Papers

ICMCTF2007 Session G5: Large Area Production Coatings, Plasma Cleaning and Pre-Treatment of Large Surfaces

Monday, April 23, 2007 1:30 PM in Room Royal Palm 4-6

Monday Afternoon

Start	Invited?	Item
1:30 PM		G5-1 Status of Industrial PVD on Metal Strips for Optical Purposes D. Peros, H. Kuester (Alanod Aluminium-Veredlung GmbH & Co. KG, Germany) Roll to roll large area PVD (Physical Vapour Deposition) on metal strips is a well established process. This work reports about optical multilayer systems deposited onto aluminium and copper strips. The coatings are used either for reflective or absorbing purposes. The depositions are done in air-to-air continuously operated vacuum lines with speeds up to 25m/min and coil width of 1250mm. Coating conditions as well as process control will be discussed. In situ layer thickness monitoring via ellipsometry gives a high process stability. High repetition reflectance measurements are also used to determine the final product quality. Prior to the deposition, different pre-treatments can be applied on the substrate e.g. DC- or MF- glow discharge or sputter etching. The pre-treatment depends on the type of the substrate and is necessary to achieve a high adhesion of the coating. Sputtering and electron beam evaporation are the processes used for the layer deposition. For certain layers these processes are driven in the reactive modus. Some properties of graded cermets used as solar absorbers will be presented.
2:10 PM		G5-3 Sputter Processes for Large Area Coating - Examples of Current Developments G. Braeuer (Fraunhofer Institutes FEP & IST, Germany); T. Jung (Fraunhofer-Institute IST, Germany); V. Kirchhoff, E. Schultheiß (Fraunhofer Institutes FEP & IST, Germany); B. Szyszka (Fraunhofer-Institute IST, Germany) High volume plasma discharges nowadays are the key for economic deposition of thin films on plane (e.g. glass sheets) or shaped substrates. During the past 30 years plasma based physical and chemical vapor deposition processes have established in numerous fields of applications. Pulsed plasma plays an important role in research and industry since about 15 years. Pulse magnetron sputtering has opened the door for long term stable and high rate deposition of insulating materials on large areas. High Power Impulse Magnetron Sputtering (HIPIMS) is the key to very high plasma densities (ionization degree around 0.5) and thus improved film structures. Current research work also focuses on the use of gas flow sputtering for applications like thermal barrier coatings or transparent scratch resistant films on plastics. Such sputter sources are rather simple and can be easily scaled up. In this contribution we will report on above-mentioned and further examples of current research on sputter processes for large area coatings.
2:30 PM		G5-4 Electro-Magnetic Levitation: A New Technology for High Rate Physical Vapour Deposition of Coatings onto Metallic Strip L. Baptiste, G. Gleijm, N. van Landschoo (Corus Research, Netherlands); J. Priede (Coventry University, United Kingdom); J.S. van Westrum (CP3 Metrec B.V., Netherlands) Since about 3 decennia, there is a growing interest from the strip coating business for fully continuous or semi-continuous PVD based coating processes. The development of such processes however, dates back to the early sixties. For the deposition of thin coatings (~<100 nm) on polymer webs and thin metal foils, magnetron sputtering has become the predominant technology. However, the deposition rate obtained with magnetron sputtering is too low to be economically interesting for the metal sheet and strip businesses. Here the high rate Electron Beam (EB) PVD, seems to become the state of the art technology, probably together with Jet Vapour Deposition for the low boiling point (high vapour pressure) metals like zinc and magnesium. Recently, Corus has developed a novel PVD process principle, which may alleviate some of the disadvantages of both EB PVD and JVD and should combine the advantages of both. The process is based on the well-known technology of levitation of conductive materials in high frequency electro-magnetic fields. By proper coil design high power densities can be achieved and metals like aluminium, nickel and copper can easily be evaporated. The vapour produced can be guided to the substrate by a properly designed duct system, which achieves excellent coating uniformity and a very high vapour utilisation. The concept of this technology and some of the experimental results so far will be presented. Further up-scaling of this technology should demonstrate the technical and economical feasibility for application in the metal strip coating business. However it may also find very valuable applications in other fields of PVD coating e.g. in coating of non flat surfaces.
2:50 PM		G5-5 Utilization of Cold-Cathode EB Guns for High-Rate PVD - State of the Art and Future Perspectives G. Mattausch, F.H. Roegner, P. Feinaeugle, R. Bartel (Fraunhofer Institute FEP Dresden, Germany) Electron Beams are known to be powerful and versatile tools for evaporation of various kinds of materials. At the other hand, conventional high-power electron beam sources based upon thermionic emitters are expensive and therefore in many PVD processes not applicable because of economic considerations. To overcome this dilemma, we have developed a cost-efficient EB system which combines an axial-type, cold-cathode EB gun with a MF high-voltage power supply. Inside the EB gun, a high-voltage glow discharge is sustained. The ion bombardment of the cathode delivers secondary electrons which can be accelerated across the plasma sheaths and which then form the beam. This beam source is compact, light-weight, requires minimum cooling, is easy to maintain and does not need differential pumping. Process interruptions due to high-voltage breakdowns are kept below 2 ms by the fast arc handling electronics implemented in the power supply. We will demonstrate the features of cold-cathode technology by introducing a special 30 kV / 60 kW package which was recently created and applied for depositing thick copper layers onto plastic substrates. To further improve the economic data of the coating process and to minimize the thermal substrate load, the copper was evaporated from a graphite block which was covered by a thermally isolating plate with a shaped vapour aperture. The vapour aperture is dimensioned such that vapour particles directed to the substrate can pass and build up the desired copper layer. Those parts of the vapour stream, however, which are not directed to the substrate and which would eventually form wild coatings inside the deposition chamber are blocked by the cover, condense into the liquid state and drip back into the crucible. In this way, utilization of the evaporation material is markedly enhanced. At the same time, the cover reduces the heat radiation from the melt pool and also the amount of backscattered electrons hitting the substrate.
3:10 PM		G5-6 In-Line Analyzing of Layers with High Precision by X-Ray Fluorescence J. Piltz (Amtec GmbH, Germany) The effective control of coating processes requires to ascertain precise online information on the current coating thickness and the stoichiometry. New instruments for energy dispersive X-ray fluorescence analysis (EDXRF) allow to measure single-, multi- or alloy layers in the thickness range from 20 nm to 50 µm on different substrates (metal, plastics). Some design rules of the X-ray line will be discussed to increase the measuring effect and the reproducibility of measuring values. Observing the condition of a real coating process is important to guarantee the measuring parameters over the whole operation period. A special protection system for each measuring unit against the process influences has to build up. Some typical measuring jobs will be presented and the measuring results will be discussed.
3:30 PM		G5-7 Large Area PVD Coating of Metal Strips and Sheets - New Trends and Developments in Europe Chr. Metzner (Fraunhofer Institute FEP Dresden, Germany) World wide activities for the introduction of vacuum coating in the field of surface finishing of metal strips and sheets are steadily growing. The applications are wide diversified from corrosion protection coatings e.g. for car bodies via abrasion protection layers up to optical layer stacks onto large metal surfaces. Based on new developments for PVD coating technologies and techniques especially high value products are coming more and more in the focus. In the last years our institute and European companies have developed new technologies and new layer systems for different applications. The paper gives an overview about these activities. Great progress was reached concerning our plasma activated high-rate electron beam deposition by the so called SAD and HAD processes. It was possible to develop basics for an active cooling of metal strips and sheets during the PVD coating. A continuous challenge is the process stability and the quality assurance during long term deposition. We have started new developments to solve this problem with In-situ Advanced Process Control (APC). The investigations concerning new layer stacks reach from hard coatings via transparent abrasion and scratch resistant layers up to selective solar absorbing films. The new process technologies and available equipment's are depicted. The paper gives an overview about new trends and developments in large area PVD coating of metal strips in Europe.
3:50 PM		G5-8 Study of 2 inch Al₂O₃ Substrate's Pattern by Imprinting Process H.H. Kim, S.K. Yang, S.G. Lee, B.H. O, E.L. Lee, S.G. Park (Inha University, Korea) This study is about Al₂O₃'s process that becomes patterning in LED (Light Emitting Diode) fabrication that do based on GaN (Gallium Nitride). LED that do based on GaN is a lot of studies present, and do developments. Among them, high efficiency of Light Emitting Diode and development of function are point research content. We offered research for PSS (Patterned Sapphire Substrate) by method that can heighten efficiency among this study fields. Substrate which is epitaxy is used to set Lattice Constant using Al₂O₃, and done part is doing to do growth by Al₂O₃ board that become patterning because remain through mismatch of V with GaN. Also, PSS has characteristic that is emitted light to all directions have direction and heightens efficiency. In most industry, PSS process uses photoresist by mask material to be done and Al₂O₃ is doing etching. Material based Al₂O₃ is using 2 inches. However, to wafer that become 2 inches, photoresist forms when do patterning 3um circular cylinder by region each differ. These problem is transcribed almost as it is patterning shape by 1:1 etch rate of PR and Al₂O₃. So, pattern must become patterning by all same shape on 1 wafer. However, height or shape differs much on 1 chapter's wafer by various problems. Therefore, when did etching, PSS's yield rate do drops much. We use Imprinting technology that has been getting into the spotlight recently to solve these problems and mask material did patterning. Imprinting uses Mold and did patterning evenly to 2 inches wafer. Our research will become data that is good for industries that is manufacturing LED chip.