|
| |
|
|
Multidimensional interferometric measuremenr system for AFM microscopy - national standard for nanometrology
Hrabina, Jan
We present the design and performance characteristics of 6-axis interferometric measurement system for local probe microscopy. Described measurement tool was developed in colaboration with the Czech Metrological Institute in Brno and it is intended to solve as a national nanometrological standard. The system in based on a commercial nanopositioning sample table controlled by piezoelectric transducers, a metrological frame and a laser interferometric setup for dimensional measurements in six degrees of freedom.
|
|
|
Detection standing wave within Fabry-Perot Cavity
Holá, Miroslava
This contribution follows up with project Interferometry with compensation of the refractive index of air. This inteferometric technique was based on differential interferometry setup for measurement in the subnanometer scale in atmospheric conditions. One of the important limiting factor in any optical measurement are fluctuations of the refractive index of air representing a source of uncertainty on the 10-6 level when evaluated indirectly from the physical parameters of the atmosphere. Our proposal is based on the concept of overdetermined interferometric setup where the reference length is derived from a mechanical frame made from a material with very low thermal coefficient on the 1*E-8 level (Zerodur - Schott). The optical setup consists of three interferometers sharing the same beam path where two measurement differentially the displacement while the third evaluates the changes in the measuring range acting as a tracking refractometer. The concept of stabilization of wavelength against the mechanical reference is realized within passive Fabry-Perot cavity. The link between the wavelength and mechanical reference here is in principle simple, the laser optical frequency has to be locked to the resonance of the passive cavity either through tracking the transmission maximum or reflection minimum. The key component for position sensing inside of a passive Fabry-Perot cavity is low-loss transparent photodetector. The transparent photodetector made in cooperation with Institute of Physics of the ASCR - Department of Thin Films and Nanostructures (work group A. Fejfar). Transparent photodetector is made of fused silica substrate, active photo resistive silicon layer with side titanium electrode and a set of antireflection coatings optimized for minimum reflectivity. Optimized AR coating for 532 nm.
|
|
|
Nanopositioning with detection of a standing wave
Holá, Miroslava ; Hrabina, Jan ; Číp, Ondřej ; Fejfar, A. ; Stuchlík, J. ; Kočka, J. ; Oulehla, Jindřich ; Lazar, Josef
A measuring technique is intended for displacement and position sensing over a limited range with detection of standing-wave pattern inside of a passive Fabry-Perot cavity. In this concept we consider locking of the laser optical frequency and the length of the Fabry-Perot cavity in resonance. Fixing the length of the cavity to e.g. a highly stable mechanical reference allows stabilizing wavelength of the laser in air and thus to eliminate especially the faster fluctuations of refractive index of air due to air flow and inhomogeneity. Detection of the interference maxima and minima within the Fabry-Perot cavity along the beam axis has been tested and proven with a low loss transparent photodetector with very low reflectivity. The transparent photodetector is based on a thin polycrystalline silicon layer. Reduction of losses was achieved thanks to a design as an optimized set of interference layers acting as an antireflection coating. The principle is demonstrated on an experimental setup.
|
|
|
Interferometric coordinates measurement sytem for local probe microscopy nanometrology
Hrabina, Jan ; Lazar, Josef ; Klepetek, P. ; Číp, Ondřej ; Čížek, Martin ; Holá, Miroslava ; Šerý, Mojmír
We present an overview of new approaches to the design of nanometrology measuring system with a focus on methodology of nanometrology interferometric techniques and associated problems. The design and development of a nanopositioning setup with interferometric multiaxis monitoring and control involved for scanning probe microscopy techniques (primarily atomic force microscopy, AFM) for detection of the sample profile is presented. Coordinate position sensing allows upgrading the imaging microscope techniques up to quantified measuring. Especially imaging techniques in the micro- and nanoworld overcoming the barrier of resolution given by the wavelength of visible light are a suitable basis for design of measuring systems with the best resolution possible. The system is being developed in cooperation with the Czech metrology institute and it is intended to operate as a national nanometrology standard combining local probe microscopy techniques and sample position control with traceability to the primary standard of length.
|
|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
Precision displacement interferometry with stabilization of wavelength on air
Lazar, Josef ; Holá, Miroslava ; Hrabina, Jan ; Buchta, Zdeněk ; Číp, Ondřej
We present an interferometric technique based on differential interferometry setup for measurement in the subnanometer scale in atmospheric conditions. The motivation for development of this ultraprecise technique is coming from the field of nanometrology. The key limiting factor in any optical measurement are fluctuations of the refractive index of air representing a source of uncertainty on the 10'6 level when evaluated indirectly from the physical parameters of the atmosphere. Our proposal is based on the concept of overdetermined interferometric setup where a reference length is derived from a mechanical frame made from a material with very low thermal coefficient on the 1 O'8 level. The technique allows to track the variations of the refractive index of air on-line directly in the line of the measuring beam and to compensate for the fluctuations. The optical setup consists of three interferometers sharing the same beam path where two measure differentially the displacement while the third represents a reference for stabilization of the wavelength of the laser source. The principle is demonstrated on an experimental setup and a set of measurements describing the performance is presented.
|
|
| |
guest ::
