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Electrostatic Deflection and Correction Systems
Badin, Viktor ; Oral, Martin (referee) ; Zlámal, Jakub (advisor)
The aim of this master's thesis is to explore and study dynamic aberration correction options in electron-beam lithography systems. For the calculations, the thesis uses the optical column of the BS600 electron-beam writer. The thesis focuses on corrections of the third order field curvature, astigmatism, and distortion aberrations of the currently used magnetic deflection system and a newly designed electrostatic deflection system. The parameters of the two deflection and correction systems were compared.
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Influence of saddle deflection coils inaccuracy on image aberrations
Mičulka, Martin ; Oral, Martin (referee) ; Sháněl, Ondřej (advisor)
Tato práce se zabývá výpočtem parazitických magnetických polí neseřízené deflekční cívky z důvodu výrobních nepřesností. Vztah mezi multipólovými magnetickými poli a asymetrickým rozložením vynutím elektronové vychylovací cívky je rozebrán. Nové a rychlé 2D metody výpočtu jsou představeny. Výsledky jsou poté porovnány s 3D metodou konečných prvků a s experimentem. Vliv multipólových parazitických polí způsobených nepřesností výroby na astigmatismus je tak v důsledku prošetřen.
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Influence of saddle deflection coils inaccuracy on image aberrations
Mičulka, Martin ; Oral, Martin (referee) ; Sháněl, Ondřej (advisor)
Tato práce se zabývá výpočtem parazitických magnetických polí neseřízené deflekční cívky z důvodu výrobních nepřesností. Vztah mezi multipólovými magnetickými poli a asymetrickým rozložením vynutím elektronové vychylovací cívky je rozebrán. Nové a rychlé 2D metody výpočtu jsou představeny. Výsledky jsou poté porovnány s 3D metodou konečných prvků a s experimentem. Vliv multipólových parazitických polí způsobených nepřesností výroby na astigmatismus je tak v důsledku prošetřen.
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Inelastic mean free path from raw data measured by low-energy electrons time-of-flight spectrometer
Zouhar, Martin ; Radlička, Tomáš ; Oral, Martin ; Konvalina, Ivo
The inelastic mean free path (IMFP) is a key parameter of electron transport in a solid. With\nthe rise of so-called meta-materials, materials of specific shape, such as 2D crystals, or\nmaterials with tailored functionality for next-generation electronic devices, the investigation\nof the IMFP is still topical and of high importance. This is true especially at low energies, landing energy of electrons below 100 eV, that are hard to study using well established\ntechniques of electron spectroscopy.
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Electron optical properties of a new low-energy scanning electron microscope with beam separator
Radlička, Tomáš ; Kolařík, V. ; Oral, Martin
The low energy scanning electron microscope (SEM) which is currently at the Institute of\nScientific Instruments, suffers from low resolution and suboptimal detections systems. In the cathode lens regime, signal electrons are accelerated by the electric field between the sample and the objective lens, getting collimated. Those with low emission angles get through the bore in the BSE detector into the objective lens and cannot be detected by the available detectors now. The information about the sample provided by these electrons is lost, which limits our microscopy methods.\nThese two limitations are to be overcome with a new low-energy SEM, which was developed\nat Delong Instruments. It consists of a field emission gun with the energy width of 0.8 eV, a magnetic condenser lens, and an electrostatic triode objective lens. The acceleration voltage is 5 kV. The sample stage can be biased at up to -5 kV to provide low landing energy without strong decrease of the resolution – the effect of the cathode lens. A beam separator is placed in front of the deflection system for the detection of the signal electrons that get to the column. In a combination with standard detectors and cathode lens, it allows detecting all\nkinds of signal electrons.
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Analysis of linear ion Paul traps using 3-D FEM and the azimuthal multipole expansion
Oral, Martin ; Číp, Ondřej ; Slodička, L.
Radiofrequency (RF) Paul traps are valuable in the design and in the operation of highly stable\noptical atomic clocks based on suitable trapped ions. The traditional setup involves a single\nion in an RF trap irradiated with a laser beam. The frequency of the laser light is then fine-tuned to match that of photons coming from an electronic transition in the atomic shell. The\nachievable frequency stability is about 10-17 for laser-cooled ions. However, the stability can be\nfurther improved by using heavy atoms (such as Thorium) and the more stable frequencies of\ntheir nuclear transitions, and by setting up so-called Coulomb crystals, to improve the frequency measurement statistics by increasing the number of reference atoms. These techniques and their combination could reach relative stabilities beyond 10-20.
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Degradace motorového oleje ve vznětovém motoru osobního automobilu
Oral, Martin
The thesis is focused on the problems of degradation of engine oils of the same viscosity class 5W-30.The first part of the thesis is describing lubricating systems and their component parts. The thesis also focuses on the division of oil in each classification and description of its properties. Samples of the oil have been taken from two cars with identical diesel engine, but with different total traveling distance. Attention is paid to the amount of structural metals, contaminants and additives in both oils, and throughout the oil usage interval. The results are interpreted graphically and various dependencies are modeled using appropriate regression functions. Thesis compares the mechanical and physical properties of engine oils, depending on mileage. The conclusion summarizes the evaluation and the results obtained.
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Correction of misalignment aberrations of a hexapole corrector using the differential algebra method
Radlička, Tomáš ; Oral, Martin
Overcoming the limitations of the Schertzer theorem is a long story in electron microscopy. Although the basic principle of a spherical aberration (C3) correction was suggested as early as in 1947 the first experimental correctors of spherical aberration were only realized in the last decade of the 20th century. The recent multipole correctors are designed for high-energy\nTEM or STEM, where the corrector system enables reaching the atomic resolution. On the other\nhand, the corrector for low-energy SEM has been developed but this type of corrector must also contain chromatic aberration (Cc) correction to reduce the effect of the non-zero energy width. Recently, the energies of SEM reach 30 keV and transmission mode (TSEM) is a standard part of the instrument. Standard resolution in TSEM is about 0.6 nm and it is limited by C3. Reaching atomic resolution with this set-up is not a real expectation because of its instability, but the resolution of about 0.2 nm would increase the field of applications. Corrector for these type of instruments should be (a) simple, compact and cheap (b) only spherical aberration of the third,\noptionally the fifth order must be corrected (c) effect of the chromatic aberration may be reduced by energy filtering. We studied design based on Rose’s hexapole corrector.
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