Theory and Applications of X-ray Standing Waves in Real Crystals

Theoretical aspects of x-ray standing wave method for investigation of the real structure of crystals are considered in this review paper. Starting from the general approach of the secondary radiation yield from deformed crystals this theory is applied to different concreat cases. Various models of deformed crystals like: bicrystal model, multilayer model, crystals with extended deformation field are considered in detailes. Peculiarities of x-ray standing wave behavior in different scattering geometries (Bragg, Laue) are analysed in detailes. New possibilities to solve the phase problem with x-ray standing wave method are discussed in the review. General theoretical approaches are illustrated with a big number of experimental results.Comment: 101 pages, 43 figures, 3 table

The antibacterial activity of acetic acid against biofilm-producing pathogens of relevance to burns patients

Introduction: Localised infections, and burn wound sepsis are key concerns in the treatment of burns patients, and prevention of colonisation largely relies on biocides. Acetic acid has been shown to have good antibacterial activity against various planktonic organisms, however data is limited on efficacy, and few studies have been performed on biofilms. Objectives: We sought to investigate the antibacterial activity of acetic acid against important burn wound colonising organisms growing planktonically and as biofilms. Methods: Laboratory experiments were performed to test the ability of acetic acid to inhibit growth of pathogens, inhibit the formation of biofilms, and eradicate pre-formed biofilms. Results: Twenty-nine isolates of common wound-infecting pathogens were tested. Acetic acid was antibacterial against planktonic growth, with an minimum inhibitory concentration of 0.16-0.31% for all isolates, and was also able to prevent formation of biofilms (at 0.31 %). Eradication of mature biofilms was observed for all isolates after three hours of exposure. Conclusions: This study provides evidence that acetic acid can inhibit growth of key burn wound pathogens when used at very dilute concentrations. Owing to current concerns of the reducing efficacy of systemic antibiotics, this novel biocide application offers great promise as a cheap and effective measure to treat infections in burns patients

Friction reduction and zero wear for 52100 bearing steel by high‐dose implantation of carbon

Ion implantation of carbon in the AISI 52100 bearing steel yields a distinct reduction in friction and wear. This improvement is strongly dependent on the implanted fluence. The coefficient of friction decreases from 0.6 to 0.2 for doses >1×1018 cm-2 (energy 100 keV) and a wear reduction to nearly ‘‘zero wear’’ was obtainable even under severe wear conditions. The counterpart (unimplanted AISI 52100 steel ball) shows a similar behavior, which demonstrates that the tribological system is totally changed. Mössbauer spectroscopy and x-ray diffraction revealed that hexagonal ¿-carbide is formed on implantation. On the other hand, Rutherford backscattering spectrometry shows that for high doses a large fraction of the implanted carbon is not contained in this carbide

3D simulation of sputter deposition of titanium layers in contact holes with high aspect ratios

A 3D simulation program has been developed which is capable of simulating layer deposition on 3D topography features such as high aspect ratio contact holes. In this paper we investigate the sputter deposition of Ti which, after rapid thermal nitridation (RTN), serves as a barrier layer for subsequent contact hole filling. The low bottom coverage of the sputter deposited layers in contact holes is well predicted by the simulations. Simulations were carried out for a range of different contact hole aspect ratios and good agreement with measured bottom coverage data available from literature was obtained. As the bottom coverage values are essential for assessing the electrical properties of the contact after filling by blanket tungsten, the simulations are very useful for investigating different shapes of contact holes and vias. The simulator is part of a multidimensional process simulation system and part of a topography simulator for optical lithography, dry-etching, and layer depositi on. A result of the simulation of a topography process sequence, leading to a tungsten plug in a contact hole is shown

Three-dimensional simulation of ionized metal plasma vapor deposition

A physically based model for full three-dimensional(3D)feature-scale simulation of ionized metal plasma (IMP) deposition has been implemented. It assumes a dynamical equilibrium of particle fluxes where the sum of delivering (positive ) and consuming (negative) fluxes is zero. This allows to calculate the de position rates of metal at the different positions on the feature surface. The simulator is validated by considering the quasi-2D case of a long trench and comparing the results with data from the literature. Vias are investigated by compar ing the profiles to the results for long trenches. Finally, the application to 3D structures without any symmetry is shown

Local material removal by focused ion beam milling and etching

Focused ion beam (FIB) have drawn considerable interest as a tool for micromachining in the sub-micrometer regime with major applications in failure analysis and circuit repair. With shrinking dimensions, the demands on the precision of FIB-machining are increasing. In this article, focused ion beam enhanced etching of silicon is investigated using iodine as an etchant which leads to an increase in the material removal rate of silicon by a factor of up to 30 compared to sputter erosion. The influence of current density, dwell time, and loop time on the removal rate is discussed and compared to model calculations. By secondary electron microscopy, the maximum slope of the generated structures has been determined. Finally, the application of this technique to the formation of thin lamellas for TEM inspection is shown

Tetramethoxysilane as a precursor for focused ion beam and electron beam assisted insulator (SiO(x)) deposition

Focused ion beams are intensively used for device modification by local material removal and ion beam induced metal deposition. With shrinking dimensions on modern multilayer devices, the need for ion beam induced insulator deposition is increasing. In this article, tetramethoxysilane as a precursor for ion beam induced deposition has been investigated. The influence of beam parameters dwell time and loop time on the material deposition rate will be discussed and compared to model calculations. For optimized scanning conditions, a maximum deposition rate of 0.33 mu m3/nC was found. Insulating films were also deposited using an electron beam. The chemical composition and electrical properties of these films were compared with the films deposited by the ion beam. For electron beam deposition, the resistivity of the deposited films was 1 X 10(exp 6) ohm cm which is two orders of magnitude higher than for ion beam deposited film