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Environmental Scanning Electron Microscopy and its Application Possibilites in ISI ASCR
Neděla, Vilém
The first commercially available environmental scanning electron microscope (ESEM) was introduced in 1988 by Dr. G.D. Danilat and his company Electro Scan. Prof. Autrata and Doc. Jirák of the Institute of Scientific Instruments of the Academy of Science of the Czech Republic, public research institution, and the Brno University of Technology launched a laboratory operation with the first purely Czech ESEM AQUASEM in 1995. The Team of Environmental Electron Microscopy (EEM), headed by Dr. Vilém Neděla, a former student of Professor Autrata, has continued the nearly twenty-year tradition of ESEM progress in the Czech Republic. The team has studied interactions of electrons with high-pressure gas environments, designed, developed and simulated detection systems for SEM and ESEM and performed simulations of gas flows in ESEM. In interdisciplinary cooperation with various partners the team has developed and tested methods of observation of sensitive, native or live specimen studied under conditions of dynamic in-situ experiments using the today already obsolete ESEM AQUASEM II with directly heated tungsten cathode converted by Dr. Neděla at the Institute of Scientific Instruments of the Academy of Science of the Czech Republic still in his student years. In near future the institute plans purchase of a new ESEM with high resolution and a unique configuration of accessory analytical and other equipment. Thus a new laboratory of environmental electron microscopy with state-of-the-art equipment will be established at the ISI ASCR in Brno. The new laboratory will allow for specimen study with electron beam in combination with optional micro handling, dynamic in-situ experiments with specimen temperature variation from -25°C to 1000°C, or local gas and liquid injecting directly onto the sample.
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History of Electron Microscopy at the Institute of Scientific Instruments
Müllerová, Ilona
The development of the first transmission electron microscope (EM) at the Institute of Scientific Instruments (ISI) was completed in 1951. In 1954 a functional model of a desktop EM (the Tesla BS 242) was built and it won the Gold Medal at EXPO 1958. Over 1000 of these instruments were produced over a period of 20 years and exported to 20 countries. Unique transmission, emission and scanning EMs were developed and built during the 1960s. At the same time, the issues with high voltage sources, vacuum (and subsequently ultrahigh vacuum) and with the analysis of residual gases were resolved. In 1962, the first electron interference experiments in the world were carried out at ISI. Non-conventional forms of EM were also developed in the 1970s, e.g. interference shadow EM, Lorentz and tunneling EM, emission microscopy, as well as low energy electron diffraction [1]. Since 1973 the finite element method has been exploited for the computation of electrostatic and magnetic lenses. The ultrahigh vacuum scanning EM with cold field emission gun and an Auger spectrometer was fully developed and built at ISI in 1976, and the electron beam writer with a shaped beam and field emission gun in 1985. The development of new scintillation and cathodoluminescent screens began in the 1970s and our single crystal Yttrium Aluminium Garnet detector significantly improved detection systems all over the world. Low- and very-low-energy scanning EM was introduced to the world in 1990 as a unique technique. Today, it can achieve resolution as low as 4.5 nm at the incident electron energy of 20 eV.
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Main Activites of the Institute of Scientific Instruments
Müllerová, Ilona ; Radlička, Tomáš ; Mika, Filip ; Krzyžánek, Vladislav ; Neděla, Vilém ; Sobota, Jaroslav ; Zobač, Martin ; Kolařík, Vladimír ; Starčuk jr., Zenon ; Srnka, Aleš ; Jurák, Pavel ; Zemánek, Pavel ; Číp, Ondřej ; Lazar, Josef ; Mrňa, Libor
Institute of Scientific Instruments (ISI) was established in 1957 to develop diverse instrumental equipment for other institutes of the Academy of Sciences. ISI has long experience in research and development of electron microscopes, nuclear magnetic resonance equipment, coherent optics and related techniques. Nowadays the effort concentrates on scientific research in the field of methodology of physical properties of matter, in particular in the field of electron optics, electron microscopy and spectroscopy, microscopy for biomedicine, environmental electron microscopy, thin layers, electron and laser beam welding, electron beam lithography using Gaussian and shaped electron beam, nuclear magnetic resonance and spectroscopy, cryogenics and superconductivity, measurement and processing of biosignals in medicine, non-invasive cardiology, applications of focused laser beam (optical tweezers, long-range optical delivery of micro- and nano-objects) and lasers for measurement and metrology. ISI works both independently and in cooperation with universities, other research and professional institutions and with private companies at national and international level.
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Workshop of Interesting Topics of SEM and ESEM
Neděla, Vilém ; Mašová, Šárka ; Tihlaříková, Eva
The book of abstracts from the Workshop of Interesting Topics of SEM and ESEM includes original English written papers focused on new results of Environmental electron microscopy group from the ISI ASCR in Brno ant scientific and industry partners of this group. This book contain new results from the field of instrumentation, biology, physics and chemistry. The overall objectives of the workshop were to provide space for exchanging news, ideas, advice and experience in the field of Electron Microscopy which can lead to mutual future scientific collaboration. This workshop has been organized as a forum of state-of-the-art discussion in a number of topics which will be covered by several distinguished invited talks and other presentations.
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Monte-Carlo simulation of proximity effect in e-beam lithography
Urbánek, Michal ; Kolařík, Vladimír ; Krátký, Stanislav ; Matějka, Milan ; Horáček, Miroslav ; Chlumská, Jana
E–beam lithography is the most used pattern generation technique for academic and research prototyping. During this patterning by e–beam into resist layer, several effects occur which change the resolution of intended patterns. Proximity effect is the dominant one which causes that patterning areas adjacent to the beam incidence point are exposed due to electron scattering effects in solid state. This contribution deals with Monte Carlo simulation of proximity effect for various accelerating beam voltage (15 kV, 50 kV, 100 kV), typically used in e–beam writers. Proximity effect simulation were carried out in free software Casino and commercial software MCS Control Center, where each of electron trajectory can be simulated (modeled). The radial density of absorbed energy is calculated for PMMA resist with various settings of resist thickness and substrate material. At the end, coefficients of proximity effect function were calculated for beam energy of 15 keV, 50 keV and 100 keV which is desirable for proximity effect correction.
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Comparison of ultimate resolution achieved by e-beam writers with shaped beam and with Gaussian beam
Krátký, Stanislav ; Kolařík, Vladimír ; Matějka, Milan ; Urbánek, Michal ; Horáček, Miroslav ; Chlumská, Jana
This contribution deals with the comparison of two different e–beam writer systems. E–beam writer with rectangular shaped beam BS600 is the first system. This system works with electron energy of 15 keV. Vistec EBPG5000+ HR is the second system. That system uses the Gaussian beam for pattern generation and it can work with two different electrons energies of values 50 keV and 100 keV. The ultimate resolution of both systems is the main aspect of comparison. The achievable resolution was tested on patterns consisted of single lines, single dots (rectangles for e–beam writer with shaped beam) and small areas of periodic gratings. Silicon wafer was used as a substrate for resist deposition. Testing was carried out with two resists, PMMA as a standard resist for electron beam lithography, and HSQ resist as a material for ultimate resolution achievement. Process of pattern generation (exposition) is affected by the same undesirable effect (backscattering and forward scattering of electrons, proximity effect etc.). However, these effects contribute to final pattern (resolution) by various dispositions. These variations caused the different results for similar conditions (the same resist, dose, chemical developer etc.). Created patterns were measured and evaluated by using of atomic force microscope and scanning electron microscope.
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Lift-Off technique using different e-beam writers
Chlumská, Jana ; Kolařík, Vladimír ; Krátký, Stanislav ; Matějka, Milan ; Urbánek, Michal ; Horáček, Miroslav
This paper deals with lift–off technique performed by the way of electron beam lithography. Lift–off is a technique mainly used for preparation of metallic patterns and unlike etching it is an additive technique using a sacrificial material – e.g. e–beam resist PMMA. In this paper we discussed technique of preparation of lift–off mask on two different e–beam writing systems. The first system was BS600 – e–beam writer with rectangular variable shaped beam working with 15keV. The second system was Vistec EBPG5000+ HR – e–beam writer with Gaussian shape beam working with 50 keV and 100 keV. The PMMA resist single layer and bi–layer was used for the lift–off mask preparation. As a material for creation of metallic pattern, magnetron sputtered chromium was used. Atomic force microscope, scanning electron microscope and contact profilometer were used to measure and evaluate the results of this process.
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Current state and prospects of scintillation materials for detectors in SEM
Schauer, Petr ; Bok, Jan
The two principal quantities are important for assessing the quality of each imaging system. Firstly, it is the detective quantum efficiency (DQE), which is primarily a measure of image noise. As the DQE is determined by signal to noise ratio (SNR), the efficient and noise-free components are the key to the high DQE. Second, not less important indicator of image quality is also the modulation transfer function (MTF). MTF describes the ability of adjacent pixels to change from black to white in response to patterns of varying spatial frequency, and hence it determines the actual capability to show fine detail, whether with full or reduced contrast. Using a scanning imaging system the fast components are the key to the good MTF. In a scintillation electron detector of scanning electron microscope (SEM) the scintillator is the most crucial component, because it significantly influences both the DQE and MTF. The aim of this study is to assess the scintillation materials suitable for SEM detectors characterized by the both high efficiency and fast decay characteristic.
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Electron beam cutting of non-metals
Dupák, Libor
Various materials are difficult to cut or drill, e.g. due to their mechanical properties (hardness, fragility). Also, sometimes the required hole shape and dimensions may be difficult to obtain by mechanical machining or the efficiency of such process is low. Electron beam machining is one way to overcome these issue. It is based on the melting and evaporation of the material by the intense electron beam. The presented experiments were performed on the desktop electron beam welder MEBW-60/2, developed at the Institute of Scientific Instruments AS CR, v.v.i. at Brno. It is also manufactured and sold by the Focus GmbH company under licence. In the following experiments, several sets of grooves were prepared, both in quartz glass and AI2O3 ceramics, to find out the influence of various beam parameters on groove dimensions. The experimental conditions were as follows: acceleration voltage 50 kV, beam current 0.1-1 mA, machining speed 2.5-50 mnvs'1.
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Quality assessment of scintillation detector in SEM using MFT
Bok, Jan ; Schauer, Petr
One of the recent trends in S(T)EM is increasing of the e-beam scanning speed. In general, higher speeds decrease object degradation and prevent image artifacts caused by slow electrical discharging. However, the increase of the scanning speed is limited by the time response of the segnal-electron detector. When the detector response is slower than the scanning speed, it can have negative influence to the quality of the scanned image, such as contrast reduction and image blurring. Usually, the rise and fall edges of the time response curve to a square electron pulse have more complex form, such as a multi-exponential function of time. Evaluate and compare the time-dependent edges in contex of their influence on the image quality is rather complicated. Therefore, we propose to express the detector time response by the modulation transfer function (MTF), which contains all relevant information. It can give the answer to the important question, what maximum scanning speed can be used not to significantly decrease the image quality.
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