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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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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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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.
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E-beam pattern generator BS600 and technology zoom
Kolařík, Vladimír ; Horáček, Miroslav ; Matějka, František ; Matějka, Milan ; Urbánek, Michal ; Krátký, Stanislav ; Král, Stanislav ; Bok, Jan
This contribution deals with an electron beam pattern generator (ELG) working with a rectangular shape variable size electron beam originally developed at Institute of Scientific Instruments (ISI), later on commercialized as a BS600 series by former company Tesla, and recently upgraded by ISI cooperating with several partners. The key issue of this paper is a recently developed exposure mode which is called Technology Zoom (TZ mode) since its original concept until the recent progress. This ELG operating in the TZ mode provides three main advantages when compared to the standard exposure mode: higher exposure speed due to increased beam current density; finer stamp size adjustment and sharper stamp shape due to the stronger size reduction of the shaping aperture. Further, we discussed also some drawbacks and practical issues of the TZ mode. And finally, we summarize some results on real exposure examples. The new exposure mode (together with other recent upgrades) makes the BS600 pattern generator very useful for the nanotechnology patterning tasks and challenges.
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Nano modification of the W(100)/ZrO electron emitter tip using reactive ion etching
Horáček, Miroslav ; Matějka, František ; Kolařík, Vladimír ; Matějka, Milan ; Urbánek, Michal
The W(100)/ZrO electron emitter tip is typically prepared from a tungsten single-crystal shaft of a diameter of 125 μm using electrochemical anodic etching. In order to prepare an emitter for e-beam writer with a shaped beam it is desirable to etch the tip with a radius around 100 nm. Despite the anodic etching is precisely controlled using dedicated software, the desired final form shape of the emitter tip is not achieved in every case. The correcting anodic etching is not possible due to the technology principle of the etching itself. We present in this contribution the procedure that modifies/repairs the tungsten tip shape in a nanoscale region using a reactive ion etching (RIE) in CF4 + O2 gaseous mix in a barrel type reactor at the radio frequency of 13,56 MHz and the working pressure of 1000 Pa. The change of the geometry after the RIE process is checked using a high resolution scanning electron microscope. The influence of the tip modification of the activated thermal-field W(100)/ZrO electron emitter on its emission characteristics is also presented.
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Shaped E-beam nanopatterning with proximity effect correction
Urbánek, Michal ; Kolařík, Vladimír ; Matějka, Milan ; Matějka, František ; Bok, Jan ; Mikšík, P. ; Vašina, J.
Electron beam writer is a tool for writing patterns into a sensitive material (resist) in a high resolution. During the patterning, areas adjacent to the beam incidence point are exposed due to electron scattering effects in solid state (resist and the substrate). Consequently, this phenomenon, also called proximity effect, causes that the exposed pattern can be broader in comparison to the designed. In this contribution we present a software for proximity effect simulation and a software for proximity effect correction (PEC). The software is based on the model using the density of absorbed energy in resist layer and the model of resist development process. A simulation of proximity effect was carried out on binary lithography patterns, and consequently testing patterns were exposed with a corrected dose. As pattern generation, we used the e-beam writer TESLA BS 600 working with fixed energy 15keV and variable size rectangular shaped beam. The simulations of binary testing patterns and exposed patterns without PEC were compared. Finally, we compared the testing structures with PEC and without PEC, and we showed that the PEC tool works reliably for the e-beam writer BS 600.
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Calibration specimens for microscopy
Kolařík, Vladimír ; Matějka, Milan ; Matějka, František ; Krátký, Stanislav ; Urbánek, Michal ; Horáček, Miroslav ; Král, Stanislav ; Bok, Jan
Recent developments in nanotechnologies raised new issues in microscopy with nanometer and sub nanometer resolution. Together with the imaging techniques, new approaches in the metrology field are required both in the direct metrology issues and in the area of calibration of the imaging tools (microscopes). Scanning electron microscopy needs the calibration specimens for adjusting the size of the view field (correct magnification) and the shape of that field (correction of deflection field distortions). Calibration specimens have been prepared using different technologies; among them the e–beam patterning and the e–beam lithography have been proved to be appropriate and flexible tool for that task. In the past, we have reported several times our achievements in this field (e.g. [1]). Nevertheless, recent advances of the patterning tool (BS600), mainly the development of the technology zoomed exposure mode [2] and the installation of the magnetic field active cancellation system [3], pushed remarkably the technology necessary for further advances in this area. Within this contribution some theoretical, technology and practical aspects are discussed; achieved results are presented.
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Analysis of electron current instability in E-beam writer
Bok, Jan ; Horáček, Miroslav ; Král, Stanislav ; Kolařík, Vladimír ; Matějka, František
The electron beam writer Tesla BS600 works with a thermal-field electron emitter, fixed electron energy of 15 keV and a rectangular shaped variable-size electron beam. The size of the shaped beam (stamp) can be set from 50 to 6300 nm in standard mode and from 16 to 2100 nm in high-resolution mode. The basic increment of the stamp size is 50 nm, resp. 16 nm. Electron current density inhomogeneity and long-term instability in stamps can have negative impact on the exposure quality. Therefore, we focused on a study of the current time instability. The current density in variously sized stamps was measured by a picoammeter and a PIN diode video channel as a function of time. We analyzed short-term and long-term current instabilities using filtering techniques, as well as the Fourier analysis. Based on the results, we could be able to find reasons of the current instabilities and to propose improvements to achieve higher exposure quality.
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