Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - Frank Scholze
- Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin, Germany.
| | - Burkhard Beckhoff
- Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin, Germany.
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Makhotkin IA, Sobierajski R, Chalupský J, Tiedtke K, de Vries G, Störmer M, Scholze F, Siewert F, van de Kruijs RWE, Milov I, Louis E, Jacyna I, Jurek M, Klinger D, Nittler L, Syryanyy Y, Juha L, Hájková V, Vozda V, Burian T, Saksl K, Faatz B, Keitel B, Plönjes E, Schreiber S, Toleikis S, Loch R, Hermann M, Strobel S, Nienhuys HK, Gwalt G, Mey T, Enkisch H. Experimental study of EUV mirror radiation damage resistance under long-term free-electron laser exposures below the single-shot damage threshold. JOURNAL OF SYNCHROTRON RADIATION 2018; 25:77-84. [PMID: 29271755 PMCID: PMC5741122 DOI: 10.1107/s1600577517017362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Accepted: 12/04/2017] [Indexed: 06/07/2023]
Abstract
The durability of grazing- and normal-incidence optical coatings has been experimentally assessed under free-electron laser irradiation at various numbers of pulses up to 16 million shots and various fluence levels below 10% of the single-shot damage threshold. The experiment was performed at FLASH, the Free-electron LASer in Hamburg, using 13.5 nm extreme UV (EUV) radiation with 100 fs pulse duration. Polycrystalline ruthenium and amorphous carbon 50 nm thin films on silicon substrates were tested at total external reflection angles of 20° and 10° grazing incidence, respectively. Mo/Si periodical multilayer structures were tested in the Bragg reflection condition at 16° off-normal angle of incidence. The exposed areas were analysed post-mortem using differential contrast visible light microscopy, EUV reflectivity mapping and scanning X-ray photoelectron spectroscopy. The analysis revealed that Ru and Mo/Si coatings exposed to the highest dose and fluence level show a few per cent drop in their EUV reflectivity, which is explained by EUV-induced oxidation of the surface.
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Affiliation(s)
- Igor A. Makhotkin
- Industrial Focus Group XUV Optics, MESA+ Institute for Nanotechnology, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands
| | - Ryszard Sobierajski
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, PL-02-668 Warsaw, Poland
| | - Jaromir Chalupský
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - Kai Tiedtke
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, Hamburg 22607, Germany
| | - Gosse de Vries
- ASML Netherlands BV, PO Box 324, Veldhoven, 5500 AH, The Netherlands
| | - Michael Störmer
- Helmholtz-Zentrum Geesthacht, Max-Planck-Strasse 1, Geesthacht 21502, Germany
| | - Frank Scholze
- Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, Berlin 10587, Germany
| | - Frank Siewert
- Helmholtz Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, Berlin 12489, Germany
| | - Robbert W. E. van de Kruijs
- Industrial Focus Group XUV Optics, MESA+ Institute for Nanotechnology, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands
| | - Igor Milov
- Industrial Focus Group XUV Optics, MESA+ Institute for Nanotechnology, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands
| | - Eric Louis
- Industrial Focus Group XUV Optics, MESA+ Institute for Nanotechnology, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands
| | - Iwanna Jacyna
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, PL-02-668 Warsaw, Poland
| | - Marek Jurek
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, PL-02-668 Warsaw, Poland
| | - Dorota Klinger
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, PL-02-668 Warsaw, Poland
| | - Laurent Nittler
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, PL-02-668 Warsaw, Poland
| | - Yevgen Syryanyy
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, PL-02-668 Warsaw, Poland
| | - Libor Juha
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
- Institute of Plasma Physics, Academy of Sciences of the Czech Republic, Za Slovankou 3, 182 00 Prague 8, Czech Republic
| | - Věra Hájková
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
| | - Vojtěch Vozda
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
- MFF, Institute of Physics of Charles University, Ke Karlovu 5, Prague 2, Czech Republic
| | - Tomáš Burian
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
- Institute of Plasma Physics, Academy of Sciences of the Czech Republic, Za Slovankou 3, 182 00 Prague 8, Czech Republic
| | - Karel Saksl
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
- Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, Košice 040 01, Slovak Republic
| | - Bart Faatz
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, Hamburg 22607, Germany
| | - Barbara Keitel
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, Hamburg 22607, Germany
| | - Elke Plönjes
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, Hamburg 22607, Germany
| | - Siegfried Schreiber
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, Hamburg 22607, Germany
| | - Sven Toleikis
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, Hamburg 22607, Germany
| | - Rolf Loch
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, Hamburg 22607, Germany
| | - Martin Hermann
- Carl Zeiss SMT GmbH, Rudolf-Eber-Strasse 2, Oberkochen 73447, Germany
| | - Sebastian Strobel
- Carl Zeiss SMT GmbH, Rudolf-Eber-Strasse 2, Oberkochen 73447, Germany
| | | | - Grzegorz Gwalt
- Helmholtz Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, Berlin 12489, Germany
| | - Tobias Mey
- Laser-Laboratorium Göttingen eV, Hans-Adolf-Krebs-Weg 1, Göttingen 37077, Germany
| | - Hartmut Enkisch
- Carl Zeiss SMT GmbH, Rudolf-Eber-Strasse 2, Oberkochen 73447, Germany
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Fernández Herrero A, Pflüger M, Probst J, Scholze F, Soltwisch V. Characteristic diffuse scattering from distinct line roughnesses. J Appl Crystallogr 2017. [DOI: 10.1107/s1600576717014455] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Lamellar gratings are widely used diffractive optical elements; gratings etched into Si can be used as structural elements or prototypes of structural elements in integrated electronic circuits. For the control of the lithographic manufacturing process, a rapid in-line characterization of nanostructures is indispensable. Numerous studies on the determination of regular geometry parameters of lamellar gratings from optical and extreme ultraviolet (EUV) scattering highlight the impact of roughness on the optical performance as well as on the reconstruction of these structures. Thus, a set of nine lamellar Si gratings with a well defined line edge roughness or line width roughness were designed. The investigation of these structures using EUV small-angle scattering reveals a strong correlation between the type of line roughness and the angular scattering distribution. These distinct scattering patterns open new paths for the unequivocal characterization of such structures by EUV scatterometry.
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Huang Q, Yi Q, Cao Z, Qi R, Loch RA, Jonnard P, Wu M, Giglia A, Li W, Louis E, Bijkerk F, Zhang Z, Wang Z. High Reflectance Nanoscale V/Sc Multilayer for Soft X-ray Water Window Region. Sci Rep 2017; 7:12929. [PMID: 29018232 PMCID: PMC5635135 DOI: 10.1038/s41598-017-13222-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 09/20/2017] [Indexed: 11/13/2022] Open
Abstract
V/Sc multilayer is experimentally demonstrated for the first time as a high reflectance mirror for the soft X-ray water window region. It primarily works at above the Sc-L edge (λ = 3.11 nm) under near normal incidence while a second peak appears at above the V-L edge (λ = 2.42 nm) under grazing incidence. The V/Sc multilayer fabricated with a d-spacing of 1.59 nm and 30 bilayers has a smaller interface width (σ = 0.27 and 0.32 nm) than the conventional used Cr/Sc (σ = 0.28 and 0.47 nm). For V/Sc multilayer with 30 bilayers, the introduction of B4C barrier layers has little improvement on the interface structure. As the number of bilayers increasing to 400, the growth morphology and microstructure of the V/Sc layers evolves with slightly increased crystallization. Nevertheless, the surface roughness remains to be 0.25 nm. A maximum soft X-ray reflectance of 18.4% is measured at λ = 3.129 nm at 9° off-normal incidence using the 400-bilayers V/Sc multilayer. According to the fitted model, an s-polarization reflectance of 5.2% can also be expected at λ = 2.425 nm under 40° incidence. Based on the promising experimental results, further improvement of the reflectance can be achieved by using a more stable deposition system, exploring different interface engineering methods and so on.
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Affiliation(s)
- Qiushi Huang
- Key Laboratory of Advanced Micro-Structured Materials MOE, Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Qiang Yi
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621900, China
| | - Zhaodong Cao
- Shanghai Institute of Laser Plasma, China Academy of Engineering Physics, Shanghai, China
| | - Runze Qi
- Key Laboratory of Advanced Micro-Structured Materials MOE, Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Rolf A Loch
- The Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, LuruperChaussee 149, Hamburg, 22761, Germany
| | - Philippe Jonnard
- Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 Rue Pierre et Marie Curie, F-75231, Paris Cedex 05, Paris, France.,CNRS UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 Rue Pierre et Marie Curie, F-75231, Paris Cedex 05, Paris, France
| | - Meiyi Wu
- Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 Rue Pierre et Marie Curie, F-75231, Paris Cedex 05, Paris, France.,CNRS UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 Rue Pierre et Marie Curie, F-75231, Paris Cedex 05, Paris, France
| | - Angelo Giglia
- CNR Istituto Officina Materiali, 34149, Trieste, Italy
| | - Wenbin Li
- Key Laboratory of Advanced Micro-Structured Materials MOE, Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Eric Louis
- Industrial Focus Group XUV Optics, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - Fred Bijkerk
- Industrial Focus Group XUV Optics, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
| | - Zhong Zhang
- Key Laboratory of Advanced Micro-Structured Materials MOE, Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Zhanshan Wang
- Key Laboratory of Advanced Micro-Structured Materials MOE, Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China.
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Svechnikov M, Pariev D, Nechay A, Salashchenko N, Chkhalo N, Vainer Y, Gaman D. Extended model for the reconstruction of periodic multilayers from extreme ultraviolet and X-ray reflectivity data. J Appl Crystallogr 2017. [DOI: 10.1107/s1600576717012286] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
An extended model for the reconstruction of multilayer nanostructures from reflectometry data in the X-ray and extreme ultraviolet ranges is proposed. In contrast to the standard model approach, where the transitional region is defined in advance as a specific function, the transition layer is sought as a linear combination of several functions at once in the extended model. This allows one to describe a much wider class of multilayer structures with different dominant physical mechanisms for the formation of transition regions. The extended model occupies an intermediate position between the classical model approach and the so-called model-free methods. The efficiency of the described method is illustrated in detail in numerical simulations and in a real experiment on the annealing of a multilayer Mo/Be mirror.
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Ghafoor N, Eriksson F, Aquila A, Gullikson E, Schäfers F, Greczynski G, Birch J. Impact of B 4C co-sputtering on structure and optical performance of Cr/Sc multilayer X-ray mirrors. OPTICS EXPRESS 2017; 25:18274-18287. [PMID: 28789315 DOI: 10.1364/oe.25.018274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 07/13/2017] [Indexed: 06/07/2023]
Abstract
The influence of B4C incorporation during magnetron sputter deposition of Cr/Sc multilayers intended for soft X-ray reflective optics is investigated. Chemical analysis suggests formation of metal: boride and carbide bonds which stabilize an amorphous layer structure, resulting in smoother interfaces and an increased reflectivity. A near-normal incidence reflectivity of 11.7%, corresponding to a 67% increase, is achieved at λ = 3.11 nm upon adding 23 at.% (B + C). The advantage is significant for the multilayer periods larger than 1.8 nm, where amorphization results in smaller interface widths, for example, giving 36% reflectance and 99.89% degree of polarization near Brewster angle for a multilayer polarizer. The modulated ion-energy-assistance during the growth is considered vital to avoid intermixing during the interface formation even when B + C are added.
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Haase A, Soltwisch V, Braun S, Laubis C, Scholze F. Interface morphology of Mo/Si multilayer systems with varying Mo layer thickness studied by EUV diffuse scattering. OPTICS EXPRESS 2017; 25:15441-15455. [PMID: 28788969 DOI: 10.1364/oe.25.015441] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 05/16/2017] [Indexed: 06/07/2023]
Abstract
We investigate the influence of the Mo-layer thickness on the EUV reflectance of Mo/Si mirrors with a set of unpolished and interface-polished Mo/Si/C multilayer mirrors. The Mo-layer thickness is varied in the range from 1.7 nm to 3.05 nm. We use a novel combination of specular and diffuse intensity measurements to determine the interface roughness throughout the multilayer stack and do not rely on scanning probe measurements at the surface only. The combination of EUV and X-ray reflectivity measurements and near-normal incidence EUV diffuse scattering allows to reconstruct the Mo layer thicknesses and to determine the interface roughness power spectral density. The data analysis is conducted by applying a matrix method for the specular reflection and the distorted-wave Born approximation for diffuse scattering. We introduce the Markov-chain Monte Carlo method into the field in order to determine the respective confidence intervals for all reconstructed parameters. We unambiguously detect a threshold thickness for Mo in both sample sets where the specular reflectance goes through a local minimum correlated with a distinct increase in diffuse scatter. We attribute that to the known appearance of an amorphous-to-crystallization transition at a certain thickness threshold which is altered in our sample system by the polishing.
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