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What is the buzz about the TZ mode
Kolařík, Vladimír ; Matějka, František ; Matějka, Milan ; Horáček, Miroslav ; Urbánek, Michal ; Bok, Jan ; Krátký, Stanislav ; Král, Stanislav ; Mika, Filip
This contribution deals with an e-beam pattern generator BS 600 that works with a variable rectangular spot of electrons (stamp). The TZ stands for the ‘technology zoom’; its meaning is a reduction of the spot size by a factor of 3. Original description of the TZ exposure mode can be found in (1), [2] and [3]; further aspects concerning the exposure system and its electron source were described in [4] and [5]; technology and related topics are discussed in [6], [7], [8] and [9]; overview of application areas is in [10], [11] and [12]; and finally, very recent results are summarized in [13], [14] and [15].
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Thermal-field electron emission W(100)/ZrO cathode: facets versus edges
Matějka, František ; Horáček, Miroslav ; Kolařík, Vladimír ; Matějka, Milan
The tungsten cathode in the thermal-field emission (TFE) regime can achieve significantly higher angular current density in comparison with the Schottky cathode. The Schottky emission regime is located between the thermal emission regime and the cold field emission regime. The typical operation electric field is 0,1 - I V/nm and tip radius varies from 0.3 to 1.0 im . The thermal-field regime is located between the Schottky regime and the cold field emission regime. In the cold field emission regime the electron tunnelling is a dominant mechanism due to the electric field higher than 1 V/nm. The TFE is a combination of the field supported thermal emission and the field emission under the higher electric field. The radius of the thermal-field emitter should be lower in comparison with the Schottky emitter.
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Surface crystallinity at the sight of electrons
Frank, Luděk ; Mikmeková, Šárka ; Mika, Filip ; Müllerová, Ilona
Scattering of electrons, injected into solids in order to produce an electron optical image of their surfaces, is governed by inner potentional of the sample with its spatial distribution inherent to the target structure. Except truly amorphous materials of the spatial arrangement range shorter than the interaction volume of electrons, we meet anisotropic scattering with the resulting image signal responding to the local crystalline structure. Incident electrons undergo scattering events the number of wich depends on their energy and on the scattering cross section of the material and the final emitted current results from statistics of these events.
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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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Measurements of current density distribution in e-beam writer
Bok, Jan ; Kolařík, Vladimír
An e-beam writer with a variable shaped beam needs a bright and stable source of electrons but also a homogeneous square beam segment. This is the starting element out oif wich smaller rectangular-shaped variable-sized patterns are selected (stamps). Current inhomogeneity of the starting element would cause and different current density of various stamps that negatively impacts the exposure quality. This problem implies the necessity of analysing and monitoring the current density distribution in the staring beam element.
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