Non-monotonic material contrast in scanning ion and scanning electron images

Abstract We demonstrate the implications of very low voltage operation (<1 kV) of a scanning electron microscope for imaging low-dimensional nanostructures where standard voltages (2–5 kV) involve a beam penetration depth comparable to the cross-section of the nanostructures. In this common situation, image sharpness, contrast quality and resolution are severely limited by emission of secondary electrons far from the primary beam incidence point. Oppositely, very low voltage operation allows reducing the beam-specimen interaction to an extremely narrow and shallow region around the incidence point, enabling high-resolution and ultra-shallow topographic contrast imaging by high-angle backscattered electrons detection on the one hand, and depth-tunable material contrast imaging by low-angle backscattered electrons detection on the other. We describe the performance of these imaging approaches on silicon nanowires obtained by the vapor-liquid-solid mechanism. Our experimental results, supported by Monte Carlo simulations of backscattered electrons emission from the nanowires, reveal the self-assembly of gold-silica core-shell nanostructures at the nanowire tips without any ad-hoc thermal oxidation step. This result demonstrates the capacity of very low voltage operation to provide optimum sharpness, contrast and resolution in low-dimensional nanostructures and to gather information about nanoscaled core-shell conformations otherwise impossible to obtain by standard scanning electron microscopy alone.

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Resolution Limits of Secondary Electron Dopant Contrast in Helium Ion and Scanning Electron Microscopy

Microscopy and Microanalysis ◽

10.1017/s1431927611000365 ◽

2011 ◽

Vol 17 (4) ◽

pp. 637-642 ◽

Cited By ~ 9

Author(s):

Mark Jepson ◽

Xiong Liu ◽

David Bell ◽

David Ferranti ◽

Beverley Inkson ◽

...

Keyword(s):

Secondary Electron ◽

Electrical Potential ◽

Helium Ion ◽

Resolution Limits ◽

Contrast Mechanism ◽

Material Contrast ◽

Dopant Atoms ◽

Scanning Electron

AbstractAs the miniaturization of semiconductor devices continues, characterization of dopant distribution within the structures becomes increasingly challenging. One potential solution is the use of the secondary electron signal produced in scanning electron (SEMs) or helium ion microscopes (HeIMs) to image the changes in electrical potential caused by the dopant atoms. In this article, the contrast mechanisms and resolution limits of secondary electron dopant contrast are explored. It is shown that the resolution of the technique is dependent on the extent of electrical potential present at a junction and that the resolution of dopant contrast can be improved in the HeIM after an in-situ plasma cleaning routine, which causes an oxide to form on the surface altering the contrast mechanism from electrical potential to material contrast.

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Approaches to Quantitative Electron Detection in the Scanning Electron Microscope for Topographic Studies

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100180604 ◽

1990 ◽

Vol 48 (1) ◽

pp. 370-371

Author(s):

Jan Hejna

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

Surface Relief ◽

Primary Beam ◽

Dimensional Metrology ◽

Backscattered Electrons ◽

Dimensional Measurements ◽

Backscattered Electron ◽

Material Contrast ◽

Scanning Electron

An electron signal in the scanning electron microscope (SEM) usually consists of contributions caused by different contrast mechanisms. The most common in practice are material and topographic contrasts. Quantification of material contrast is rather a simple matter. A backscattered electron detector placed over a specimen gives mainly material contrast which can be quantified by the use of a multichannel analyser like in the energy-dispersive x-ray spectrometry.In case of topographic contrast two problems arise. One of them is dimensional metrology, especially linewidth measurements in microelectronics, the second is reconstruction of a surface relief. The first problem needs detection conditions at which the results of SEM measurements correspond exactly with real dimensions, the second needs a signal which is related with a known formula to a local surface inclination and a procedure for converting the signal into the surface relief.Experiments in the SEM and Monte-Carlo calculations have shown that results of dimensional measurements depend on an energy of a primary beam, on a type of detected electrons (secondary electrons (SE) or backscattered electrons (BSE)) and on a type of a detector.The use of low primary beam voltages and BSE is advisable, The problem of a poor efficiency of BSE detectors at low primary beam voltages can be overcome by accelerating BSE, after they have passed through a grid rejecting SE, by high voltage applied to a scintillator in a BSE detector.

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COMPARISON OF THE EFFICIENCY OF DIFFERENT DETECTORS OF THE SCANNING ELECTRONIC MICROSCOPE «MIRA-LMH» FOR STUDYING MICROSTRUCTURE OF NANOMATERIALS

Physical and Chemical Aspects of the Study of Clusters Nanostructures and Nanomaterials ◽

10.26456/pcascnn/2021.13.250 ◽

2021 ◽

pp. 250-262

Author(s):

Дмитрий Сергеевич Кулешов ◽

Андрей Владимирович Блинов ◽

Анастасия Александровна Блинова ◽

Мария Анатольевна Ясная ◽

Давид Гурамиевич Маглакелидзе ◽

...

Keyword(s):

Secondary Electron ◽

Zinc Acetate Dihydrate ◽

Sol Gel ◽

High Sensitivity ◽

Stöber Method ◽

Electron Detector ◽

Material Contrast ◽

The Stöber Method ◽

Working Distance ◽

Scanning Electron

На первом этапе были синтезированы объекты исследования - диоксид кремния методом Штобера, где в качестве прекурсора использовали тетраэтоксисилан, и нанокомпозит ZnO - Au золь-гель методом с использованием в качестве прекурсора 2 - водного ацетата цинка. На втором этапе, микроструктуру и морфологию полученных образцов исследовали методом растровой электронной микроскопии на сканирующем электронном микроскопе «MIRA-LMH» фирмы «Tescan» с применением как классического детектора вторичных электронов, так и дополнительных детекторов - внутрилинзового детектора вторичных электронов и детектора отраженных электронов. В результате исследований установлено, что при использовании детектора вторичных электронов получаются изображения с топографическим контрастом и практически без шумов. При использовании внутрилинзового детектора вторичных электронов создаются изображения только материального контраста, без влияния рельефа поверхности. Также использование данного детектора позволило получить высококачественные изображения с большим разрешением на расстоянии от образца 5 мм. При использовании детектора отраженных электронов с рабочим расстоянием до образца 8 мм и увеличении разрешающей способности микроскопа, полученные изображения имеют низкий контраст границ, но представляют композиционную информацию с высокой чувствительностью. Таким образом, установлено, что внутрилинзовый детектор вторичных электронов, с рабочим расстоянием до образца 5 мм, является оптимальным для получения четких изображений микроструктры поверхности наноматериалов при многократном увеличении. At the first stage, the objects of study were synthesized - silicon dioxide by the Stober method, where tetraethoxysilane was used as a precursor, and a nanocomposite ZnO - Au by the sol-gel method using the aqueous zinc acetate dihydrate as a precursor. At the second stage, the microstructure and morphology of the obtained samples were investigated by scanning electron microscopy on a «MIRA-LMH» scanning electron microscope (Tescan company) using both a classical secondary electron detector and additional detectors - intralens secondary electron detector and back-scattered electrons detector. As a result of the research, it was found that when using the secondary electron detector, practically no noise images with topographic contrast are obtained. When using the intralens secondary electron detector, images of only material contrast are created, without the influence of the surface relief. Also, the use of this detector made it possible to obtain high-quality images with a high resolution at a distance of 5 mm from the sample. When using a back-scattered electrons detector with a working distance to the sample of 8 mm and increasing the resolution of the microscope, the resulting images have low border contrast, but represent compositional information with high sensitivity. Thus, it was found that the intralens secondary electron detector with a working distance of 5 mm to the sample is optimal for obtaining clear images of the microstructure of the surface of nanomaterials at multiple magnifications.

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Material Contrast of Scanning Electron and Ion Microscope Images of Metals

Microscopy Today ◽

10.1017/s1551929500054250 ◽

2008 ◽

Vol 16 (1) ◽

pp. 6-11 ◽

Cited By ~ 2

Author(s):

T. Suzuki ◽

M. Kudo ◽

Y. Sakai ◽

T. Ichinokawa

Keyword(s):

Focused Ion Beam ◽

Ion Beam ◽

Semiconductor Industry ◽

Ion Source ◽

Transmission Electron ◽

Material Contrast ◽

Ion Microscopy ◽

Ion Impact ◽

Object Of Study ◽

Scanning Electron

The rapid technical development of FIM (Focused Ion Beam) technology has spawned an increase in spatial resolution capability in scanning ion microscopy (SIM) technology. Furthermore, FIM has been used for preparation of thin specimens in transmission electron microscopy and micro-fabrication of electronic devices in the semiconductor industry. Recently, a scanning ion microscope with a helium field ion source has been developed. Thus, the contrast formation of emission electron images in scanning ion microscopy has been the object of study for analyzing images of materials specimens, similar to the theory behind scanning electron microscope (SEM) contrast formation. Furthermore, whether the electron emission yield γ induced by ion impact is periodic or non-periodic as a function of Z2 (the atomic number of the target) has not been well studied in the low energy region from several keV to the several tens of keV values used in SIM.

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Fracture Analysis of High-Strength Screw for Highway Construction

Materials ◽

10.3390/ma14071599 ◽

2021 ◽

Vol 14 (7) ◽

pp. 1599

Author(s):

Andrej Dubec ◽

Petra Kováčiková ◽

Jan Krmela ◽

Vladimíra Krmelová ◽

Artem Artyukhov

Keyword(s):

Electron Microscopy ◽

Heat Treatment ◽

Scanning Electron Microscopy ◽

Fracture Surface ◽

Central Area ◽

High Strength ◽

Material Contrast ◽

The One ◽

The Given ◽

Scanning Electron

High-strength screws represent one of the main joining or fastening components which are commonly used in the process of installation of frame constructions for information boards or signposts, relating to the traffic roads. The control of the production process may not always be a sufficient method for ensuring road safety. The backward investigation and control of the screw material processing seems to be the one of the most important procedures when there is the occurrence of any failure during the operation of the screw. This paper is mainly focused on the analysis of the failure of the high-strength screw of 10.9 grade with M diameter of 27 × 3 and a shank length of 64 mm. The mentioned and investigated screw was used as a fastener in a highway frame construction. In the paper, there is mainly the analysis of the material for a broken screw in terms of the material micropurity, the material microstructure, the surface treatment as well as chemical composition. The evaluation was based on investigation by optical microscopy, scanning electron microscopy and energy dispersive spectroscopy. Important knowledge and results were also obtained due to information on micromorphology and material contrast of the fracture surface resulting from fractographic analysis, using the method of scanning electron microscopy. In the case of the production of the high-strength screws, the tempering stands for the decisive or crucial process of heat treatment because the given process can ensure a decrease in hardness, while the required ductile properties of the material are kept and this is also reflected in the increase of strength and micromorphology of the fracture surface. From the aspect of micropurity, inclusions of critical size or distribution were not identified in the material, referring to Czech standard ČSN ISO 4967 (420471). The microstructure corresponds to tempered martensite, but the fracture surface of the broken screw was based on an intercrystalline micromechanism, which is undesirable for the given type of component. Combined with the measurement of the HV1 (Vickers hardness at a load of 1 kg) from the edge to the central area of the screw, the analysis revealed the significant drawbacks in the heat treatment of the high-strength screw.

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Pathogenesis of Human Hair Defects

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010005007x ◽

1974 ◽

Vol 32 ◽

pp. 12-13

Author(s):

P.S. Porter ◽

T. Aoyagi ◽

R. Matta

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Human Hair ◽

Standard Techniques ◽

Scanning Electron

Using standard techniques of scanning electron microscopy (SEM), over 1000 human hair defects have been studied. In several of the defects, the pathogenesis of the abnormality has been clarified using these techniques. It is the purpose of this paper to present several distinct morphologic abnormalities of hair and to discuss their pathogenesis as elucidated through techniques of scanning electron microscopy.

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Morphology, Distribution and Identification of Micro-Constituents Along Grain Boundaries in Nickel-Base Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071326 ◽

1973 ◽

Vol 31 ◽

pp. 176-177

Author(s):

D. E. Fornwalt ◽

A. R. Geary ◽

B. H. Kear

Keyword(s):

Electron Microscope ◽

Grain Boundaries ◽

Volume Fraction ◽

Rupture Life ◽

Stress Rupture ◽

High Volume ◽

Precipitate Morphology ◽

Stress Rupture Life ◽

Nickel Base ◽

Scanning Electron

A systematic study has been made of the effects of various heat treatments on the microstructures of several experimental high volume fraction γ’ precipitation hardened nickel-base alloys, after doping with ∼2 w/o Hf so as to improve the stress rupture life and ductility. The most significant microstructural chan§e brought about by prolonged aging at temperatures in the range 1600°-1900°F was the decoration of grain boundaries with precipitate particles.Precipitation along the grain boundaries was first detected by optical microscopy, but it was necessary to use the scanning electron microscope to reveal the details of the precipitate morphology. Figure 1(a) shows the grain boundary precipitates in relief, after partial dissolution of the surrounding γ + γ’ matrix.

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