ICMCTF2009 Session H2-2: High Power Impulse Magnetron Sputtering

Thursday, April 30, 2009 1:30 PM in Room Sunset

Thursday Afternoon

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1:30 PM		H2-2-1 Modulated Pulse Power Sputtered Chromium and Chromium Nitride Coatings J. Lin, J.J. Moore (Colorado School of Mines); W.D. Sproul (Reactive Sputtering, Inc.); B. Mishra (Colorado School of Mines); Z.L. Wu (Colorado School of Mines, and Dalian University of Technology, China); M. Hasheminiasari, S. Myers (Colorado School of Mines); R. Chistyakov (Zond, Inc.); B. Abraham (Zpulser, LLC) Modulated pulse power (MPP) sputtering is a variation of high power pulse magnetron sputtering that overcomes the rate loss issue and achieves the enhanced plasma ionization through modulation of the pulse shape, intensity, and duration. In the current study, Cr and CrN coatings were synthesized using MPP in a closed field unbalanced magnetron sputtering system under various pulse durations and the pulse modulations, which in turn strongly affect the target power density, voltage, current, and ion current density. It was found that MPP sputtering exhibits higher deposition rates than in the dc conditions when the average target power is above 10-12 W/cm² for the Cr coating depositions. Plasma diagnostics proved that extremely high level of metal ion flux with low ion energies (less than 10 eV) was identified in the MPP plasma compared to the relatively low metal ion flux in the dc and pulsed dc discharged plasma. The structure and properties of Cr and CrN coatings were characterized using x-ray diffraction, scanning electron microscopy, transmission electron microscopy, nanoindentation tests, and ball-on-disc wear test, and further compared with those synthesized using dc and pulsed dc magnetron sputtering. A high hardness of 28 Gpa has been achieved in CrN coatings deposited in MPP conditions with a floating substrate bias. The MPP CrN coatings also exhibit dense near equi-axial structure and improved tribological properties and oxidation resistance as compared to the dc CrN coatings.
1:50 PM		H2-2-3 Physical Properties and Potential Applications of High Power Impulse Magnetron Sputtering Plus (HIPIMS+) Deposited Chromium Nitride and Titanium Nitride Coatings F. Papa, C. Strondl, I. Kolev, T. Krug, R. Tietema (Hauzer Techno Coating BV, Netherlands) Chromium Nitride (CrN) and Titanium Nitride (TiN) coatings are two well studied coatings which have played a significant role in the industrialization of PVD coatings. These coatings are typically deposited via magnetron sputtering or cathodic arc. However, with the current industrialization of High Power Impulse Magnetron Sputtering (HIPIMS) technology, a new process window for such coatings is now open due to the partial ionization of the sputtered material. Due to this ionization, the coating structure and properties can be uniquely tailored. The results of coating analysis will be presented. These will include physical and mechanical properties such as crystal texture, stress and film structure. Potential industrial applications for such coatings will also be discussed.
2:10 PM		H2-2-4 Low Friction CrN/TiN Multilayer Coatings Prepared by a Hybrid HIPIMS/UBMS Process J. Paulitsch (Materials Center Leoben Forschung GmbH, Austria); P.H. Mayrhofer (University of Leoben, Austria); M. Schenkel (SVS Vacuum Coatings Technologies, Germany) CrN and TiN coatings are known for their high hardness and good wear resistance. Many research activities concentrate on the correlation between plasma conditions, microstructure and resulting properties of these coatings. Generally, the density and the mechanical properties of coatings can be improved by increasing the energy and the density of ions in the plasma. As high power impulse magnetron sputtering (HIPIMS) is known to allow high ion densities in the plasma we study the structure and mechanical properties of CrN/TiN multilayer coatings deposited by a combination of HIPIMS with conventional unbalanced magnetron sputtering (UBMS). Here we show primary results on structure, mechanical and tribological properties of CrN/TiN multilayer coatings deposited by the combined HIPIMS/UBMS deposition technique. Hardness values, obtained by an ultra micro indentation system nanoindenter, are approximately 25 GPa. The friction coefficient during dry sliding ball on disk tribo meter tests is approximately 0.2 at RT, and the wear coefficient is 6•10-16 m³/Nm, as evaluated from the wear track by optical profilometry. Structural analyses and details on the interface regions of the grown coatings are conducted by transmissions electron microscopy, scanning electron microscopy and X-ray diffraction. Our results clearly demonstrate that low-friction and wear-resistant CrN/TiN multilayer films can be prepared by a hybrid sputtering process combining HIPIMS and UBMS.
2:30 PM		H2-2-5 Industrial-Scale Deposition of Highly Adherent CN_x Films on Steel Substrates E. Broitman (Carnegie Mellon University); Zs Czigány (Research Institute for Technical Physics and Materials Science, Hungary); R. Cremer (CemeCon AG, Germany); X. Zhou (SKF Engineering and Research Center, Netherlands); L. Hultman (Linköping University, Sweden) Due to their superior wear resistance, high hardness, and low friction coefficient, carbon nitride (CN_x) coatings have been proposed as the best candidates to replace diamond-like carbon (DLC) films. The first successful industrial application of this material has been the use of very thin (~2 nm) films for the protection of hard disks since the first applications were obviously for thicker topcoats. However, the scalability of CN_x coatings produced in laboratories to industrial scale has been difficult in applications where thicker films (1-5 µm) on steel substrates were required. The main reason is the development of high compressive intrinsic stresses during deposition which causes mechanical damage, i.e., adhesion failures and delamination of films from the substrate surface. The common practice to increase the adhesion of carbon-based coatings on steel substrates is to make a pretreatment of the substrates and the use a glue layer interposed betwe en the surface substrate and the film. Recently, it has been reported that high power impulse magnetron sputtering (HIPIMS) technology produces coatings with adhesion exceeding that of arc methods. However, there are still some technical problems to solve: during the discharge, the high discharge current produces instabilities in the DC bias power supply. In this paper we study the deposition of highly adherent CN_x films using a novel HIPIMS pretreatment where two HIPIMS power supplies are used: one to establish the discharge and one to produce a pulsed substrate bias. All processing was done in a commercial CEMCON CC800 system. During the pretreatment, SKF3 steel substrates were pulse-biased in the environment of a HIPIMS of Cr plasma in order to sputter clean the surface and to implant Cr metal ions. Subsequently, carbon nitride films were prepared by DC unbalanced magnetron sputtering from a high purity graphite target in a N₂/Ar discharge at 3 mTorr. A series of depositions were obtained with samples at different bias voltages (DC and pulsed). X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), scanning transmission microscopy (STEM) and high resolution transmission electron microscopy (HRTEM) has been use to study the microstructure and the nature of the interface steel/Cr/CN_x. Identification of coating layer failures was done by the Daimler-Benz Rockwell-C adhesion test, scratch test, and Calotest.
2:50 PM		H2-2-6 Development of Ready to use Cr₂AlC Max-Phase on Complex Geometries O. Schroeter, A. Flores Renteria (Brandenburg University of Technology at Cottbus, Germany); C. Leyens (TU-Cottbus, Germany) Due to its thermo-mechanical properties, Cr₂AlC is one of the interesting MAX-phases. It is known that these materials display good mechanical properties due to their nano-laminated structure, combining the characteristics of metals and ceramics. This is interesting with regard to damage tolerant protective coatings working in an oxidative environment. This work is focused on the deposition of Cr₂AlC-coatings in an industrial PVD-coater. One of the critical steps on the application of new technologies is the up-scaling process. The use of an industrial-scale coater allows an ideal optimization of the coatings manufacture, facilitating the transfer of technology from research to industry. The obtained results demonstrate that the crystallization process of the manufactured coatings was enhanced by a post heat-treatment within the coater, applied directly at the end of the coating process. Furthermore, the distribution of the coating´s thickness and ch emical composition on complex geometries was improved by the use of high power impulse magnetron sputtering (HIPIMS) compared to direct current – magnetron sputtering (DC-MS). The enhancement of the coating´s homogeneity was achieved by using the Al-target in an HIPIMS-modus.
3:10 PM		H2-2-7 Impact Behavior of (Ti,Al,Si)N Deposited by HPPMS K. Bobzin, N. Bagcivan, S. Bolz (RWTH Aachen University, Germany) 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. This enables an active manipulation of the deposition flux eliminating line of sight behavior of sputter processes. So far the understanding of the processes within the plasma has grown steadily. Moreover some researchers have deposited different films using HPPMS or HiPIMS. 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. Coatings for that kind of applications in harsh conditions like in cutting have to provide outstanding properties. Depending on the cutting process, besides hardness and adhesion also excellent impact behavior is expected. Until now there have been reported no results about the impact behavior of HPPMS or HiPIMS cotings. 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 compared with a DC magnetron sputtered one of the same composition and coating thickness. During impact tests number of impacts, loads and inclination angle of the samples with regard to the load direction are varied. The results are related to scratch tests, morphological and topological analysis using optical and secondary electron microscopy. ¹P. Eh. Hovsepian, A.P. Ehiasarian, A. Deeming, C. Schimpf, Vacuum 82 (2008) 1312-1317 ²K. Bobzin, N. Bagcivan, P. Immich, S. Bolz, T. Leyendecker, R. Cremer, presented at PSE conference 2008, Garmisch-Patenkirchen, Germany.
3:30 PM		H2-2-8 Modulated Pulse Power Deposition of Optical Coatings R. Chistyakov (Zond, Inc.); B. Abraham (Zpulser, LLC); W.D. Sproul (Reactive Sputtering, Inc.); J.J. Moore, J. Lin (Colorado School of Mines) Modulated pulse power (MPP) sputtering is a variation of high power pulse magnetron sputtering that overcomes the rate loss issue through modulation of the pulse shape, intensity, and duration. Usually MPP uses a two-step voltage pulse to create highly ionized magnetron plasma. The first voltage step creates a low power magnetron discharge, and once it is stable the cathode voltage is modulated with an increase of this voltage, resulting in the generation of high power magnetron discharge and strongly ionized plasma. Total pulse time is typically 1-3 milliseconds. The pulse shape and duration and plasma perturbations directly affect the degree of ionization of the sputtered material. In this study, silicon, silver and reactive Al-doped zinc oxide and ITO films were deposited with the modulated pulse power sputtering approach. The applied voltage pulse shape to the magnetron generated a high power pulse discharge and directly affected the degree of ionization of the sput tered material. Nanometer scale layers of silicon, silver and reactive Al-doped zinc oxide and ITO films were alternately deposited, the thickness and structure of each nanolayer was controlled by varying the output voltage pulse shape of the MPP plasma generator. The OES of plasmas, film structure, orientation, and surface roughness were analyzed and measured. The results of the film property measurements and OES will be presented.
3:50 PM		H2-2-9 Arbitrary Voltage Pulse Shape Plasma Generator with RF Capabilities for Material Processing R. Chistyakov, B. Abraham (Zond Inc.) A new arbitrary voltage pulse shape plasma generator with capabilities to generate RF discharge was developed for RF superimposed high power pulse magnetron sputtering. Plasma generator consists from two units; arbitrary voltage pulse shape unit and RF unit. A special designed RF filter prevents RF power to penetrate inside the arbitrary voltage pulse shape unit. An arbitrary voltage pulse shape plasma generator with RF discharge capabilities gives unique opportunity for controlling plasma parameters. The principals of operation of new arbitrary voltage pulse shape plasma generator with RF generation capabilities will be presented. Method of generating multi step voltage pulses in the presence of RF discharge will be discussed.
4:10 PM		H2-2-10 An Investigation of Magnetron Magnetic Field Strength Requirements for HIPIMS P.J. Kelly, P. Barker (Manchester Metropolitan University, United Kingdom); D. Ochs (Hüttinger Elektronik GmbH, Germany); A.G. Spencer (Alacritas Consultancy Ltd., United Kingdom); G. Hintz (Hüttinger Elektronik GmbH, Germany) High Power Impulse Magnetron Sputtering (HIPIMS) is an exciting technique to produce a highly ionized sputter flux for film densification, surface modification, trench filling, adhesion promotion and other applications. Layers produced with HIPIMS show superior properties in many applications. The most investigated and promising HIPIMS application is for hard coatings in wear and corrosion protection. HIPIMS significantly changes the hysteresis curve in reactive sputtering, offering much higher deposition rates of compound thin films. Also the HIPIMS process has a significantly lower substrate heat load than standard magnetron sputtering enabling high rate coating even on temperature sensitive substrates. HIPIMS power supplies can be added to existing sputter systems with little or no system modification, making them attractive as a way of extending process capability. However the magnetron magnetic field strength must be significantly higher for HIPIMS than for standard DC sputtering. If the magnetic field is too low then the required voltage in the HIPIMS pulse rises and the desired pulse currents cannot be reached. The impact of magnetic field strength/degree of unbalance on the voltage/Current dependence has been investigated and is reported here.