Optisch dünne Schichten aus Sicht eines Anwenders

Optical thin films are used for example, in precision optics. Their effect is important for lenses with many elements. In special plants, materials are evaporated in order to deposit to a thin film on substrates. Cleaning before and smoothing after deposition are also steps in thin film production. Because of its advantages, ion-assisted deposition of cold substrates overcomes conventional physical vapour deposition of heated substrates.     

Steuerung der Benetzungseigenschaften von optisch transparenten Polymeren durch Antireflexstrukturen und dünne Schichten

Controlled wetting of optical polymers by antireflective structures and thin films The wetting behaviour of antireflective structures can be modified by additional coatings to become superhydrophobic or hydrophilic. The sub‐wavelength structures which increase the samples transmission are generated by plasma etching. Bump structures with large aspect ratio show a Lotus‐like behaviour immediately after coating with a thin hydrophobic layer. In case of PMMA the Lotus‐state can only be achieved if a thin silica layer is arranged below the hydrophobic top‐layer.     

Nanostrukturierte dünne Schichten mit Giant Magnetoresistance (GMR) Effekt für Sensoranwendungen

Nanostructured Thin Films with Giant Magnetoresistance (GMR) Effect for Sensor Applications The basics of the Giant Magnetoresistance (GMR) effect in thin films prepared by evaporation in ultra high vacuum or by sputtering are explained and different GMR‐systems are presented. Applications of the GMR and the related TMR (Tunneling MR) effect can be found in sensor applications as well as in information and data storage technology.     

Dünne Schichten durch Deposition unter streifenden Einfall

Micro‐ and nanostructured thin films by Glancing angle deposition Physical vapour deposition under conditions of obliquely incident flux and limited adatom diffusion results in films with a columnar microstructure. These columns will be oriented toward the vapour source. An additional substrate rotation can be used to sculpt the columns into various morphologies (slanted and vertical posts, chevrons, screws or spirals). With this glancing angle deposition (GLAD) technique can prepared porous thin films with engineered structures from a variety of dielectric, semiconducting and metallic materials. The paper presents the In this paper the physical fundamentals of the GLAD technique are introduced, the production of micro‐ and nanostructures of different morphology on non‐patterned and patterned substrates is demonstrated and some possible applications of this new deposition technique are introduced.     

Stofftransport durch Schichtsysteme aus Polymeren und dünnen anorganischen Schichten

Mass transport through layer systems consisting of polymers and thin inorganic layers Flexible layer systems from polymeric substrates, thin inorganic layers deposited by vacuum coating and additional polymeric layers are frequently in use to obtain high barrier properties, predominantly against oxygen and water vapour. Especially in cases where additional polymeric coatings are able to fill defects in the inorganic layers, barrier properties of the resulting layer systems show a stronger dependence on their thickness. For the transport of condensable substances, especially of water vapour, an additional porosity in the sub‐nm‐size can be assigned to the inorganic layers. This, however, has a negligible effect on gas permeation. Multilayer structures made from substrates and alternating polymeric and inorganic layers show much better barrier properties than single polymeric substrates coated with single inorganic layers. These improvements, however, are less than previously reported here. Moreover, also in these cases, the condensation of water vapour in sub‐nm pores gives much higher rates for the permeation of substances than expected from simple defect models.     

Anlagenkonzept für die Abscheidung dünner Schichten durch Plasmapolymerisation

This plasma polymer layers are deposited by a plasma enhanced CVD process directly from the gas phase of an organic precursor (plasmapolymerization). Film growth rate is limited by the quantity of gas input. Plasmachemical conversion in the gas phase as well as at the film surface can be applied to affect film properties. The relation between the characteristic conversion time of the process and the application features of the plasma polymer layers lead to a vacuum technological concept for development and design making large scale applications in industry very predictable.     

Plasma und Dünne Schichten

Plasma and thin films for lighting application Thin films play an important role in the lighting industry. Well known products are reflectors with simple aluminium coating or with dichroic coatings for cold light mirrors. Especially for energy saving applications special halogen bulbs are coated with a transparent hot mirror that increases the overall efficiency up to 50 % while keeping the positive properties of halogen lighting like color, color rendering index, start up performance and others unchanged. Special thin film applications realize color filters, IR filters, UV filters or color conversion filters. All these processes are vacuum processes that work with plasma assistance. The most prominent technologies for cost effective production are the PICVD processes (former development of SCHOTT AG in cooperation with Auer Lighting) and the Microdyn® technology from DSI, Santa Rosa.     

Neue Möglichkeiten zur Charakterisierung dünner Schichten mit Indentermethoden

Novel Possibilities for Thin Film Characterisation Using Indentation Methods A novel methodology for the evaluation of the response of coated substrates to mechanical contact is presented which is based on the combination of a new theoretical method and high‐accuracy indentation experiments using a spherical diamond indenter. The concept may be extended in many respects and will be illustrated here only with few special examples: Using low loads, i. e. staying completely in the elastic region, the elastic parameters of film and substrate can be measured with high accuracy. When the indentation experiments is extended until failure of the coating substrate compound, the full stress and strain fields in three dimensions in the very moment of failure can be calculated. The knowledge of those fields enables one to draw conclusions on the relevant mechanisms. Once the failure mode has been identified, layer systems with optimum resistance to that failure mechanism can be found by theoretical simulations.     

Untersuchung dünner Schichten mittels Röntgenreflektometrie

Thin film characterization by means of X‐ray reflectometry X‐ray reflectometry and diffractometry are widely used non‐destructive methods to characterize thin films in the total thickness range which is typically between 2nm and approximately 500nm. On special arrangements a resolution up to 1000nm layer thickness has been demonstrated. Layer stack morphology, surface topography, layer structure, material density, single layer or period thickness and surface and interface roughness are the typical structural parameters both of single layers and of multilayers which can be described by the measured data. The performance of the measurement setup is mainly influenced by the parameters of the incident X‐ray beam like beam divergence, monochromatism and photon energy. In the following the influence of the optical components in the beam path to angle and energy resolution of X‐ray reflectometry is discussed.     

Funktionelle Schichten auf Metallen: Maßgeschneiderte Eigenschaften durch Sol‐Gel‐Technologie

Functional Layers on Metals: Tailored Properties by Sol‐Gel Technology The value of metal articles can be substantially enhanced by convenient surface coatings. Beside organic layers (e. g. paints) and inorganic layers (e. g. enamel) wellknown as coating materials, so‐called inorganic‐organic hybrid polymers set out to combine the advantages of both coating groups. For the manufacture of such hybrid materials functional particles with sizes of a few nanometers – so‐called nanoparticles – are synthesized in the sol‐gel process. The versatility of this procedure allows to cover an extreme variety of properties of the resulting layers. Thus, depending on their composition, sol gel coatings are suited as corrosion protection, as primer, as abrasion‐reducing coating or as easy‐to‐clean layer. A sufficient wetting and adhesion on vitually any substrate can be achieved by proper choice of functional groups and pretreatment steps.     

Anforderungen und Bewertung dünner Schichten im tribologischen Einsatz

Demands and assessment of thin films in tribological applications Thin films for tribological use have been supported intensively in the last years and decades. For this reason lots of single results exist in this field of activity. But until now for engineers a handy und reliable method for the development of practical solutions is not available. The literature quoted at the end of this article deals with this problem and points out possibilities. The following paper presents selected results. Single aspects are here in this consequence only described without detailed documentation. To do this the quoted literature offers further information concerning the application of hard coatings and it refers to over 900 corresponding publications. Missing data on test parameters or boundary conditions of the test procedures as well as detailed information on all presented aspects are written down there. Tables to do selections and assessments qualify the reference as a useful handbook for the application of thin hard coatings in theory and practice. The author is pleased to help you to get the complete publication.     

Gitterkonstantenbestimmung in kubischen dünnen Schichten unter thermischer Dehnung

Lattice Constant Determination in Cubic Thin Films under Thermal Strain An X-ray diffraction procedure is presented to determine the lattice constant of a cubic thin film which is thermally strained. The procedure also gives the thermal strain. As application examples, the lattice constants of thin aluminium and copper films deposited by ion-platting are evaluated from grazing incidence diffraction data.     

In‐situ Messung dünner Schichten auf Architekturglas

For the deposition of modern coatings on architectural glass (energy‐saving, solar control, anti‐reflective), reactive magnetron sputtering plays an outstanding role. The production of these coatings by reactive sputtering requires a manufactoring equipment, that ensures high quality as well as efficient deposition of the coatings. Thin film measurement by in‐situ ellipsometry can very impressively used for monitoring and controlling the film properties, in particular in the case of more complex coatings. With regard to long‐term stability the in‐situ film measurement is of special importance with respect to the use of the novel mid‐frequency magnetron sputter technique. This technique allows the deposition rate to be increased up to 500 %, however, a dynamical plasma stabilization in the so called »transition mode« is necessary. Within the framework of a project supported by the BMBF, the spectroscopic ellipsometry was implemented on a large scale glass deposition plant (Semco Glasbeschichtung, Neubrandenburg) and was tested during the production. The investigations show that ellipsometry is outstandingly suitable for an accurate determination of the optical layer properties of coatings on architecture glass, even for complex layer systems. Therefore, the basis for an improvement of the efficiency of the plant is given.     

Keimbildung und Wachstum von TiO2 in dünnen Schichten

Nucleation and growth of TiO₂ in thin films The morphology of thin films of TiO₂ reflects the whole production process. Rutile nuclei are generated by bombardment of the growing film with particles with an energy of about 100 eV, presumably by subplantation. Anatase grows faster in amorphous films, due to lower mechanical stress. Evaporated films are metastable at room temperature and can get reproducible optical properties by postheating at the deposition temperature. The increase of the refractive index with increasing mass density cannot be described with a ClausiusMosotti approach, due to the inhomogeneous structure of the films.     

Röntgendiagnostik plasma‐gestützt abgeschiedener dünner Schichten

X‐ray diagnostics of plasma deposited thin layers Grazing incidence x‐ray diffractometry (GIXD) and x‐ray reflectometry (XR) have been introduced as well suited tools for investigations of plasma deposited thin layers. They are non‐destructive techniques, therefore a sample can be reused and measured with other techniques. A combination of GIXD and XR can give a range of interesting information about chemical, physical and crystallographic properties of thin films. Conclusions can be drawn how plasma deposition techniques and plasma parameters influence the film growth. In three examples we present the analysis of phase and chemical composition, defect structure and measurements of kinetic process parameters.