Innovations in Surface Coatings and Treatments

Wednesday, May 2, 2001 1:30 PM in Room Town & Country

Start Invited? Item
1:30 PM G1-1-1 Control of Ionization in Magnetron Sputtering:fromCathode Design to Film Properties
J. Vyskocil, J. Valter (HVM Plasma Ltd., Czech Republic)
Magnetron sputtering with enhanced ionization becomes widely used in many applications. Ion bombardment of sputtered film can be increased by external source (electron beam, RF or microvawes) or by magnetron plasma confinement in target -substrate space. Plasma parameters of magnetron discharge measured near substrate surface in laboratory and industrial coating systems are reported. The effect of magnetron design,e.g. magnetic system with permanet magnets and electromagnetic coil, strength of magnetic field of balanced and unbalanced magnetron, anode design etc., on substrate ion current density is demonstrated. The results of magnetic field modelling by finite element method are compared with measurement and used for basic model of plasma confinement. The role of ionization on thin film growth is illustrated on properties of hard coatings prepared by unbalanced magnetron sputtering under different ion-to-neutral ratio of particle flux to substrate surface.
2:10 PM G1-1-3 Ensuring Long Term Stability of Process and Film Parameters During Target Lifetime in Reactive Magnetron Sputtering
H. Bartzsch, P. Frach, K. Goedicke (Fraunhofer-Institut Elektronenstrahl und Plasmatechnik, Germany); B. Boecher (Fraunhofer-Institut Elektronenstrahl und Plasmatechnik)
Reactive magnetron sputtering of a metallic target in a mixture of inert and reactive gas is now widely applied for compound deposition at high rates. It has been shown that problems due to arcing and the hysteresis of the process can be overcome by pulse sputtering and appropriate process control. Another important aspect is the shift of deposition parameters and reactive working point due to the target erosion. For industrial application compensation of the shift is desired to achieve constant deposition conditions and homogeneous film properties during target life. For this different possibilities exist. In the paper reactive sputtering of alumina films using stationary sputtering with the Double Ring Magnetron (DRM) is reported. Ongoing target erosion is compensated by using the movable magnet systems of the DRM to keep magnetic field strength at the target constant during target erosion. This technique has the advantage of constant electric discharge parameters during target life and therefore ensures constant energetic substrate bombardment. Results with respect to constancy of deposition rate, film thickness distribution and film properties are discussed. Furthermore process stability and efficacy of the hidden anode are evaluated throughout target life.
2:30 PM G1-1-4 Automated Reactive Sputtering
W.D. Sproul, B.E. Sylvia, S.M. Wilhelm (Reactive Sputtering, Inc.)
Reactive sputtering is a balancing act. The goal is to produce a compound of known stoichiometry at the substrate from the reaction of the sputtered material with the reactive gas. However there should be no debilitating reactions occurring at other places in the chamber such as on the target surface. Partial pressure control of the reactive gas allows this goal to be met in contrast with other techniques such as mass flow control that invariably lead to poisoning of the target and loss of deposition rate. A new reactive process control (RPC) system is now available with a nested loop for the control of the reactive gas partial pressure. It provides real-time adjustment of the process variables in response to changes in the operating conditions. The RPC also has automated features for calibration of the reactive gas partial pressure and generation of hysteresis plots. Up to two gases gas be controlled concurrently, and if desired off-stoichiometric films can easily be deposited. These RPC features lead to highly reproducible reactive sputtering processes with the highest rates possible for the compound. The operation of the new RPC will be described along with results for the reactive sputtering of aluminum in argon/oxygen and argon/oxygen/nitrogen atmospheres.
2:50 PM G1-1-5 Industrial Precision Deposition by Filtered High Current Arc
P. Siemroth (Fraunhofer Institute for Materials and Beam Technology, Germany); W. Hentsch (FHR Anlagenbau GmbH Ottendorf-Okrilla, Germany); H.H. Schneider, H. Hilgers (IBM Germany, Mainz, Germany); J. Berthold (Fraunhofer Institute for Material and Beam Technology Dresden, Germany); T. Schülke (Fraunhofer USA)
In different industries, an increasing demand can be observed for different kinds of precision deposition. This field includes both ultra thin films on micro objects and deposition on microstructures. An important application of ultra thin protective films is the topcoat on hard disks. In order to increase the storage density, the head-to-media spacing as well as the thickness of the overcoat has been reduced continuously. Until now, the thickness of the sputtered CNx films was reduced to about 7 nm. The limit for this technology seems to be achieved. For further progress a new technology is needed. Filtered arc deposition is one of the most promising candidates for the deposition of thinner films - down to 2 ... 3 nm with an even improved mechanical resistance. Ultra thin coatings deposited by filtered high current vacuum arc show promising functional properties required for future protective films in magnetic hard disk drives. Another application area is the manufacturing of metallic lines and interconnections with high aspect ratios in the deep sub-micron region in microelectronics. Test depositions with laboratory scale devices, carried out by different groups, have shown that trenches with a width below 300nm and an aspect ratio over 3 can be void free filled. High purity and a defect free microstructure are observed. The industrial demands, illustrated by the examples stimulated developments of more compact and higher productive filtered arc sources integrable into complex systems. Focusing on hard disk overcoats and copper metallization in microelectronics, the paper presents the current stage of development of industrial filtered arc technology and its introduction into manufacturing.
3:10 PM G1-1-6 An Effective Way to Improve the Coated Tool Performance Through Annealing
K.-D. Bouzakis, N. Michailidis ( Aristoteles University of Thessaloniki, Greece); G. Erkens (CemeCon GmbH, Germany)
PVD coated tools were examined in turning at various cutting speeds, keeping all the other operating parameters constant. After thorough SEM investigations and EDX analyses of the cutting wedge at various cutting stages, an enhanced behavior as far as the first coating failure is concerned, at a cutting speed value of 200 m/min in comparison to cutting speeds of 100 and 300 m/min was observed. That was a significant indication that temperature dependent phenomena are activated, influencing the coating wear behavior. @paragraph@ In order to investigate the aforementioned cutting temperature dependent phenomena, coated tools were annealed at various temperatures. The annealed coated tools were tested in milling operation and the SEM investigations, the EDX analysis and the FEM simulation of the cutting edge revealed an improved coating performance in milling, in the case of the annealed specimen at 400°C. @paragraph@ To elucidate these results concerning the improved specimen performance, the coating material properties and more specifically the stress strain curves after various annealing temperatures were extracted by means of a developed evaluation procedure in the Laboratory for Machine Tools and Manufacturing Engineering of the Aristoteles University of Thessaloniki. The annealed coated specimen at 400°C was found to have enhanced material properties according to the determined coating constitutive law in comparison to the other annealing temperatures and the as deposited coating as well.
3:30 PM G1-1-7 Improvement of PVD Coated Inserts Cutting Performance, Through Appropriate Tool Pre- and Post-Treatments
K.-D. Bouzakis, N. Michailidis, K. Efstathiou, S. Hadjiyiannis (Aristoteles University of Thessaloniki, Greece); G. Erkens, S. Rambadt, I. Wirth (CemeCon GmbH, Germany)
The fatigue and the wear behaviour of coatings on cemented carbide (HM) and high speed steel (HSS) substrates with different surface treatments are investigated experimentally in milling and in impact testing and analytically through a Finite Elements Method (FEM) simulation of the cutting and impact test process respectively. Substrate pre-treatments such as polishing, mikro-blasting, glass-blasting and coating post-treatments, as for instance mikro-finishing, edge polishing etc, are some of the investigated surface treatments. @paragraph@ The initiation and progress of the tool failure is depicted through Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray microspectral investigations of the used cutting edges. Furthermore the FEM simulation of the contact between the tool and the workpiece enables a quantitative description of the influence of the substrate and coating surface integrities and of the occurring mechanical stress components on the coating failure. Hereby, the coating fatigue endurance and experimentally derived technological cutting data were considered. Coating and substrate constitutive laws are also taken into account in the FEM simulations. @paragraph@ The obtained experimental and computational results exhibit quantitatively the influence of substrate pre-treatment as well as the coating surface post-treatment on the cutting performance.
3:50 PM G1-1-8 Optimisation and Characterisation of a TCP Type RF Broad Beam Ion Source
M.Z. Zeuner, F.S. Scholze (IOT - Innovative Oberflaechentechnologien GmbH, Germany); H.N. Neumann (Institut fuer Oberflaechenmodifizierung e.V., Germany)
A TCP (Transformer Coupled Plasma) type broad beam ion source is developed and optimised according to the beam parameters and the energy transfer to the discharge plasma. A TCP type plasma excitation is known to be a very effective excitation principle providing for simultaneously high plasma densities and high degrees of dissociation. However, an unwanted capacitively coupling of the RF voltage at the primary RF coil may cause an RF modulation of the plasma potential. Optimising the setup and geometry of our RF excited broad beam ion source we applied a global discharge model including a transformer like and a capacitively coupling of the primary coil to the discharge plasma. The model allows to calculate an optimised discharge geometry which delivers a desired beam current at simultaneously low RF power and source erosion. The resulting beam parameters are proofed by beam profile measurements and analysis of the beam composition and the energy distribution of the species. Especially the examination of the energy distribution of different ions is helpful to understand the RF power coupling to the discharge. The energy distribution is mainly formed by the beam potential applied to the screen grid. But it provides additional information on the time modulation of the plasma po-tential and hence on the RF power coupling to the discharge. Beside of the energy distribution the beam composition is characteristically affected by the power coupling and the resulting chemical reactions in the discharge vessel with source components and with the grid system.
4:10 PM G1-1-9 Ion Density Studies in Vacuum Arc Plasmas Passing Through an Off-Plane Double Bend Magnetic Filter
G.F. You, B.K. Tay (Nanyang Technological University, Singapore)
An off-plane double bend (OPDB) magnetic filter is used to remove macroparticles from the plasma beam of cathodic vacuum arcs, making it suitable for the preparation of high quality thin film. The investigation of carbon ion motion in the filtering magnetic field had been reported before. Recently the filtered cathodic vacuum arc (FCVA) technology have been explored to deposit thin copper films as another possible technique besides the sputtering and the electron plating depositions. In this work, We will report on the plasma transportation of Cu ions in an OPDB FCVA system. The density of multiple-charged copper ions has been measured by Langmuir probe under the influence of different magnetic field and arc current. The experiment results are compared to the correspondent simulation results based on a modified drift-collision model.
4:30 PM G1-1-10 Room Temperature Deposition of High-Purity Silicon Oxide Films by rf Plasma-Enhanced CVD
K Teshima (Nagoya University & Dai Nippon Printing Co.Ltd.,Japan); Y. Inoue, H. Sugimura, O. Takai (Nagoya University, Japan)
The purpose of this study is to determine the deposition conditions to make high-purity silicon oxide films at low substrate temperatures near room temperature by inductively-coupled rf plasma-enhanced CVD. The effects of rf power and substrate position on the film composition were studied. We used a mixture of tetramethoxysilane and oxygen as a source gas. In order to obtain carbon-free silicon oxide films, the substrate temperature was kept slightly higher than the wall temperature during the deposition. The chemical compositions and bonding states of the deposited films were evaluated with Fourier transform infrared spectroscopy (FTIR). @paragraph@ First the rf power was varied from 50 to 300 W. FTIR analyses clearly demonstrated that the absorption bands due to OH groups were reduced markedly when the rf power increased from 50 to 300 W. At the rf power of 300 W, the absorption bands almost disappeared. The composition of the film deposited at 300 W almost corresponded with that of pure silicon oxide films prepared by thermal oxidation. In addition, a pure silicon oxide film was prepared at the substrate temperature of 50°C. @paragraph@ Next we investigated the effect of the substrate position on the film composition. A decrease in OH groups in the deposited films was observed with closing the distance between the center of the inductively-coupled coil and the substrate position when the substrate was located at the upstream position from the coil. The optimum substrate position was 300 mm upstream from the coil. When the distance was shorter than 300 mm, the deposition rate was very small or no film was deposited.