Národní úložiště šedé literatury Nalezeno 111 záznamů.  začátekpředchozí78 - 87dalšíkonec  přejít na záznam: Hledání trvalo 0.00 vteřin. 
Measurement of current density distribution in shaped e-beam writers
Horáček, Miroslav ; Bok, Jan ; Kolařík, Vladimír ; Urbánek, Michal ; Matějka, Milan ; Krátký, Stanislav
The ZrO W(100) Schottky cathode is used in our e-beam writing system working with a rectangular-shaped electron beam. The homogeneous angular current density distribution is crucial for quality of exposures of the shaped beam lithography systems. Two basic types of the angular emission distribution can be observed in dependence on the microscopic final end form shape of the emitter tip, with bright centre and more common dark centre. The stable operation of the cathode thus stable end form shape requires a delicate balance of parameters inside the gun which however can slightly change during cathode life time. This implies the necessity of analysing and periodical monitoring the current density distribution in e-beam. Four methods enabling this measurement are presented.
Influence of Carrying Frequency Phase Shift of Synthetic Jet Generator on The Noise
Pick, P. ; Matějka, Milan ; Skála, V.
The main topic of this article is the influence of phase shift of neighbouring synthetic jet generators to the flow field past a hump and noise reduction. Syntheetic jet generators are placed in the hump in front of point of boundary layer separation. The carrying frequency of actuating signal, wich is driving the synthetic jet generator, is shifted for about 180°. The modulated frequency, which corresponds to the shading frequency of the flow, is superposed on the carrying signal. Finally, the benefits of phase shift signal of neighbouring synthetic jet generators are described, as far as the produced noise and the total loss coefficient decrease are concerned.
CTA Measurement of Longitudinal Velocity Fluctuation and ITS Spectra in Thermal Convection Atmosphere and Lee-Wawe Condition Using Sailplane in-Flight Experiment
Popelka, Lukáš ; Matějka, Milan ; Zelený, L. ; Uruba, Václav
Two typical environments of large scale turbulent mixing in lower troposphere section were studied using sailplane in-flight experiment. Key properties, such as intensity and spectra were measured, indicating vortices decay into the smaller scales. In both cases, identified spectra extend above 1 kHz, hence containing disturbances capable to influence transition of laminar boundary layer to turbulence on sailplane (aircraft) wing.
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.
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.
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.
Microstructuring of metallic layers for sensor applications
Kolařík, Vladimír ; Krátký, Stanislav ; Urbánek, Michal ; Matějka, Milan ; Chlumská, Jana ; Horáček, Miroslav
This contribution deals with a patterning of thin metallic layers using the masking technique by electron beam lithography. It is mainly concentrated on procedures to prepare finger structure in thin Gold layer on electrically isolated Silicon wafer. Both positive and negative tone resists are used for patterning. The thin layer is structured by the wet etching or by the lift-off technique. The prepared structures are intended to be used as a conductivity sensor for a variety of sensor applications. Patterning of the thin layer is performed by the e-beam writer with shaped rectangular beam BS600 by direct writing (without the glass photo mask). Besides the main technology process based on the direct-write e-beam lithography, other auxiliary issues are also discussed such as stitching and overlay precision of the process, throughput of this approach, issues of the thin layer adhesion on the substrate, inter-operation control and measurement techniques.
Pneumatická měření na mříži TR-U-4
Šimurda, David ; Luxa, Martin ; Matějka, Milan
Zpráva se zabývá výsledky pneumatických měření na profilové mříži, která je modelem špičkového řezu dlouhé turbínové lopatky (délka: 1375mm, 52 lopatek v kole).
Optická měření na mříži TR-U-4
Luxa, Martin ; Šimurda, David ; Matějka, Milan
Zpráva se zabývá výsledky optických měření na profilové mříži, která je modelem špičkového řezu dlouhé turbínové lopatky (délka: 1375mm, 52 lopatek v kole).
Měřící prostor pro mříže s malým otočením proudu
Matějka, Milan ; Luxa, Martin ; Šimurda, David
Ve zprávě je podrobně popsána konstrukce měřicího prostoru pro mříže s malým otočením proudu. Funkce měřicího prostoru je doložena výsledky měření na špičkové lopatkové mříži.

Národní úložiště šedé literatury : Nalezeno 111 záznamů.   začátekpředchozí78 - 87dalšíkonec  přejít na záznam:
Viz též: podobná jména autorů
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2 Matějka, Miroslav
1 Matějka, Miroslav Pacifik
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