C-312 R2R Metal Strip Coating - PVD Deposition and Applications (half day)
This new SVC Tutorial is explicitly focused on the engineering and production of roll-to-roll metal strip coatings using industry proven, highly productive physical vapor deposition (PVD) techniques such as magnetron sputtering and electron beam (EB) evaporation. The Tutorial will also review the related metrology for in situ thin film process quality management.
Typically, large area thin film coating applications utilize glass substrates for architectural glazing or photovoltaic manufacturing. Mass production for coatings on flexible substrate materials are primarily based on polymer films, which are R2R deposited by similar PVD techniques, for use in display, packaging, or barrier applications.
Based on these widely accepted thin film solutions, this tutorial will highlight industrial vacuum coatings on aluminum, copper, or stainless steel strip for high performance optical layer stacks. The key applications for these coatings are enhanced specular surface reflectors for the lighting industry and solar light absorbing films for solar thermal collectors.
To develop sufficient productivity for such functional PVD coatings on metal strip, this tutorial provides an overview regarding air-to-air manufacturing techniques for R2R handling of heavy weight metal coils at a substrate speed of approximately 20 m/min.
The basic features for thin film deposition using EB evaporation and rotatable magnetron sputtering are explained. These techniques are compared as to their performance for high rate deposition of high and low index oxide coatings as well as for metallization.
Furthermore, the prerequisite cleaning and outgassing of a continuously moving metal surface by applying tailored and efficient recipes for plasma pretreatment are reviewed in detail.
Metrology is important for process monitoring and is the final segment of this comprehensive tutorial. Techniques and features for in situ measurement of reflectance, spectroscopic ellipsometry to evaluate refractive index n, extinction coefficient k, film thickness, and XRF measurements are reviewed.
This half day tutorial is targeted to R&D personal, operators, and managers who are interested in the industrial scale, continuous operation of PVD coatings on metal strip.Course Details:
This short tutorial is recommended for production engineers, operators, technicians and R&D personal, who develop and operate reactive magnetron sputtering processes with both planar and rotatable cathodes. The industrial application of such processes in production lines is mainly related to large area glass and web coatings. Reactive magnetron sputtering is important for deposition of optical multilayers of oxides, nitrides, and other compound films using metallic targets. The application of process control for conductive oxide targets is also considered. The requirements for highest productivity demand fast feedback control loops to overcome inevitable hysteresis effects. The application of such actively controlled reactive sputter processes allows for beneficial usage of transition mode. This results in higher yield, long-term stable deposition rates, excellent film uniformity and selected stoichiometry to ensure customized or specified film properties.
This short tutorial explains the operation principles for reactive magnetron sputtering valid in both DC and AC mode. The appearance and restrictions of hysteresis effects for reactive sputtering of different oxides is considered. Due to competing effects of oxygen partial pressure versus power density at the target the deposition rate drops down drastically while increasing the oxygen gas flow rate. Limitations of mass flow controlled reactive gas inlet are explained with respect to both deposition rates and film properties.
Optical emission spectroscopy is the universal and appropriate method for characterization of reactive sputter processes. The intensity of a spectral line of the sputtered target material can be easily measured and it represents the deposition rate. The actively controlled inlet of reactive gas flow rate keeps that parameter constant. Therefore the basic interaction of reactive gas flow, partial pressure, and sputter rate is demonstrated for reactive sputtering of TiO2. With respect to sputtering within transition versus reactive mode a classification of relevant working points is presented for compound materials like SiO2, TiO2, Nb2O5, SnO2, ITO, ZnO:Al, Si3N4.
The Plasma Emission Monitor is an appropriated tool to actively control such reactive sputter processes resulting in higher yield. A detailed comparison of features of conventional MFC control versus superior PEM control highlights such benefits in mass production by achieving higher rates at least of a factor 3.
A survey and detailed description of a variety of other techniques or related tools like acoustic optical spectrometer, mass spectrometer or lambda gas sensors is presented. Another appropriated technique measures the voltage-current characteristics while sputtering oxide materials like SiO2. At a given constant power the discharge voltage represents the oxidation of growing silica films. Therefore the method of impedance control keeps the deposition rate constant by dosed oxygen gas flow rate, which is referenced to the magnetron voltage.
Film thickness uniformity control is successfully applied for long or extended magnetron sputter sources. Industrial approved and reliable technical solutions are demonstrated in large area glass and web coaters. Such important features are magnetron setup, power supplies, and fast response gas distribution manifolds applied. Results with regard to both film properties and dynamic deposition rates of oxide and nitride films are presented. An extended time is scheduled for intensive discussion of your relevant practical issues.Instructor: Johannes Strümpfel, VON ARDENNE Anlagentechnik GmbH - Germany
graduated with a PhD in physics and works as Lead Technologist at VON ARDENNE in Dresden. He is a distinguished expert developing optical layer stacks and the related metrology for large area coatings on glass, metal strip and polymer films. His valuable industrial experience operating production coaters, will beneficially contribute to this tutorial. Dr. Pröhl’s expertise is focused on actual thin film applications using both high rate rotatable magnetrons and evaporation systems with EB-guns.
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