Magnesium fluoride is an ultraviolet (UV) transparent material which is widely used in optical applications over a wide wavelength range. We have developed a novel atomic layer deposition (ALD) process for depositing magnesium fluoride thin films for the first time. MgF2 films were grown at 250-400 degrees C using Mg( thd)(2) and TiF4 as precursors. The crystallinity, morphology, composition, thicknesses and refractive indices of the films were analyzed by X-ray diffraction/ reflection ( XRD/XRR), transmission electron microscopy ( TEM), atomic force microscopy ( AFM), field emission scanning electron microscopy ( FESEM), time-of-flight elastic recoil detection analysis ( TOF-ERDA), and UV-vis spectrophotometry. Electrical properties were also measured. The growth rate was temperature dependent decreasing from 1.6 A cycle 21 at 250 degrees C to 0.7 angstrom cycle(-1) at 400 degrees C. The films were polycrystalline at 250 - 400 degrees C. The refractive indices were between 1.34 - 1.42 and the permittivity 4.9. The impurity levels were below 0.6 at.% in the films deposited at 350 - 400 degrees C

Material mixtures offer new possibilities for synthesizing coating materials with tailored optical and mechanical properties. We present experimental results on mixtures of HfO2, ZrO2, and Al2O3, pursuing applications in UV coating technology, while the mixtures are prepared by magnetron sputtering, ion beam sputtering, plasma ion-assisted deposition (PIAD), and electron beam evaporation without assistance. The properties investigated include the refractive index, optical gap, thermal shift, and mechanical stress. The first high reflectors for UV applications have been deposited by PIAD.

A novel atomic layer deposition process for the preparation of fluoride thin films in a temperature range of 225 degrees C-400 degrees C is introduced. The crystallinity, morphology, composition, thicknesses, refractive indices, and transmittance of the films are analyzed. Low impurity levels are obtained at 350 degrees C-400 degrees C with good stoichiometry. Refractive indices of 1.34-1.42 for MgF(2), 1.43 for CaF(2), and 1.57-1.61 for LaF(3) films are obtained.

Ion-beam-sputtering (IBS) single-layer and multilayer coating designs for UV applications were examined after the deposition process as well as after a defined postdeposition treatment. High internal compressive film stress as well as moderate absorption losses in the UV spectral range were measured at the as-deposited thin films. Due to a controlled postdeposition treatment process, the absorption losses and the high compressive stress can be reduced significantly. We show that the remaining thin-film stress of SiO2 and HfO2 multilayer designs can be specifically manipulated by the parameters of the postdeposition treatment. Even zero and tensile stress can be achieved for complex multilayer coatings.

LaF(3) thin films of different thicknesses were deposited on CaF(2) (111) and silicon substrates at a relatively low substrate temperature of 150 degrees C. Optical (transmittance, reflectance, refractive index, and extinction coefficient) and mechanical (morphology and crystalline structure) properties have been investigated and are discussed. It is shown that LaF(3) thin films deposited on CaF(2) (111) substrates are monocrystalline and have a bulklike dense structure. Furthermore, it is presented that low-loss LaF(3) thin films can be deposited not only by boat evaporation but also by electron beam evaporation.

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We realized metal fluoride coatings with a high packing density and a low extinction coefficient by plasma (ion)-assisted deposition. The densification can be performed by different types of plasma sources, e.g., by a Leybold LION source and a Leybold APSpro, respectively. But the as-deposited coatings show a characteristic absorption behavior, whereas the absorption losses can be reduced in a postdeposition UV treatment step. We show experimental results of the plasma-assisted metal fluorides before and after the UV treatment and present a new model that allows us to describe and calculate the characteristic absorption losses of LaF3, MgF2, and AlF3.

ArF lithography technology requires minimization of optical losses due to scattering and absorption. Consequently, it is necessary to optimize the coating process of metal fluorides. The properties of metal fluoride thin films are mainly affected by the deposition methods, their parameters (temperature and deposition rate) and the vacuum conditions. A substrate temperature of more than 300°C is a condition for high density and low water content of metal fluorides. Therefore, a substrate temperature of 150°C results in inhomogeneous films with high water content. Until now, the best results were achieved by boat evaporation. This paper will demonstrate that most of the common metal fluorides like MgF2, AlF3, and even LaF 3 can be deposited by electron beam evaporation. In comparison to other deposition methods, the prepared thin films have the lowest absorption in the VUV spectral range. Furthermore, metal fluoride thin films were prepared by ion assistance. It will be d emonstrated, that they have less water content, high packing density, and low absorption in the VUV spectral range. In this study, single layers of LaF3 and AlF3 and antireflection coatings were prepared by electron beam evaporation with and without ion-assistance. The mechanical, structural, and optical properties were examined and discussed