The energy deposited in resist during its exposure by ion beam was simulated for ions from a set of rare gases and for gallium. It was shown that the distribution of energy density can be approximated by the product of two Gaussian functions. One of them describes the lateral distribution of energy, the second the dependence on depth. The widths and centres of these Gaussian functions are determined by the energy length (also mentioned in the literature as "Range" or "mean length of trajectories"), the mass of ions and the average atomic number of resist. The obtained description would make it possible to estimate the size of the resist modified volume for any type of ion with energy of tens keV. So it can be used for a priori estimates of resolution and performance, as well as for the choice of beam energy and ion type based on this. Keywords: lithography, nanostructuring, ion beam, resist, modeling, deposited energy.

One of the ways to use a focused ion beam in lithographic processes to create nanostructures is through the exposure of special sensitive materials, i.e., resists. As a result of exposure, the solubility of such a material increases ("positive" resist) or, conversely, decreases ("negative" resist). Subsequent selective irradiation and development of the resist make it possible to create a predetermined pattern on the substrate. This work is aimed at developing the theoretical foundations for this ion lithography method. A practically important case of stopping heavy ions in an organic resist, the average atomic mass of which is much less than the mass of the incident ion, is considered. Expressions for the "energy" and transport lengths of ions are obtained. The calculations are carried out assuming a power-law interaction potential. The "energy" length characterizes the depth of penetration of ions into the material, and the transport length is related to beam expansion due to scattering. Therefore, these lengths are the main characteristics of the zone in which the ion-beam energy is absorbed.

The feature of the promising tool of lithographic nanostructuring based on selective exposure of polymer resist by ion beam is very compact (of about tens of nanometers) beam interaction volume. Herewith the main part of beam energy is deposited in the resist and is spent to its modification. It causes the set of advantages specific for this method: sub-10 nanometer resolution achievable, very high energy efficiency and almost complete absence of proximity effect. But also due to this feature absorbed doze essentially inhomogeneous in resist and the dissolution rate is strongly dependent on depth. So the common procedure of resist contrast determination cannot be applied anymore. In the present work a new method for resist contrast determination considering the relation between dissolution rate and deposited energy density is suggested and realized. By using it for PMMA resist irradiated by 30 keV Ga+ ion beam the value of contrast was determined to be 3.1 and ions energy length was estimated to be 42 nm.

The use of a special device that limits the field of view of a detector, i.e., a confocal collimator, is one of the approaches to obtaining information about the spatial distribution of the detected material in the methods for radionuclide diagnostics (in medicine) and X-ray fluorescence analysis (in material science). This device is a monolithic construction with a large number of straight channels whose axes are directed towards a single point that is the focus of the confocal collimator. The possibility of fabricating confocal collimators using 3D printing technology is demonstrated. The advantages of 3D printing are simplicity, reliability, and wide availability. It is shown that the use of a confocal collimator in radionuclide diagnostics instead of a single-channel collimator is advantageous, since it substantially increases the sensitivity (by 2−7 times) with the simultaneous improvement of the resolution (approximately by 9 times). The applicability of the confocal collimator for determining the depth of occurrence of a radiation source, i.e., for measuring the three-dimensional distribution of the emitting (fluorescent) substance, is also demonstrated.

The paper considers one of the methods of micro - and nano - images formation with high accuracy of process control – electronic lithography. Comparing to other nanostructuring technologies, such as photolithography in particular, electronic lithography is more versatile. This paper describes the technological processes of electron lithography on a silicon substrate using a polymer-based resist PMMA. The irradiation was carried out in the SEM chamber by electrons with an energy of 5 keV, 15 keV, 30 keV and an exposure dose of 1-10000 µС/cm2. The analysis of the obtained samples using optical and atomic force microscopy (AFM) showed the dependence of the color and the corresponding thickness of the resist on the radiation dose. The calculation of such parameters as positive and negative sensitivity and contrast was carried out on the basis of the resist thickness profiles.

This work deals with TRAP-KS code verification. TRAP-KS is used for coupled neutron and thermo-hydraulic process calculations of VVER reactors. The three-dimensional neutron kinetics model enables consideration of space effects, which are produced by energy field and feedback parameters variations. This feature has to be investigated especially for asymmetrical multiplying variations of core properties, power fluctuations and strong local perturbation insertion. The presented work consists of three test definitions. First, an asymmetrical control rod (CR) ejection during power operation is defined. This process leads to fast reactivity insertion with short-time power spike. As second task xenon oscillations are considered. Here, small negative reactivity insertion leads to power decreasing and induces space oscillations of xenon concentration. In the late phase, these oscillations are suppressed by external actions. As last test, an international code comparison for a hypothetical main steam line break (V1000CT-2, task 2) was performed. This scenario is interesting for asymmetrical positive reactivity insertion by decreasing coolant temperature in the affected loop.

The current induced by the radiation from a 63Ni film of variable thickness is simulated taking into account the real spectrum of emitted electrons and their angular distribution for GaN. The efficiency of β-radiation detectors made from Si and SiC is estimated based on the results obtained in this paper and previously. Using a scanning electron microscope the efficiency of β-radiation detectors made from Si and SiC under conditions corresponding to β radiation from a Ni film with a thickness of 3 μm and activity of 10 mCi/cm2 is analyzed. It is shown that the efficiency of real Si-based structures is virtually as good as the efficiency of SiC-based structures.

Here we present an approach for creating full-color digital rainbow holograms based on mixing three basic colors. Much like in a color TV with three luminescent points per single screen pixel, each color pixel of initial image is presented by three (R, G, B) distinct diffractive gratings in a hologram structure. Change of either duty cycle or area of the gratings are used to provide proper R, G, B intensities. Special algorithms allow one to design rather complicated 3D images (that might even be replacing each other with hologram rotation). The software developed ("RainBow") provides stability of colorization of rotated image by means of equalizing of angular blur from gratings responsible for R, G, B basic colors. The approach based on R, G, B color synthesis allows one to fabricate gray-tone rainbow hologram containing white color what is hardly possible in traditional dot-matrix technology. Budgetary electron beam lithography based on SEM column was used to fabricate practical examples of digital rainbow hologram. The results of fabrication of large rainbow holograms from design to imprinting are presented. Advantages of the EBL in comparison to traditional optical (dot-matrix) technology is considered.

Приведены результаты измерений поверхностного потенциала зарядки пленок ПММА различной толщины под воздействием облучения электронными пучками различной энергии. Даны соответствующие диапазоны энергий первичных электронов для случаев как положительной, так и отрицательной зарядки диэлектриков. Показано, что для каждого значения толщины ПММА резиста существуют две индивидуальные критические энергии электронов, при которых резист не заряжается, и которые могут быть рекомендованы для низковольтной и высоковольтной электронной нанолитографии с минимальными ошибками позиционирования луча. Эксперименты показали очень высокое значение критического напряжения пробоя ПММА-пленки, величиной порядка 107 В/см.

Results of the measurement of the surface charging potential for PMMA films of various thicknesses under the effect of irradiation by electron beams of various energies are presented. The corresponding energy ranges of primary electrons are given for the cases of both positive and negative charging of the dielectrics. It is shown that two individual critical electron energies exist for each thickness of the PMMA resist, at which the resist is not charged. These energies can be recommended for low-voltage and high-voltage electron nanolithography with minimal errors in beam positioning. The experiments showed a very high value of the critical breakdown voltage of the PMMA film of about 107 V/cm.

Development of a technological basis for the fabrication of diffraction optical elements has been underway at Synchrotron SOLEIL since April 2009. These diffraction focusing elements are: zone plates and condenser lenses for soft x-rays (80-2500 eV), focusing zone plates for hard x-rays (4-24 keV), and diffraction elements working under complete external reflection conditions with elliptical diffraction zones and a topology appropriate to operate at a glancing incidence to fulfill the conditions of total external reflection (energy range 100-1500 eV). This work discusses fabrication of circular germanium-based zone plates and results of numerical calculations of the behavior of zone plates with real topologies under real experimental conditions. The software used for these calculations allows us to take into account the undercut of zones that occurs after plasmachemical etching as well as variations in the zone heights. Such variations could be used to correct or improve zone plate efficiency after electroplating or plasmachemical etching and can be performed by a focused ion beam etching [1] (direct or with active gas assistance). Data preparation and ion beam control for these corrections can be carried out by Nanomaker software (Interface Ltd).

This paper experimentally demonstrates that a quantitative description of focused ion beam (FIB) milling (at least for several 3D profiles with inclination not higher than 450) can be done by means of an isotropic local etching model. Specific characteristic of this model is that it does not account for re-deposition.The paper also presents IonRevSim - Software developed specifically for data preparation and prediction of the shape of the FIB machined structures. Those functions and their operating modes are discussed here in detail and FIB experimental results are provided to verify the algorithms embedded in the software. (C) 2009 Elsevier B.V. All rights reserved.

The paper demonstrates that the ion beam milling process can be modelled as a local isotropic etching without taking into account the material re-deposition during the sputtering. It also presents a software, IonRevSim, specifically developed to simulate the 3D ion structuring and thus to validate the milling process and if necessary to optimise off-line its processing parameters. In particular, employing the IonRevSim software it is possible to prepare the necessary data for performing 3D ion milling and then to simulate the 3D structuring process with the aim to minimise the deviation of resulting machined surface from the targeted one. These two main functions of the software and their respective operating modes are discussed in the paper. An experimental verification based on an optimised data generated by IonRevSim was performed using both FIB and multi-beam CHARPAN PMLP tools. For both ion-patterning techniques a good agreement between experimental and simulation results was demonstrated when applied for producing relatively low aspect ratio structures.

Classical methods for contrast measuring do not consider change of absorbed dose with resist depth. In the work absorbed dose distribution in resist was calculated by Monte-Carlo method and the absorbed dose increasing from resist surface to substrate was found. An approach for the resist contrast determination insensitive to dose variations with depth was proposed. Using the method resist contrast is obtained and compared with resist contrast measured by classical methods. A relation between these two values was derived. The comparison showed that dependence of absorbed dose with resist depth results effectively to increase of contrast value measured with classical methods, the increase is sometimes rather significant.

The approach based on the nano-indenter developed for viscosity characterization allows temperature measurement of thermoplastic, thermo- and photo-curable polymers (materials used in NILand UV-NIL) with sub-micron resolution. It could be used in design, tailoring and optimisation of soft matter for different application. In particular:Recommended imprint temperature can be deduced from nano-probe experiments.Optimal curing time as function of temperature can be established.Prediction on mechanical properties at imprint temperature easily can made.Surface adhesivity as function of temperature can be measured

The IMPRINT software is applied for simultaneous calculation of the resist viscous flow in thermal nanoimprint lithography (NIL) and the stamp/substrate deformation. From the presented comparison of calculated and experimental results, it can be concluded that the simulation allows predicting the residual layer thickness with accuracy better than 10%. The obtained results demonstrate the potential of the IMPRINT software as an efficient tool for choosing NIL process parameters and the optimization of the NIL stamp geometry.

A refined version of the IMPRINT software is applied for simultaneous calculation of the resist viscous flow in thermal nanoimprint lithography and the stamp/substrate deformation. This version applies a modified coarse-grain method as well as takes into account the composition and elastic properties of the imprint setup (the stamp/substrate + “pressure buffer layers”). The presented comparison of calculated and experimental results confirms the potential of the IMPRINT software as an efficient tool for the reduction of the stamp bending.