Query: sem backscatter vs. secondary electron

Candidate papers:

abstract: Critical dimension measurements for state of the art sub micron semiconductor processes are typically accomplished using automated scanning electron microscopes. The measurements generated in these instruments are primarily based upon secondary electron imaging techniques. Several issues associated with this mode of SEM imaging that directly impact the precision and accuracy of the measurement system are reviewed. These issues have led to the current investigation of SEM metrology utilizing backscattered electron imaging techniques. The implications and differences between SE and BSE imaging techniques and their relation to CD measurements are discussed in this work.(c) (1994) COPYRIGHT SPIE The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
author_names: Neal T Sullivan

Robert Newcomb
title: Critical dimension measurement in the SEM: comparison of backscattered vs. secondary electron detection
year: 1994

abstract: Abstract In a scanning electron microscope (SEM) an electron beam sets up an omni directional source of scattered electrons within a specimen. Diffraction of these electrons will occur simultaneously on all lattice planes in the sample and the backscattered electrons (BSE) which escape from the specimen, will form a diffraction pattern that can be imaged on a phosphor screen. This is the basis of electron backscatter diffraction (EBSD) Similar diffraction effects cause individual grains of different orientations to give different total BSE. SEM images that exploit this effect will show orientation contrast (OC) EBSD and OC imaging are SEM based crystallographic tools. EBSD enables measurement of the crystallographic orientation of individual rock forming minerals as small as 1 mm, and the calculation of misorientation axes and angles between any two data points. OC images enable mapping of all misorientation boundaries in a specimen and thus provide a location map for EBSD analyses. EBSD coupled to OC imaging in the SEM enables complete specimen microtextures and mesotextures to be determined. EBSD and OC imaging can be applied to any mineral at a range of scales and enable us to expand the microstructural approach, so successful in studies of quartz rocks, for example, to the full range of rock forming minerals. Automated EBSD analysis of rocks remains problematic, although continuing technical developments are enabling progress in this area. EBSD and OC are important new tools for petrologists and petrographers. Present and future applications of EBSD and OC imaging include phase identification, studying deformation mechanisms, constraining dislocation slip systems, empirical quantification of microstructures, studying metamorphic processes, studying magmatic processes, and constraining geochemical microsampling. In all these cases, quantitative crystallographic orientation data enable more rigorous testing of models to explain observed microstructures.
author_names: David J Prior

Alan P Boyle

Frank E Brenker

Michael C Cheadle

Austin Day

Gloria Lopez

Luca Peruzzo

Graham J Potts

Steve Reddy

Richard Spiess

Nicholas E Timms

Patrick Trimby

John Wheeler

Lena Zetterstrom
title: The application of electron backscatter diffraction and orientation contrast imaging in the SEM to textural problems in rocks
year: 1999

abstract: The so called "total yield" approach often fails to explain the measured sign of the surface potential, VS, and the shift of the nominal critical energy EC2 (where ddeg+edeg=1) of electron irradiated insulators. Here, a simple modification of this approach consists in including some extra interactions of the secondary and backscattered electrons with the electron traps generated previously by the irradiation itself. The trends in the evolution of the total yield, d+e, and of VS as a function of the irradiation time (from their initial values up to their steady values) are then deduced for a wide primary beam energy range (1 50 keV) and for different external collector (or specimen holder) bias. New mechanisms are suggested for the contrasts observed in insulators investigated in scanning electron microscopy (SEM) The present analysis applies for a wide variety of electron beam techniques (SEM, Auger electron spectroscopy, and electron probe microanalysis) operated on a wide variety of insulating specimens a.
author_names: Jacques Cazaux
title: Some considerations on the secondary electron emission, d, from e irradiated insulators
year: 1999

abstract: Creep cavitation in an ex service nuclear steam header Type 316 stainless steel sample is investigated through a multiscale tomography workflow spanning eight orders of magnitude, combining X ray computed tomography (CT) plasma focused ion beam (FIB) scanning electron microscope (SEM) imaging and scanning transmission electron microscope (STEM) tomography. Guided by microscale X ray CT, nanoscale X ray CT is used to investigate the size and morphology of cavities at a triple point of grain boundaries. In order to understand the factors affecting the extent of cavitation, the orientation and crystallographic misorientation of each boundary is characterised using electron backscatter diffraction (EBSD) Additionally, in order to better understand boundary phase growth, the chemistry of a single boundary and its associated secondary phase precipitates is probed through STEM energy dispersive X ray (EDX) tomography. The difference in cavitation of the three grain boundaries investigated suggests that the orientation of grain boundaries with respect to the direction of principal stress is important in the promotion of cavity formation.
author_names: Thomas J A Slater

Robert S Bradley

Giacomo Bertali

Remco Geurts

S M Northover

Michael G Burke

Sarah J Haigh

Timothy L Burnett

Philip J Withers
title: Multiscale correlative tomography: an investigation of creep cavitation in 316 stainless steel
venue: Scientific Reports
year: 2017

abstract: For studying the electrical properties (charge trapping, transport and secondary electron emission) of the polypropylene based nanocomposites with different contents of natural clay, the specimens were submitted to electron irradiation of a scanning electron microscope. A device, suitably mounted on the sample holder of the scanning electron microscope, was used to measure two currents (i.e. leakage and displacement currents) induced in the polypropylene based nanocomposites (polymer nanocomposites) under electron irradiation. The evolution of trapped charge during irradiation for each type of studied polymer nanocomposites is deduced. The amount of trapped charge at the steady state is also determined by measuring the change of secondary electron image size associated to the electron trajectory simulation. It is found, surprisingly, that not only the leakage current increases as a function of clay loading level but also trapped charge. However, this could be related to the increase of conductivity in one hand and to proliferation of interfaces between nanoparticles and neighbouring materials on the other hand. These two processes play crucial role in controlling the carrier transport (through polymer nanocomposites or/and along its surface) closely related to the charge storage and leakage current.
author_names: Latifa Ben Ammar

Slim Fakhfakh

Omar Jbara

Sebastien Rondot
title: Effect of nanoclay concentration level on the electrical properties of polypropylene under electron irradiation in a SEM
venue: Journal of microscopy
year: 2017

abstract: This paper presents a characterization study of specimens manufactured from Ti 6Al 4V powder with the use of laser engineered net shaping technology (LENS) Two different orientations of the specimens were considered to analyze the loading direction influence on the material mechanical properties. Moreover, two sets of specimens, as built (without heat treatment) and after heat treatment, were used. An optical measurement system was also adopted for determining deformation of the specimen, areas of minimum and the maximum principal strain, and an effective plastic strain value at failure. The loading direction dependence on the material properties was observed with a significant influence of the orientation on the stress and strain level. Microstructure characterization was examined with the use of optical and scanning electron microscopes (SEM) in addition, the electron backscatter diffraction (EBSD) was also used. The fracture mechanism was discussed based on the fractography analysis. The presented comprehensive methodology proved to be effective and it could be implemented for different materials in additive technologies. The material data was used to obtain parameters for the selected constitutive model to simulate the energy absorbing structures manufactured with LENS technology. Therefore, a brief discussion related to numerical modelling of the LENS Ti 6Al 4V alloy was also included in the paper. The numerical modelling confirmed the correctness of the acquired material data resulting in a reasonable reproduction of the material behavior during the cellular structure deformation process.
author_names: Aleksandra Szafranska

Anna Antolak-Dudka

Pawel Baranowski

Pawel Bogusz

Dariusz Zasada

Jerzy Malachowski

Tomasz Czujko
title: Identification of Mechanical Properties for Titanium Alloy Ti 6Al 4V Produced Using LENS Technology
venue: Materials
year: 2019

abstract: Austenitisation is one of the most important factors in heat treatment process of dual phase high carbon steel, as it can affect the grain size, production of secondary phase precipitation, size of martensite laths and distribution of the phases. Despite the importance of this heat treatment on mechanical behaviour, its correlation on corrosion behaviour and electrochemical properties of high carbon steel required in depth investigation. The aim of this study is to investigate the effect of different austenitising temperatures on microstructure and corrosion behaviour of dual phase high carbon steel. Microstructural evolution was observed in situ using ultra high temperature laser microscope, and the steels have been characterised further using optical microscope, electron backscatter diffraction, 3D laser scanning confocal microscope, scanning electron microscope and energy energy dispersive spectroscope and electron probe microanalysis. The powerful electrochemical corrosion test was employed by using Tafel polarisation method to measure its corrosion rate. Results have indicated that higher austenitising temperature increased grain size of retained austenite and martensite, which reduced the grain boundary length, but at the same time increased the size and amount of carbide precipitations. As the main corrosion mechanisms in dual phase high carbon steel were pitting corrosion and intergranular corrosion, effect of generated precipitations has overcome grain boundary corrosion caused by influence of size and shape of microstructures and, thus, reduced the corrosion resistance around 9.68% as temperature increased. These findings are crucial for designing new applications from high carbon steels for mining and automotive industries.
author_names: Wilson Handoko

Farshid Pahlevani

Veena Sahajwalla
title: Effect of austenitisation temperature on corrosion resistance properties of dual phase high carbon steel
venue: Journal of Materials Science
year: 2019

abstract: Focused ion beam (FIB) milling has enabled the development of key microstructure characterization techniques (e.g. 3D electron backscatter diffraction (EBSD) 3D scanning electron microscopy imaging, site specific sample preparation for transmission electron microscopy, site specific atom probe tomography) and micro mechanical testing techniques (e.g. micro pillar compression, micro beam bending, in situ TEM nanoindentation) Yet, in most milling conditions, some degree of FIB damage is introduced via material redeposition, Ga+ ion implantation or another mechanism. The level of damage and its influence vary strongly with milling conditions and materials characteristics, and cannot always be minimized. Here, a masking technique is introduced, that employs standard FIB SEM equipment to protect specific surfaces from redeposition and ion implantation. To investigate the efficiency of this technique, high angular resolution EBSD (HR EBSD) has been used to monitor the quality of the top surface of several micro pillars, as they were created by milling a ringcore hole in a stress free silicon wafer, with or without protection due to an "umbrella" HR EBSD provides a high sensitivity estimation of the amount of FIB damage on the surface. Without the umbrella, EBSD patterns are severely influenced, especially within 5 um of the milled region. With an optimized umbrella, sharp diffraction patterns are obtained near the hole, as revealed by average cross correlation factors greater than 0.9 and equivalent phantom strains of the order 2 x 10 4. Thus, the umbrella method is an efficient and versatile tool to support a variety of FIB based techniques.
author_names: Tijmen Vermeij

Emeric Plancher

Cemal Cem Tasan
title: Preventing damage and redeposition during focused ion beam milling: The "umbrella" method.
venue: Ultramicroscopy
year: 2018

abstract: The interaction of ionizing radiation with matter is of critical importance in numerous areas of science and technology like space and vacuum technology and even medicine and biotechnology. Secondary electron emission is a consequence of electron irradiation on materials. We achieve extremely low secondary electron emission yield values smaller than 0.2, even up to incident electron energies ~1 keV, due to an undocumented synergy between neighbouring metal and dielectric domains in composite samples. To investigate this experimental discovery, we propose a simple 3D model where the dielectric and metallic domains are arranged in parallel and interleaved. The proposed surface profile has a triangular shape to model the surface roughness. We obtain a continuous equation to describe the electric field that arises between grounded conductors and charged dielectrics domains. The calculated trajectories of secondary electrons in this 3D geometry are used to predict dynamic secondary emission yield, which strongly depends on the charge accumulated in the dielectric domains. This research paves the way to design new materials of low secondary emission yield, addressing the technological problem not yet resolved to inhibit the electron avalanche in RF equipment that limit their maximum working power.
author_names: Leandro Olano

Maria E Davila

J R Dennison

Petronilo Martin-Iglesias

Isabel Montero
title: Dynamic secondary electron emission in rough composite materials
venue: Scientific Reports
year: 2019

abstract: This paper presents a high signal to noise ratio electron energy spectrometer attachment for the scanning electron microscope (SEM) designed to measure changes in specimen surface potential from secondary electrons and extract specimen atomic number information from backscattered electrons. Experimental results are presented, which demonstrate that the spectrometer can in principle detect specimen voltage changes well into the sub mV range, and distinguish close atomic numbers by a signal to noise ratio of better than 20. The spectrometer has applications for quantitatively mapping specimen surface voltage and atomic number variations on the nano scale.
author_names: Hung Quang Hoang

Mans Osterberg

Anjam Khursheed
title: A high signal to noise ratio toroidal electron spectrometer for the SEM.
venue: Ultramicroscopy
year: 2011