Hochleistungsplasmen zur Synthese diamantähnlicher Kohlenstoffschichten

HPPMS high‐performance plasmas for the deposition of diamond‐like carbon coatings Diamond‐like carbon (DLC) coatings Diamond‐like carbon (DLC) coatings can be used in many different applications, due to their adjustable properties like hardness as wear reduction. Regarding to the synthesis of these coatings, research is upon the High Power Pulsed/Impulse Magnetron Sputtering (HPPMS/HiPIMS), which in contrast to conventional processes like the Pulsed Laser Deposition (PLD) provides smooth coatings and therefore less postprocessing. Previous to the coating deposition in‐situ plasma analysis can be utilized to identify the process parameters. The aim relevantof this work was to identify process parameters which enable to generate a high amount and energy of carbon ions, which are required to synthesize hard DLC coatings. Regarding to the carbon ionization the promising process parameters mixture and pressure of the process gas as well as the HPPMS pulse parameters were varied. Finally, process parameters for the DLC coating deposition could be derived from these investigations.     

Verformungsverhalten nanostrukturierter HPPMS‐Hartstoffschichten

Elastic‐Plastic Deformation Behavior of Nanostructured HPPMS Hard Coatings Nitride hard coatings deposited via HPPMS (High Power Pulsed Magnetron Sputtering) or HiPIMS (High Power Impulse Magnetron Sputtering) are widely used in tribological applications due to their promising wear and corrosion resistance. During the application, the coated tools or components may be exposed to significant mechanical loads. Therefore, investigations on deformation behavior of the coatings under mechanical loading are of great importance. The objective of the present study was a comprehensive investigation on deformation behavior of nitride hard coatings from the coating system M‐Al‐O‐N (M = Cr, V) using nanoindentation und nanoscratch tests. In this regard, both nanoscale multilayer (nanolaminate) and monolayer coatings were investigated. All the coatings were deposited using HPPMS technology. Contrary to the expectations regarding a brittle behavior of ceramic‐like coatings, the results depict a considerable plastic deformation of the investigated hard coatings. Furthermore, in addition to a high strength, the applied coatings show a high crack resistance under mechanical loading.     

Wear behavior of HPPMS deposited (Ti,Al,Si)N coating under impact loading

Over the last decade the interest in High Power Pulse Magnetron Sputtering (HPPMS) and High impulse Magnetron Sputtering (HiPIMS) has undergone a considerable increase. This is mainly due to the fact that several researchers have shown that in these processes a distinct increase of the ionization of deposition species is observable. However, there is only little known about the performance of these films with regard to applications. Recently Hovsepian et al. [1] and Bobzin et al. [2] presented cutting results of different films. Both authors show that films deposited using HPPMS or HiPIMS outperform state‐of‐the‐art coatings. Depending on the cutting process, besides hardness and adhesion also excellent impact behavior is required. Therefore this work deals with the impact behavior of (Ti,Al,Si)N which was deposited using HPPMS for the application in interrupted cutting process. The impact behavior of HPPMS coating under normal and tangential loads is analyzed. During impact tests number of impacts, loads and inclination angle of the samples with regard to the load direction are varied. (Ti,Al,Si)N shows an excellent endurance even at very high loads causing Hertzian stresses in the range of 10–13 GPa. At an inclination angle of 10° and an impact load of 100 N, which corresponds to app. 10 GPa initial Hertzian stress, no damage was observed after 800×10³ impacts.     

HIPIMS: Die neue PVD‐Technologie

HIPIMS: The new PVD‐Technology HIPIMS (High Power Impulse Magnetron Sputtering) represents the most recent development in the field of PVD‐Pulse‐Sputtering‐Technology. Utilizing extreme high pulse power densities (4‐6 MW) discharge conditions are created similar to the well known arc discharge, however avoiding completely the appearance of droplets. High metal ion concentrations and multiple ionisation result in particularly dense, homogenous coatings with high adhesion to the substrate. The industrial realisation is still in embryonic state. However first HIPIMS dedicated coating equipment is available commercially. First results on CrN coatings exhibiting hardness values up to HV 3000 indicate the high potential of this new technology.     

Cross‐Magnetron‐Effekt und ITO‐Schichtabscheidung

Cross Magnetron Effect and ITO Film Deposition The large area deposition of TCO films requires a strictly homogeneous lateral distribution of the process parameters at the substrate position. In view of that, Cross Corner Effect (in case of a single magnetron source) and Cross Magnetron Effect (for dual magnetrons) can cause problems. Measurements confirm a distinct influence of these effects on the functional properties of indium tin oxide films. The effect will be discussed in terms of the concentration of the dissociated oxygen in the process gas, which depends on the plasma properties and the oxygen partial pressure.     

Ion density increase in high power twin-cathode magnetron system

In contrast to conventional plasma deposition methods, High Power Impulse Magnetron Sputtering (HIPIMS) utilizes extremely high power inputs in short pulses, providing for the discharge current densities up to several A/cm². High ion densities are observed not only during the plasma on-time, but also within the afterglow period. Once ions are generated, they can contribute to the peak ion density of the next pulse if the off-time between the pulses is sufficiently small. When the HIPIMS cycle contains two pulses, separated by a short plasma off-time and followed by a long afterglow period, the peak ion density for the second pulse can be 5-7 percents higher than for the first pulse. With a dual cathode system and time-shifted pulsing with distinct magnetron heads it was possible to increase ion density gain up to 40% for Ti targets.     

Hocheffiziente RF‐Impedanzanpassnetzwerke

Highly efficient rf impedance matching network for ICP sources Contrary to capacitive coupled plasmas (CCP) inductively coupled plasmas (ICP) offer a higher plasma density and therefore provide for higher deposition or etch rate and herewith a high efficiency for industrial low pressure plasma processes. In the following we will introduce a new impedance matching network, which was specifically developed for the requirements of the operation of inductive plasmas and especially for the use in an industrial application. For the application in production systems detailed knowledge of the plasma properties, like homogeneity and ion energy distribution is required. Plasma diagnostics and calculations of the plasma density distribution will be shown. Finally, the application in a production system, which fully automatically processes 1200 substrates of size 156 mm × 156 mm per hour on a compact 19 m² footprint, is introduced.     

Ion density increase in high power twin-cathode magnetron system

In contrast to conventional plasma deposition methods, High Power Impulse Magnetron Sputtering (HIPIMS) utilizes extremely high power inputs in short pulses, providing for the discharge current densities up to several A/cm². High ion densities are observed not only during the plasma on-time, but also within the afterglow period. Once ions are generated, they can contribute to the peak ion density of the next pulse if the off-time between the pulses is sufficiently small. When the HIPIMS cycle contains two pulses, separated by a short plasma off-time and followed by a long afterglow period, the peak ion density for the second pulse can be 5–7 percents higher than for the first pulse. With a dual cathode system and time-shifted pulsing with distinct magnetron heads it was possible to increase ion density gain up to 40% for Ti targets.     

Hysteresis behaviour of reactive high power impulse magnetron sputtering

Hysteresis behaviour during reactive High Power Impulse Magnetron Sputtering (HIPIMS) has been investigated in detail. Such analysis has been made possible by the recently developed plasma emission monitoring based reactive HIPIMS monitoring and control technology. Hysteresis curves were recorded at frequencies of 300, 450 and 600 Hz at an average power of 3.0 kW during reactive HIPIMS of Ti in Ar/O₂ atmosphere. It is shown that the target pulsing parameters, such as frequency, pulse voltage, and duty cycle do affect the overall shape of the hysteresis loop. Analysis of the hysteresis behaviour at different target pulsing parameters reveals how different regions of the hysteresis loop are affected by different pulsing parameters. The outcomes of this work demonstrate trends and explain relationships between the pulsing parameters and the hysteresis behaviour. Although the overall picture is rather complicated, it is quite clear that the hysteresis effect is induced by the same processes as in direct current magnetron sputtering, while the influence of the reactive ion implantation oxidation mechanism appears to be far more significant in reactive HIPIMS.     

Vakuummikro‐ und Vakuumnanoelektronik mit Feldemission

Vacuum microelectronics and nanoelectronics with field emission — features of breakdown voltage in vacuum gaps lower than 10 μm Further miniaturization in vacuum electronics will be possible only with field‐emitter cathodes. However in microscale vacuum gaps in the range 10 μm field emission is a dominant process in gas breakdown process, leading to signif icant deviations from the traditional Paschen's Law. At first a significant reduction of breakdown voltage is observed. The high surface‐to‐volume ratio in microscale dimensions 3 μm and in interactions with gas desorption, outgassing and gas ionization during electron field‐emission give a ignition and stabilization of micro plasmas (glow discharges) or/and micro arcs, which exist largely independent of surrounding vacuum, atmospheric or over pressure. In this range the Paschen's Law is invalid. This is an interesting approach which opens up new dimensions for basic research, field emission‐driven micro plasmas and for novel fieldemitter applications in vacuum electronics and plasma technology.     

Oxidation‐Resistant Coatings for Application on High‐Temperature Titanium Alloys in Aeroengines

High‐temperature application of titanium alloys in aeroengines is often limited by their insufficient resistance to the aggressive environment. Magnetron‐sputtered Ti–Al based coatings were developed in order to increase the maximum service temperature of conventional titanium alloys from the present 520–600 °C, the temperature limit set by the mechanical capabilities of most advanced alloys. The coatings not only demonstrated excellent oxidation resistance but also demonstrated beneficial effects on mechanical properties. Most importantly, the fatigue behavior of the substrate alloys was not degraded, a major hurdle for coating application on titanium alloys so far. Initial results on Cr‐containing Ti–Al based coatings indicated significant potential for application on titanium aluminides.     

Study of the growth of inorganic and organic electrodes onto polyethylene terephthalate substrates

Aluminum doped ZnO (AZO) 2 wt.% and un-doped ZnO thin films of different thickness were deposited by Pulsed DC Magnetron Sputtering onto Poly-Ethylene Terephthalate (PET) substrates, whereas PEDOT:PSS was spin-coated onto the AZO/PET. The optical properties of the samples were measured by in-situ Spectroscopic Ellipsometry in the Vis-fUV energy range (1.5-6.5 eV), where it was found that the ZnO energy gap decreases after a critical thickness while it remains constant for AZO thin films. Electrical characterization of ZnO films shows that the films exhibit metallic behavior independently of their thickness. Also, High Resolution Transmission Electron Microscopy revealed the growth of polycrystalline ZnO onto PET substrates. Concerning the PEDOT: PSS/AZO/PET materials, the thickness of the AZO films has been found to affects neither the fundamental energy gap nor the other absorption peaks of PEDOT: PSS.     

Magnetron sputtering – Milestones of 30 years

Since the introduction of the planar magnetron by J.S. Chapin in 1974 magnetron sputtering has become the most important technology for the deposition of thin films. Today it has conquered all industrial branches needing high-quality coatings for realization of new or improvement of existing products. The magnetron cathode combines the advantages of economic deposition even on large areas and the ability to coat very temperature sensitive plastic substrates. Main problems like poor target material utilization of the planar magnetron or process instabilities during deposition of highly insulating films have been solved by many innovations during the past 30 years. Novel films with even better quality seem to be possible with “High Power Impulse Magnetron Sputtering (HiPIMS)”. New attempts to increase sputter yield and thus film growth rate are “Sputter Yield Amplification (SYA)” or sputtering from hot targets. This paper gives a brief review on important milestones of the past three decades and outlines some ongoing developments.     

Nitridische und oxinitridische HPPMS‐Beschichtungen für den Einsatz in der Kunststoffverarbeitung (Teil 1)

Nitride and oxy‐nitride HPPMS coatings for the application in the plastics processing (Part 1) In plastics processing adhesive and abrasive wear are some of the main damage mechanisms. For the wear protection and in order to increase the tool life time as well as to improve the quality of the plastic products, binary or ternary chrome‐based coatings like CrN and (Cr,Al)N deposited by physical vapor deposition (PVD) are used. As the chemical composition of the coating has a significant impact on the surface oxide layer formed after deposition and therefore on the wetting behavior of the plastic melt on the tool surface, the aim on this work was to synthesize different coatings from the system Cr‐Al‐O‐N. Therefore, a nitride coating (Cr,Al)N and two quaternary oxy‐nitride coatings (Cr,Al)ON were deposited by using a dcMS/HPPMS (direct current magnetron sputtering/high power pulse magnetron sputtering) hybrid process by varying the oxygen flux. This articles emphasis is on explaining the influence of varying the oxygen flux during the coating process on the coating properties as well as the composite properties towards the plastic mould steel. On this basis a follow up article in the next issue will concentrated on the more application oriented system properties of the three coating systems towards a polycarbonate melt.     

Abscheidung optisch,elektrisch und akustisch wirksamer Schichten mit dem Doppel‐Ring‐Magnetron

Numerous applications in optics, electronics and sensor technology require thin dielectric films. Conventionally they are deposited by evaporation, activated evaporation, rf‐sputtering or CVD‐techniques. This paper describes the deposition of such films using reactive Pulse Magnetron Sputtering. This technology not only enables a tenfold deposition rate compared to the conventional techniques but also offers new possibilities for influencing film growth. For example it is possible to alter film composition during deposition and hence to deposit complete optical systems without interruption of the plasma process. Furthermore the energetic bombardment of the growing film can be controlled in a wide range by the pulse mode and the pulse parameters. This can be used to either deposit very dense films by strong energetic bombardment or to deposit films at low thermal load onto temperature sensitive substrates. Examples of film deposition for laser optics, electrical insulation applications and surface acoustic wave devices show how these new technological possibilities advantageously can be used for creating innovative layer systems. Film deposition is carried out in stationary mode using a Double Ring Magnetron. This type of magnetron ensures film thickness uniformity better than ± 1 % on 8” substrates by the superposition of the thickness distributions of two concentric discharges.     

Safety Analysis and Protection Measures of the Control System of the Pulsed High Magnetic Field Facility in WHMFC

A Pulsed High Magnetic Field Facility (PHMFF) has been established in Wuhan National High Magnetic Field Center (WHMFC) and various protection measures are applied in its control system. In order to improve the reliability and robustness of the control system, the safety analysis of the PHMFF is carried out based on Fault Tree Analysis (FTA) technique. The function and realization of 5 protection systems, which include sequence experiment operation system, safety assistant system, emergency stop system, fault detecting and processing system and accident isolating protection system, are given. The tests and operation indicate that these measures improve the safety of the facility and ensure the safety of people.     

Magnetron sputtering - Milestones of 30 years

Since the introduction of the planar magnetron by J.S. Chapin in 1974 magnetron sputtering has become the most important technology for the deposition of thin films. Today it has conquered all industrial branches needing high-quality coatings for realization of new or improvement of existing products. The magnetron cathode combines the advantages of economic deposition even on large areas and the ability to coat very temperature sensitive plastic substrates. Main problems like poor target material utilization of the planar magnetron or process instabilities during deposition of highly insulating films have been solved by many innovations during the past 30 years. Novel films with even better quality seem to be possible with “High Power Impulse Magnetron Sputtering (HiPIMS)”. New attempts to increase sputter yield and thus film growth rate are “Sputter Yield Amplification (SYA)” or sputtering from hot targets. This paper gives a brief review on important milestones of the past three decades and outlines some ongoing developments.     

Development of density-inclination plasmas for analysis of plasma nano-processes via combinatorial method

We have developed a plasma-process analyzer based on the “combinatorial method”, in which process examinations with a continuous variation of sample-preparation conditions can be carried out in one execution of experiment via placing substrates on a substrate holder with an inclined distribution of process parameters (ion flux and radical flux) and the distributions of particle fluxes are finely controlled and characterized via particle diagnostics. In the present study, plasma-fluid simulations have been performed to show the feasibility of the combinatorial plasma-process analyzer, in which density inclinations of the plasma parameters (ion density, radical density) are obtained via sustaining plasmas by localized deposition of discharge power using low-inductance antenna modules. The simulation results showed that density-inclination plasmas were feasible by localized power deposition for sustaining plasmas, indicating that a variety of process conditions can be efficiently analyzed via placing substrates on a substrate holder, along which process parameters are inclined.     

Abscheidung von SiOxNy Sperrschichten durch Dual Magnetron Sputtering

Silicon Oxynitride Barrier Layers Deposited by Pulsed‐DC Dual Magnetron Sputtering SiO_xN_y barrier layers have been deposited using pulsed direct current (DC) and medium frequency (MF) sputtering on large area (GEN 5) glass substrates. Several process parameters, such as discharge voltage, boost voltage, and discharge frequency were varied with the goal of increasing system productivity and reducing the arc rate during SiO_xN_y deposition. The arc rate during operation with pulsed DC dual magnetron sputtering was lower than for MF sputtering; however for the same nominal discharge power, the deposition rate using pulsed DC power supplies was slightly lower than for operation with MF. The suitability for use as a barrier layer was deduced by capping the SiO_xN_y layers with DC sputtered ZnO:Al coatings and subjecting the sample stacks to anodic and cathodic degradation and subsequent storage in a damp atmosphere.