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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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Variable-shape E-beam litography: Proximity effect simulation of 3D micro and nano sructures
Matějka, Milan ; Urbánek, M. ; Kolařík, V. ; Horáček, M. ; Krátký, Stanislav ; Mikšík, P. ; Vašina, J.
A proximity effect simulation technique and developed resist profile simulation for variable-shaped e-beam lithography of three dimensional structures are presented. The e-beam lithography is a technology process which allows high resolution patterning. Most frequently it is used for microfabrication or nanofabrication of two dimensional relief structures such as resist photo masks, etching masks, diffraction gratings, micro and nano optics, photonics and more. However, in the case of the 3D structures patterning the precise thickness control of developed resist is required. With regard to subsequent proximity effect correction, the proximity effect simulation and developed resist profile simulation models are in the case of 3D structures fabrication critically important. We show the results from simulation of exposure and resist development process for the chosen polymer resist (PMMA), using the patterning and simulation e-beam lithography software.
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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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