Papers

ICMCTF2009 Session BP: Symposium B Poster Session

Thursday, April 30, 2009 5:00 PM in Room Town & Country

Thursday Afternoon

Time Period ThP Sessions | Topic B Sessions | Time Periods | Topics | ICMCTF2009 Schedule

BP-1 Deposition of Superhard Nanolayered CrAlBN Thin Films by Cathodic arc Plasma Deposition S.K. Kim, V.V. Le (University of Ulsan, Korea); J.W. Lee (KAIST, Korea) Thin films of CrAlBN were deposited on SKD11 tool steel substrate using Cr and AlB cathodes by a cathodic arc plasma deposition system. The influence of nitrogen pressure, AlB cathode arc current and bias voltage on the mechanical and structural properties of the films were investigated. The hardness of the film decreased with the increase of the nitrogen pressure from 1.3 Pa to 9.3 Pa. The hardness of the films increased slightly as the AlB cathode arc current was raised from 35 A to 45 A. A further increase in the AlB cathode arc current beyond 50 A decreased the film hardness. The film hardness increased from -50 V to -200 V. The film exhibited a maximum hardness of 48 GPa at the bias voltage of -200 V.
BP-2 A Cylindrical Form of the Hot Refractory Anode Vacuum Arc (HRAVA) S. Muhl (IIM-UNAM); I. Camps, O. Peña (Universidad Nacional Autonoma de Mexico); E. Camps, L. Escobar-Alarcon (Instituto Nacional de Investigaciones Nucleares, Mexico); S.E. Rodil (Universidad Nacional Autonoma de Mexico) We have designed, built and studied a cylindrical version of the Hot Refractory Anode Vacuum Arc (HRAVA) developed by the group of R.L. Boxman of Tel Aviv University, Israel. In the Tel Aviv version the anode and water-cooled cathode are in the form of two parallel plates separated by a few centimetres. After a few minutes of operation the arc and resultant plasma from the hot refractory anode extends radially outwards in all directions from the cathode-anode axis. In our cylindrical system a water cooled cylindrical aluminium cathode surrounds a central anode rod made of high density graphite mounted on a ceramic base which closes one end of the cylinder. A solenoid surrounds the outside of the cathode cable which produces a variable magnetic field along the axis of cylindrical cathode. In this way when a cathode arc is generate using a trigger pulse the magnetic field moves the cathode spot in a circular path around the inside of the cathode. The close proximity of the anode, ~2 cm, ensures that it rapidly is heated to a sufficiently high temperature that the aluminium deposited by the cathode arc is thermally evaporated and an anodic plasma, produced by the thermal emission of electrons, extends out of the open end of the cylindrical setup. The deposition rate depends on the arc current and the magnetic field. The advantage of the present arrangement is that the beam of evaporated material is directed along the axis of the cylindrical cathode. The macroparticle production is dependent on the magnetic field and the design of the ceramic cap to trap the macroparticles has been optimised. In this study we report the variation of the anode temperature, ion current, deposition rate and macroparticle density as a function of the experimental parameters.
BP-3 TiN/Ti Thin Film on Flexible PET Substrate Deposited by RF Magnetron Sputtering J.H. Huang, J.L. Lin, G.P. Yu (National Tsing Hua University at Hsinchu, Taiwan) The objective of this study was to prepare TiN/Ti thin films on PET substrate, with excellent adhesion, high gas anti-permeability and low sheet resistance. TiN/Ti thin films have been deposited on PET substrate by RF magnetron sputtering. The respective deposition durations of Ti and TiN thin films were chosen as the controlling variable in the deposition process. The gas anti-permeability, sheet resistance, surface adhesion and optical properties of TiN/Ti thin films were systematically investigated. In addition, the effects of Ti interlayer, packing factor and film thickness on these properties were also studied. The crystal structure, chemical composition and packing factor of the TiN/Ti thin films were characterized by glancing incidence X-ray diffraction (GIXRD) and Rutherford backscattering spectrometry (RBS), respectively. Water vapor transmission rates (WVTR) of the TiN/Ti thin films were measured using a MOCON instrument. The electrical resistance was determined using a four-point probe. Experimental results showed that the structure of TiN thin films deposited on both PET and Ti/PET substrates were amorphous. The film adhesion for all TiN/PET and TiN/Ti/PET samples was excellent. The Ti interlayer could effectively increase the packing factor of TiN thin films. The gas permeability of TiN/Ti thin films was related to the synthetic parameter of packing factor × total thickness of the coating. The WVTR of the specimens would level off, if the TiN/Ti thin films reached a critical thickness of about 100 nm in this study. The sheet resistance of the TiN/Ti thin films decreased with increasing film thickness. The packing factor of the TiN thin film increased with the thickness of Ti interlayer and hence decreasing the sheet resistance. The results indicated that adding a Ti interlayer could effectively improve the gas permeability and sheet resistance of the TiN/Ti thin films on PET substrate. The superior performance of the thin films nearly reached the requirements for the applications in flexible LCDs, inorganic solar cell, and thin film battery.
BP-4 Preparation, Structure and Characteristic Study of TiVCrAlN Thin Film D.-C. Tsai, M.-J. Deng, F.-S. Shieu (National Chung Hsing University, Taiwan) Al-doped TiVCrN thin films were prepared by dc magnetron cosputtering, in which were utilized for TiVCr and Al targets, respectively. Glancing incidence X-ray diffraction revealed a simple face-centered cubic solid solution phase with a (200) preferred orientation for the Al-doped films, in contrast to the undoped ones possessed (111) and (200) preferred orientation predominantly, indicating that Al addition can lead to important enhancement of the adatom mobility and consequently trend to thermodynamic favorable orientation. The attendance of Al input power also play an important role on orientation and grain size. These, in turn, also cause lattice shrinks and grain growth. However, it is observed by transmission electron microscopy that the microstructure morphology seem to be independent form the Al concentration, implying that barrier existing at the boundary is not enough to be overcome. The variation trend of the surface roughness which well conforms with that of the grain size is observed. With increasing Al concentration, the hardness and resistivity increase. In consideration of the variation trend of mechanical and electrical property of the films, the factor is attributed to a competition of grain growth and bonding characteristic.
BP-5 Interlayer Effect on the Detaching Mechanism for Mo-Ru Hard Coatings Y.-I. Chen (National Taiwan Ocean University, Taiwan); L.-C. Chang (Mingchi University of Technology, Taiwan); B.-N. Tsai (National Taiwan Ocean University) Hard coatings have been used as a protective coating on the top surface of the glass molding die. Damages such as scratch, peeling, atomization and adherent glass scars were the main injuries occurred on the surface of the protective coating, which degraded the surface quality and limited the lifetime of the molding die assembly. In a realistic mass production process, recycling of the damaged coating was necessary for the cost and time issues. Thus, detaching the damaged coating is an important process and chemical stripping was proposed ever. Etching pits in the protective coating and selectively oxidized interlayer provided feasible paths for the stripping. In this study, Mo-Ru coating was used as the protective hard coating, while Ni, Cr, Ti and Ta were used as the interlayers to evaluate the detaching mechanism by using the etchant, ammonium cerium (IV) nitrate – acetic acid solution. The chemicals solved in the etching solution were investigated by an inductivel y coupled plasma optical emission spectroscopy. It is verified that Ni and Cr with lower ionized valances were easily reacted with the etchant. On the other hand, Ti and Ta interalyers were resistant to the etchant and suitable to protect the substrate.
BP-6 Growth of α-(Al,Cr)₂O₃ Thin Films by Reactive r.f. Magnetron Sputtering D. Diechle, M. Stueber, H. Leiste, S. Ulrich (Forschungszentrum Karlsruhe, Germany); V. Schier (Walter AG, Germany) Advanced thin film materials for cutting tool applications require complex property profiles including high hardness, toughness, wear and corrosion resistance. Such materials are expected for example in the Al-Cr-O system. The materials science approach behind this work is to quench Al-Cr-O thin film materials in a metastable corundum-type solid solution structure directly from the vapor phase at deposition temperatures significantly below the temperature range of the thermodynamic stable phase which exists only above 1300°C in the corresponding Al-Cr-O phase diagram. First, we will describe a combinatorial approach using a segmented target consisting of aluminum and chromium plates for the deposition of Al-Cr-O thin films by reactive r.f. magnetron sputtering. This experimental procedure results in the growth of coatings of different composition and microstructure in dependence of the sample positions in relation to the target. For specific deposition conditions stoichiometric, nanocrystalline solid solution strengthened (Al_1-x,Cr_x)₂O₃ thin films were grown in a corundum-type structure. Secondly, we derive from these experiments fixed individual material compositions and use homogeneous metallic targets with an appropriate Al:Cr composition for reactive r.f. magnetron sputtering. Similar coatings grown by these different approaches will be compared with respect to their constitution, microstructure and properties. The deposition experiments are carried out with a Leybold Z 550 PVD machine in an argon–oxygen plasma. The cathode power is set to 500 W in r.f. mode, and the total gas pressure is 0.65 Pa in all experiments. During deposition the substrate temperature is controlled in the range from 180°C to 600°C. In addition, a substrate bias up to -400 V is induced with a second r.f. power supply. Commercial cemented carbide substrates and silicon wafers are coated. The coatings are characterized by determining their thickness, Vickers micro hardness, residual stress, density, chemical composition, constitution (by XRD) and their microstructure (by REM and TEM).
BP-7 Optoelectronic and Structural Properties of ZnO:Ga Thin Films Prepared by Pulsed DC Magnetron Sputtering W.-T. Yen, Y.-C. Lin (National Changhua University of Education, Taiwan) The ZnO:Ga (GZO) thin films were prepared on a type Corning 1737 glass substrate by pulsed DC magnetron sputtering. The effect of pulse frequency and film thickness on the thin film structural and optoelectronic properties was investigated. After deposition, the deposition rate and thickness of the thin film were measured and analyzed using an a-step profiler. An X-ray diffraction (XRD, CuKα，λ=1.54052Å) analysis was performed to investigate the crystallographic structure of the ZnO:Ga film. The surface morphologies of the films were observed with an atomic force microscope. Field Emission Scanning Electron Microscopywas performed to observe the microstructures of the ZnO:Ga films. The electrical properties were obtained by Hall effect measurements. The optical transmittance of the ZnO:Ga films were measured by UV-visible spectrometer. PL measurements were carried out by the excitation of a He-Cd laser with 325nm wavelengths at room temperature.The experimental resu lts showed that a highly c-axis (002) preferred orientation and lowest resistivity are obtained by a pulsed frequency of 10kHz condition. Following an increase in the thickness of GZO thin film, the grain size of GZO thin film and carrier mobility also increased, resulting in the resistivity of GZO thin film decreased. From the XRD spectra, the full width at half maximum spectra gradually broadened out, which predictably could be because the Ga3⁺ was being replaced by Zn2⁺, causing internal defects and generating a deformed lattice, resulting in the signal broaden. The lowest resistivity of 2.01×10-4ω-cm for the GZO thin film is obtained under the pulse frequency of 10kHz and thin film thickness of 500nm, this result is better than that from previous studies. In addition, the Rms of surface roughness is 2.9 nm, the optical transmittance in visible region is 86%, the energy gap of GZO thin film is approximately 3.83eV are obtained.
BP-8 Formation, Characterization and Properties of Al-doped Vanadium Pentoxide Nanorods by Chemical Vapor Deposition M.W. Huang (National Chung Hsing University, Taiwan); Y.C Su, L.W Chang (National Tsing Hua University, Taiwan); F.-S. Shieu (National Chung Hsing University, Taiwan); H.-C. Shih (Chinese Culture University, Taiwan) Al-doped vanadium oxide nanorods were synthesized on Si（100） and glass substrates by chemical vapor deposition using solid precursors of vanadium oxide powders（V₂O₅ 99.5％, 1.185 g）mixed with aluminum powders（Al 99.5％, 0.015 g）in an Ar atmosphere（5x10^-2 Torr, 10 sccm）at 700℃ for 1 hour. Structure, morphology, and optical property of the nanorods were characterized by SEM, HRTEM, EDS, XRD and XPS. The diameter of Al-doped V₂O₅ nanorods were about 50 to 100 nm and length of several micrometers with an orthorhombic crystal structure growing along direction [020] with sharp diffraction peaks at (010) and (020). XPS patterns showed three conspicuous binding energy peaks of (V) 2p_3/2 at 518 eV, (V) 2p_1/2 at 525 eV, (O) 1s at 530 eV and (Al) 2p at 71 eV. The V 2p_3/2 binding energy centered at 518 eV with an FWHM of 1.2 eV is characteristics of vanadium in the +5 oxidation state which is well consistent with the value of V₂O₅ structure. The electrical properties of a single Al-doped V₂O₅ nanorod was conducted in-situ and show that the current and conductivity both decrease obviously, because V₂O₅ is an n-type semiconductor and Al is a ρ-type doped element, the holes would counteract with electrons which led to the decrease of carrier mobilities. ¹C. Díaz-Guerraa and J. Piqueras, J. Appl. Phys. 102, 084307 (2007) ²Nilima V. Hullavarad,z Shiva S. Hullavarad, and Pramod C. Karulkar, J. Electrochem. Soc., 155 4 K84-K89 (2008) ³Jitae Park, In Hwan Oh, Eunmo Lee, Kyu Won Lee, and Cheol Eui Lee, Appl. Phys. Lett. 91, 153112 (2007).
BP-9 Characterization of Superlattice CrN/AlN Coating for Semiconductor Packaging Applications D.-Y. Wang, W.-H. Tzeng (Mingdao University, Taiwan) The CrN coating deposited by PVD technique has been adopted as the replacement for the conventional hard chrome plating to protect the semiconductor packaging dies for its environment-friendly process and superior tribological properties. To further extend the service life of the packaging dies against the ever-increasing abrasiveness, stickiness, and corrosiveness of the packaging resin, a CrN/AlN superlattice coating was synthesized by using the unbalanced magnetron sputtering technique. This study demonstrated the obvious dependence of the superlattice characteristics with the periodic double-layer thickness, optimized at 4 nm. The XRD analysis revealed the meta-stable cubic structure of AlN layer within the CrN/AlN superlattice matrix, which possesses a B1-NaCl crystal structure. The typical hexagonal wurtzite crystal structure of the bulk AlN was suppressed by aligning to the cubic CrN lattice along the superlattice boundaries. The microhardness of the superlattice CrN/AlN coating was measured at 28.1 GPa, significantly higher than the monolithic CrN coating. At the periodic thickness of 4 nm, the CrN/AlN superlattice coating exhibited very stable oxidation behavior with a relative weight increase of only 0.2-0.25% after exposure to a 1000-°C TGA test. Results showed that the CrN/AlN superlattice coating is capable of withstanding the abrasive high-temperature service environments up to 800°C without much degradation. Finally, the contact angle measurement revealed the improved hydrophobic property of the CrN/AlN superlattice coating, which allows easy mold- releasing during the prolonged packing operation.
BP-10 Effects of Dopant Ion and Mn Valence State in the La_1-xA_xMnO₃ (A=Sr, Ba, Ca) CMR Films for Infrared Sensor S.G. Choi, A.S. Reddy (Yonsei University, Korea); H. Ryu, B.-G. Yu (Electronics and Telecommunication Research Institute, Korea); H.-H. Park (Yonsei University, Korea) La_1-xA_xMnO₃ (A are divalent alkaline earth ions such as Ca, Sr, and Ba) colossal magnetoresistance (CMR) films have been received much attention for infrared sensor resistor because they have a high temperature coefficient of resistance (TCR) and a low noise property which are the most important figure of merit to infrared sensor, for example, microbolometer. Electron transport properties in the CMR oxides with perovskite structure are known to depend on the ionic size and oxidation state of the element at the rare-earth elemental site, which influences the bond length and bond character of Mn-O and oxidation state ratio between Mn³⁺ and Mn⁴⁺. To understand the relation between structural and electrical properties of Mn-based oxides films, we investigated CMR films by varying the dopant ions and the ratio of the oxidation state of Mn ion. In this research, the effects of various dopants such as Ca, Sr, and Ba ions and the ox idation state of Mn ion on the structural and electrical properties of CMR films were investigated. For these purposes, La_1-xA_xMnO₃ films with same tolerance factor and then no internal lattice strain difference in the film were prepared. Also CMR films which have different oxidation state of Mn³⁺ and Mn⁴⁺ were also prepared by varying the amount of divalent A ions while maintaining the tolerance factor. In this way, a correlation between dopant and the oxidation state ratio of Mn³⁺ and Mn⁴⁺ in the CMR thin films which affects crystal structure, TCR value and 1/f noise could be systematically investigated.
BP-11 Composition-Constitution-Morphology Relationship of Al₂O₃ Thin Films Deposited by Plasma Assisted Chemical Vapor Deposition J.M. Schneider, K. Jiang, K. Sarakinos, D. Music, J. Mayer (RWTH Aachen University, Germany); R. Snyders (Université de Mons, Belgium); St. Konstantinidis (University of Mons-Hainaut, Belgium); T. Markus (Forschungszentrum Jülich, Germany) We have studied the correlation between the chemical composition, constitution and morphology of Al₂O₃ using experimental and theoretical means. Plasma-assisted chemical vapor deposition, with an AlCl₃-Ar-H₂-Cl₂ precursor mixture, was used to synthesize γ- and α-alumina thin films. These coatings contain from ~1.0 to ~2.0 at.% of residual Cl depending on the constitution, where larger Cl contents are found in γ-alumina. Plasma chemistry, studied by optical emission spectroscopy, suggests that Cl is incorporated in these coatings as a result of incomplete dissociation of AlCl₃ precursor. Combining scanning electron microscopy, transmission electron microscopy (TEM), electron dispersive X-ray analysis (EDX) and ab initio calculations, we have studied the formation of the pores found in these films. Pore populations with diameter of about a few tens of nm and in the µm range can be observed in the alumina matrix. Chlorine desorption measurements show chlorine release from γ- and α-alumina films as the temperature is increased above the growth temperature and a second onset temperature at about 1000°C. Based on ab initio calculations, we have established that Cl can be incorporated in both γ- and α-alumina. The Cl content may be larger in γ-alumina, because there are more possible incorporation sites as compared to those in α-alumina. Furthermore two Cl atoms are likely to agglomerate since the total energy is reduced compared to an un-agglomerated configuration. We propose that Cl agglomeration is the first step towards Cl₂ molecule formation and subsequent precipitation of Cl to form bubbles. It can be learned that the Cl₂ incorporation has to be minimized during growth of dense alumina coatings.
BP-12 Characterization of Binary, Ternary and Quaternary Hard Coatings in the Material System V-Al-C-N Produced by Industrial Scale Reactive Magnetron Sputter Deposition Sz. Kolozsvári, P. Pesch (TZO Rheinbreitbach GmbH, Germany); C. Ziebert, M. Stueber, S. Ulrich (Forschungszentrum Karlsruhe, Germany) Binary, ternary and quaternary hard coatings in the system V-Al-C-N (VN, AlN, VC, VAlN and VAlCN) were deposited by industrial-size/industrial scale reactive d.c. and r.f.-magnetron sputtering in an Ar/N and an Ar/CH₄ plasma from a V target and/or Al target, respectively from an VAl₂₀-target (V target with 20 Al-plugs). For each experiment, Si (100) substrates and polished 1.2379 steel substrates were placed on the rotating substrate table with variable rotation speed and rotation axes. VN coatings were deposited at a constant Ar gas flow of 250mln, while the bias voltage applied to the substrate table was systematically varied between -80 and -200V. VC coatings were deposited at constant Ar:CH₄ gas flow ratio (250:60) and systematically varied bias voltage between -80 and -200V and respectively at constant bias voltage from -170V and varied Ar:CH₄ ratio through changing the CH₄ amount in the plasma. For the deposition of AlN, VAlN and VAlC N coatings the bias voltage, the Ar:N ratio and the total gas pressure were varied. The chemical composition of the obtained coatings was determined by electron microprobe analysis and the crystal structure of the films was characterized by X-ray diffraction. The influence of the process parameter variation on the mechanical properties hardness, reduced elastic modulus and critical load of failure have been studied by microindentation and scratch test. The surface roughness of the as-deposited samples was examined as a function of the initial substrate surface roughness. It was possible to achieve a large variation in the hardness in the range from 700HV_0.005 to 3100HV_0.005 and in the coefficient of friction in the range from 0.2 to 0.7. Finally, the specific conditions for the formation of large-area VN, AIN, VC, VAlN and VAlCN nanoscale coatings in industrial-size coating facilities are described in terms of process engineering.
BP-14 Influence of Bias Voltage on the Microstructure and Physical Properties of Magnetron Sputtered ZrSiN Nanocomposite Thin Films N. Cusnir, D. Oezer, C.S. Sandu, R. Sanjines, A. Karimi (EPFL, Switzerland); J. Patscheider (EMPA, Switzerland) We report an investigation concerning the influence of ion bombardment on the morphology and physical properties of Zr-Si-N nanocomposite thin films. The films were deposited by reactive magnetron co-sputtering from individual Zr and Si targets. The Si content of films was varied by changing the power applied to the Si target. The increase of ion bombardment energy was obtained by applying a negative potential U_b to the substrate. The evolution of the crystalline structure, grain size and lattice constant was mapped out using grazing incidence X-ray diffraction measurements. The optical properties were studied by spectroscopic ellipsometry, the electrical resistivity was measured by Van der Pauw method between 20K and 300K and the hardness was investigated by nanoindentation. Films deposited at a substrate temperature of T_s= 510 K with U_b = 0 V exhibit (111) preferential orientation. The maximum nanohardness of 30 GPa is reached at 4 at.% Si concentrat ion, these films exhibit a mean crystallite size of about 14 nm and a SiN_x coverage on ZrN grain boundaries of about 0.5 monolayer in thickness. In contrast, films deposited at T_s= 510 K with a bias voltage of U_b= -150 V exhibit less pronounced columnar structure with small crystallites having many crystallographic orientations. The maximum nanohardness of 38 GPa observed in these films is reached at about 1.2 at.% Si while the average grain size is 10 nm and the SiN_x surface coverage is 0.35. These results are compared with our prevue results on ZrSiN films deposited at various substrate temperatures and discussed in terms of atomic diffusion and phase segregation effects due to the ion bombardment.
BP-15 Wear Resistance of PVD Magnetron Sputtered ZrTiBN Thin Films O. Jimenez, M. Audronis, K. Kanakis, A. Leyland, A. Matthews (University of Sheffield, United Kingdom) It is well known that hard thin films containing transition-metal nitride or boride phases (e.g. ZrN, ZrB₂and TiB₂) offer outstanding properties such as high hardness, high melting point and chemical inertness. ZrN and (Zr,Ti)N coatings have already been shown to exhibit good tribological behaviour and are considered as very promising candidates for applications related to improved protection against wear (among many others). In this work thin PVD ZrTi(BN) coatings were successfully deposited onto mirror-polished ASP23 tool steel, using medium frequency (20-350 kHz) asymmetric bipolar pulsed magnetron sputtering (PMS) technology. Coatings were obtained using a rectangular target composed of three pieces (Zr/TiB₂/Zr) under different conditions of bias voltage and N₂content-the latter being used as a reactive gas at different flow rates, to promote the formation of hard Zr nitride-containing phases. The phase analysis, morphology and mechanical property evaluation of the coatings were studied by means of glancing angle X-ray diffraction (GA-XRD), cross-sectional scanning electron microscopy (SEM) images and nanoindentation, respectively. The tribological tests were carried out by using a UMT multi-specimen test system, at a low reciprocating-sliding frequency of 5Hz (with humidity and temperature continuously monitored and recorded), with the resulting tribological behaviour and wear mechanisms being analyzed by surface profilometry and by SEM evaluation of the worn surfaces. Coatings were tested at an applied normal load of 1N and over sliding distances of 1000 m and 1500 m against a 4 mm diameter polycrystalline high-purity alumina ball counterface. SEM images revealed that the coatings are fully dense, featureless and defect-free. Phase identification performed by GA-XRD revealed a partially amorphous structure, with (Zr,Ti)N and Zr metal being the main constituents. Hardness values above 20 GPa were measured fo r most of the coatings deposited at different N₂flow rates, while hardness for those containing no nitrogen was found to be significantly lower-due to the absence of hard ceramic phases. Wear resistance was found generally to be good; most of the samples survived 1000 m of sliding distance, exhibiting a moderately low friction coefficient of ~0.4
BP-16 Synergy Between High Temperature and Wear In CrSiN Nanocomposite Coatings Deposited by Hybrid Arc /Magnetron Process A. Mège-Revil, P. Steyer (INSA de LYON, France); J. Fontaine, M. Guibert (Ecole Centrale de Lyon, France); J.-F. Pierson (Ecole des Mines de Nancy, France); C. Esnouf (INSA de Lyon, France) CrN, Cr2N, CrN+Si (6 at.%) and Cr2N+Si (3 at.%) thin films were deposited on M2 steel by an hybrid process in which Cr was deposited from an arc-evaporated target while Si was magnetron sputtered. XRD and HRTEM showed that the nanocomposite structure was obtained only in the case of CrN+Si. The grains of Cr2N are shrunk by adding Si. Consequently, a large amorphisation of the intergranular regions is observed, preventing the formation of a barrier layer of silicon nitride. As a result, nanohardness measurements confirmed that adding Si in CrN improved the mechanical properties, a phenomenon which is not observed in the case of Cr2N and Cr2N+Si. Isothermal and dynamic oxidation were followed by TGA. The oxidation resistance of CrN was found to be greatly enhanced by the nanocomposite structure. Consequently, no such improvement was observed between Cr2N and Cr2N+Si. In aggressive tribo-oxidative conditions, Cr2N-based coatings were too brittle to sustain the shortest tes t. On the contrary, a coated ball of CrN withstood up to 20 meters of alternated rubbing on mirror-polished steel. Finally, the CrN+Si coated ball once again proved its multifunctionality with a Specific Wear Energy three times more important than that of CrN at room temperature and twice at 150 and 300°C.
BP-17 Mechanical and Electrochemical Properties of CrZr-Si-N Coatings Y.S. Kim, G.S. Kim, S.Y. Lee, S.C. Oh (Korea Aerospace University, Korea) For many years, chromium nitride films have been extensively used as a protective hard coating in the various mechanical industries due to their good wear resistance, high thermal stability as well as good corrosion resistance. However, in spite of their excellent properties, the CrN films show inadequate properties for some applications as high speed machining, or at high temperature or in severely corrosive conditions because of the limitations of binary system. Recently, in order to improve the mechanical and chemical properties of the CrN, the Cr-based ternary nitride coatings such as Cr-W-N, Cr-Al-N, Cr-Si-N and Cr-Zr-N have been developed and their excellent properties are reported in many papers. However, investigations on the synthesis of Cr-based quaternary nitride coatings are very limited. In this study, quaternary CrZr-Si-N films with various Si contents (@footnote 1@ at.%) were synthesized by closed field unbalanced magnetron sputtering with vertical magnet ron sources and their crystalline structure, morphology, mechanical and electrochemical properties a function of Si content were investigated. Preliminary results showed that the characteristics of the CrZr-Si-N films such as hardness, surface morphology, friction coefficient and cross-section structure were very similar irrespective of the Si content (@footnote 2@ at.%), i.e. all films have high hardness of 32~33 GPa, very smooth surface roughness of 1.1~0.7 nm (Rms value), very low average friction coefficient of 0.22~0.23 and dense microstructure. Detailed experimental results included electrochemical properties will be presented. ¹ ≥6.4 ²@ ≥6.4
BP-18 Phonon Anomalies in Multiferroic BiFeO₃ Epitaxial Thin Films Prepared by Using Pulsed Laser Deposition M.K. Singh, S. Dussan, G.L. Sharma, R. Katiyar (University of Puerto Rico) Ferroelectromagnetic materials, also known as multiferroics, exhibit ferroelectric (or antiferroelectric) properties in combination with ferromagnetic (or antiferromagnetic) properties. BiFeO₃ (BFO) is known to be only is known to be the only material that exhibits multiferroism at room temperature. BFO thin films were grown on (111) STO substrates by employing pulsed laser deposition (PLD) method. The average thickness of these films, as estimated using field-emission scanning electron microscopy, was 300±3 nm. To examine the structure of the PLD-grown BFO film on a STO (111) substrate, θ-2θ x-ray diffraction (XRD) was carried out. The pattern reveals purely [111]_C-oriented rhombohedral BFO reflections. Raman spectrum of (111) oriented BiFeO₃ (BFO) thin film was studied in temperature range between 27°C – 1000°C. Observed Raman modes at 136, 162, and 212 367, 550 cm^-1 show anomalous changes in frequencies, line w idth and integrated intensity between span of temperature range 250- 400° C i.e. around magnetic phase transition (T_N). The sign and magnitude of such anomalous behavior appears to be an experimental evidence of perturbation antiferromagnetic ordering coupled with octahedral tilting reveals strong spin-phonon coupling around T _N. The soft mode behavior of A₁ Raman modes at 136 and 162 cm^-1 was observed directly and reveals a decrease of the Curie temperature (T_C ) of the strained film, which was originally suggested by M. S. Kartavtseva and co workers [Thin Solid Films, 515 (2007) 6416].
BP-19 Characteristics of Silicon-Nitride Films Deposited by Internal Linear Inductively Coupled Plasma Source G.H. Gweon, K.N. Kim, J.H. Lim, G.Y. Yeom (SungKyunKwan University, Korea) Silicon-nitride film have been widely used in a various of important applications from semiconductor possibly to flat panel display, such as passivation layers for diverse microelectronics, a gate dielectric material for thin film transistor (TFT), and as anti-reflection (AR) coating for solar cell. Especially, due to their chemical inertness, excellent dielectric properties, and thermal stability, many researchers have been studied to develop high quality silicon-nitride films using a various type of plasma sources. In this study, to obtain high quality silicon-nitride films, internal linear inductively coupled plasma source was used. The internal linear antenna (U-type) was made of 10 mm diameter copper tubing covered by quartz tubing of 25 mm diameter and antenna was connected to the power supply while the other end was connected to the ground. In addition to, we carried out the deposition of silicon nitride thin films by using internal linear ICP source and investig ated the effect of the ratio of NH₃ to SiH₄ on the properties of thin film, such as deposition rate, optical properties, relative composition, and surface morphology. The gas mixture of SiH₄/NH₃/Ar was fed to the chamber where SiH₄ and NH₃ gases were used as the reaction gases and Ar gas as the ignition gas. Also, the compositions and binding states of the films were measured using X-ray photoelectron spectroscopy (XPS; VG Microtech Inc., ESCA2000). The binding states were also measured by a Fourier transform infrared spectrometer (FTIR; Bruker, IFS-66/S). The surface morphology of thin films was measured by a field emission scanning electron microscope (FE-SEM; Hitachi S-4700).
BP-22 Preparation and Mechanical Properties of Reactively Sputtered Complex Al_xCoCrCuFeNi Oxide Films T.K. Chen, C.S. Lin, M.S. Wong (National Dong Hwa University, Taiwan) Complex oxide films of multi-element Al_xCoCrCuFeNi (the molar ratio of x =0-2) were prepared by reactive sputtering of homogeneous alloy targets and co-sputtering of an alloy target and an Al target. . The as-deposited films are nanocomposite in nature and comprise single cubic-(c-) spinel crystalline phase. The film hardness increased with aluminum content reaching a maximum hardness of 22.6 Gpa for Al₂CoCrCuFeNi oxide film. After annealing at 500°C, the hardness enhanced to 26 Gpa. These hardness values are among the hardest available hard oxide materials. Post-annealing at higher temperature dramatically decrease film hardness mainly due to the precipitation of softer second phase and the cracks induced by the precipitates. Further enhancement in film hardness are attempted by adding more Al into the film and by applying substrate bias during film deposition.
BP-23 Nucleation and Growth of Diamond by Pulsed Liquid Injection CVD Using Tequila as Precursor L.M. Apatiga (Campus Juriquilla, Mexico); J. Morales (Universidad Autonoma de Nuevo Leon, Mexico) Tequila, identified as silver tequila 100 % agave (pure tequila), was used as carbon source in the synthesis of diamond. By using a Pulsed Liquid Injection Chemical Vapor Deposition reactor, diamonds of 200-400 nm in diameter were deposited at 850°C on silicon substrates. According to Fourier Transform Infrared Spectroscopy studies tequila is formed basically by ethanol and water, as well as certain chemicals, among them higher alcohols, fatty acids, esters, etc. produced by the fermentation and distillation processes, during its elaboration. Tequila has the right concentration of carbon, hydrogen and oxygen atoms to form CVD diamond, its composition falls into the diamond growth zone, inside the triangle of the ternary C-H-O gas phase diagram. The deposited diamonds were characterized by Scanning Electron Microscopy and Raman spectroscopy.
BP-24 Ion Energy Distribution and Langmuir Probe Studies in an Ar/O₂ Discharge During Al₂O₃ Deposition S.L. Mensah (University of Arkansas); H.H. Abu-Safe (Lebanese American University, Lebanon); M.H. Gordon (University of Arkansas) Local plasma parameters and ion energy distributions for plasmas used to deposit low-temperature alpha-Alumina without a chrome template layer were investigated as a function of power, pressure, and oxygen partial pressure in the vicinity of the substrate using a Langmuir probe and energy-resolved mass spectroscopy. The thin films were deposited by a mid-frequency AC reactive magnetron sputtering system. In this work, power ranged from 4 to 8 kW, at pressures 2, 5 and 8mTorr with oxygen partial pressure ranging from 20-80%. Monitored species include Ar⁺, O⁺, O₂⁺, and Al⁺. The EQP results show that, at constant total pressure, changes in the ratio of the partial pressures of Ar/O₂have a negligible effect on the energy distributions of the species, but we noticed an effect on the energy distribution of the species when the total pressure is changed. Similarly, changes in pressure influence the characteristics of the alumina films de posited. Analytical characterization of the thin film shows a correlation between the changes in pressure and phase and morphology of the films. Alpha-alumina phase is predominant when low total pressures are coupled with high oxygen partial pressure and high power. Here we correlate the plasma properties to the differences noted in the deposited thin films to explain why alpha alumina films are obtained.
BP-25 Characterization and Mechanical Properties of Magnetron Sputtered Iron Nitride Coatings H.-R. Stock, I. Eisbrecher, H. Teuber (Stiftung Institut fuer Werkstofftechnik, Germany) Iron nitrides produced by thermochemical procedures like gas or plasma nitriding have interesting properties. For example iron nitride surfaces are machinable with single crystal diamond tools, whereas cutting of pure α-iron surfaces cause severe wear of the diamond tool. We used a d.c. magnetron sputtering unit (CemeCon, CC800/9) with an austenitic manganese steel target (X120Mn12, AISI A128 grade A). Argon and nitrogen as reactive gas were added by mass flow controllers. As substrates polished steel samples were used. With a target power of 3000 W layers of 7 µm thickness could be deposited within two hours. X-ray diffraction reveals the existence of the γ’-phase Fe₄N. To achieve good adhesion a titanium interlayer was deposited prior to the iron nitride layer by means of a titanium target. The coatings were optimized in respect to hardness and adhesion and characterized regarding to chemical composition, morphology, microhardness and topogra phy by electron microscopy, ultra microhardness testing, atomic force microscopy and glow discharge optical emission spectrometry, respectively.
BP-26 Multilayer Chromium Based Coatings Grown by Direct Liquid Injection CVD F. Maury (ENSIACET, France); A. Douard, S. Delclos, D. Samelor, C Tendero (CIRIMAT, France) There is a great interest for multilayer hard coatings because they exhibit enhanced properties resulting from their nanostructuration. Such coatings are generally constituted of carbide and nitride and they are deposited under very low pressure by plasma and PVD processes. These vacuum techniques permit the growth of heterostructures with nanometric thick individual layers and sharp interfaces, which are two requirements for advanced performances. However, both to develop more economical processes and with the goal of continuous deposition applications, the CVD processes operating under atmospheric pressure or near atmospheric pressure are particularly attractive. In this paper we show that the combination of pulsed direct liquid injection and the use of metalorganic precursor (DLI-MOCVD) is a promising route for the growth of nanostructured multilayer coatings. Chromium metal as well as chromium carbide and nitrides single coatings have been deposited at 500°C by thes e processes using liquid solution of bis(benzene)chromium as Cr molecular precursor. Then, CrC_x/CrN and Cr/CrN nanostructured multilayer coatings with a bilayer period as low as 25 nm have been grown. Structural characterizations and preliminary mechanical properties of these metallurgical coatings are presented and discussed.
BP-27 Characteristics and Homogeneity of Direct and Pulse Current Electrodeposited High Phosphorus Content Ni-P Coatings C.C. Wu, H.S. Huang, K.J. Chang, F.B. Wu (National United University, Taiwan) High phosphorus content Ni-P binary alloy coatings were prepared by direct current (DC) and pulse current (PC) electroplating techniques using Brenner type solution. The characteristics and homogeneity, including microstructure, phase, composition, deposition rate, and thickness uniformity, with respect to plating parameters for both coatings were evaluated for comparison. A high averaged P content of 24at.% could be achieved in both DC and PC Ni-P coatings deposited under current densities ranged from 50 to 125 mA/cm². Using a high current density of 100 mA/cm² for DC plating, the deposition rate was raised significantly, yet the elemental distribution of P decreased drastically down to 12at.% in the vicinity of substrate edge. Through the modification of the substrate edge geometry and decrease of current density, a high P content Ni-P coating with excellent coverage could be retained. On the contrary, the coating deposited by PC plating showed a super ior thickness uniformity and deposition rate. The laminar structure and severe pinhole distribution in the Ni-P coating edge due to hydrogen reduction of DC plating could be improved by the pulsating modulation. In addition, the plating mechanisms for cathodic reactions of both DC and PC plating techniques were intensively discussed.
BP-28 Effect of Pulse Plating with Ultrasonic Agitation on the Corrosion and Wear Properties of Eco-friendly Trivalent Chromium Layers Prepared in Chromium Sulfate Bath S.C. Kwon (Korea Institute of Materials Science, Korea); J.J. Lee, Y. Choi (Sunmoon University, Korea) Eco-friendly trivalent chromium layers was prepared in a modified chromium sulfate bath by pulse plating with ultrasonic agitation to replace hexavalent hard chromium coating in industrial fields. Deposition rate of the trivalent chromium layers by ultrasonic pulse plating was about 0.021mm per hour, which was faster in a direct current (D.C) plating than pulse and ultrasonic pulse plating at a same total on-time. Micro-hardness of the ultrasonic pulse plating are about 856 Hv , which is lower than those of pulse plating (864 Hv) and direct current plating (915 Hv). Wear resistance of the trivalent chromium layer prepared by ultrasonic pulse plating is higher than that of the chromium layer prepared by a direct current plating. The Ultrasonic agitation during pulse plating resulted in increasing neutral salt fog spray life and wear resistance, that is related to smaller crack size and more broad size distribution of the trivalent chromium layers.
BP-29 BGA Cutter Improvement Utilizing Nano-TiAlN Coating Layers Synthesized by Cathodic Arc Ion Plating Process S.H. Huang (National Chiao Tung University, Taiwan); T.-E. Hsieh (National Chiao Tung Univesity, Taiwan); C.-W. Chen (Gigastorage Corporation, Taiwan) Various Ti/Al concentration ratio targets were used in a filtered cathodic arc ion plating system (FCAIP) to deposit the multiple TiAlN layers on silicon wafer substrate and WC cement BGA cutters at various modulation wavelengths(λ). Transmission Electron Microscopy (TEM), grazing incidence x-ray diffraction (GIXRD), engery dispersive x-ray spectrometer (EDS), nanoindentation and CNC BGA router were used to evaluate the characteristics of TiAlN layers and performance of BGA cutters. TEM analysis revealed the modulation wavelengths of nanolayers were less than 10 nm at various rotation speed in FCAIP chamber. TEM and GIXRD analyses showed the crystal structure of TiAlN layer with the maximum hardness was NaCl(B1) structure using the target with the composition Ti_0.5Al0.5. The maximum hardness of multiple TiAlN layer measured by nanoindentation was 43 Gpa, while the TiAlN monolayer exhibited the maximum hardness 30 Gpa in the same chamber. The TiAlN-coated BGA cut ter deposited at the optimized condition exhibited the twice longer life or higher machining speed in comparison with the ordinary one.
BP-30 Mechanical Properties and Oxidation Resistance of (Cr,Al)N Based Films Synthesized by Radio-Frequency Magnetron Sputtering Method H. Hasegawa, T. Miyake (Okayama University, Japan); S. Kunitsugu (Industrial Technology Center of Okayama Prefecture, Japan); K. Ohashi, S. Tsukamoto (Okayama University, Japan) Metastable nitride have been widely used in applications such as cutting tools, protection wear and machinery components, because of their superior tribological, chemical and physical properties. (Cr,Al)N has gained much attention as a substitute for (Ti,Al)N, and has been investigated with respect to, microstructure, mechanical properties, thermal stability, and cutting performance. Recently, we developed the newly (Cr,Al)N based films by adding foreign metal such as Y and Si, which are expected to lead formation of stable oxide and amorphous at elevated higher temperature. In this study, (Cr,Al,Y)N and (Cr,Al,Si)N were synthesized by radio-frequency magnetron sputtering method with differing N₂/Ar ratios. Microstructure and surface morphology is characterized by X-ray diffraction method, scanning probe microscopy and electron microscopy. Oxidation resistance was evaluated by thermo gravimetric analyzer with measurement of weight gain in dry air enviro nments. In addition, abrasive wear tests were conducted using a Calotest type apparatus. A rotating steel ball was pushed against the sample surface, and the wear volume was measured by a surface profiler.
BP-31 Tribological Characterisation of TiN_x Coatings Synthesized by Cathodic ARC Evaporation Technique J. Menghani, K.B. Pai, M.K. Totlani (SVNIT Surat, India); N. Jalgoankar (Multi-Arc India Ltd., India) Hard Ceramic coatings play continuously increasing grows in field of tribology as well as decorative applications. Stoichiometric titanium nitride (TiN) is actually one of the most important technological coating materials, not only because of its excellent tribological properties, but also due to its good chemical stability. It is certainly, in tribological terms, the most explored PVD hard thin film material and most extensively used in industry. It is used in a wide range of applications, which vary from protective material for machine parts and cutting tools to diffusion barriers in semiconductor technology]. In the past, properties of substoichiometric titanium nitride (TiN_x) have been studied by comparably few researchers. In the present investigation TiNx thin films of varying thickness (1.5 µm,2.0 µm ,2.5 µm , 3.0µm and 4.0 µm ) is deposited by Cathode arc evaporation technique. The compositional characterization was carried out by using Philips X-pert pro XRD, Wear testing was carried out using Pin on disc winducom testing machine, normal load applied was 5N,speed 500rpm and for 20 min. Microstructural analysis before and after wear testing was carried out using SEM(Hitachi 3400S).The effect of thickness on wear properties is discussed.
BP-32 NiTi Memory Alloy Sculptured Thin Film by Glancing Angle Electron Beam Evaporation Technique K. Kazmanli, L. Trabzon, M. Urgen, G. Gurluk (Istanbul Technical University, Turkey) In this study NiTi alloy sculptured thin films have been studied. The silicon wafer substrates were coated with NiTi alloy by electron beam deposition system. Because as-coated samples showed low crystal-formation, DSC investigation was conducted to find the crystal formation temperature of NiTi thin film. Crystal structure of the coatings was determined by means of X Ray Diffraction investigation. In order to produce films with different morphology (such as inclined, spiral and zig-zag column shapes), vapor flux angles and substrate rotation speed were changed systematically. All coatings were heat treated at the temperature determined from DSC investigation and characterized by using scanning electron microscope and ultra-micro-hardness tester.
BP-33 High Temperature Oxidation Resistance of Multicomponent Cr-Ti-Al-Si-N Coatings C.-Y. Hsiao, Y.-Y. Chang, D.-Y. Wang (Mingdao University, Taiwan); W. Wu (National Chung Hsing University, Taiwan) The high temperature oxidation resistance of the Ti-Al-Si-N and Cr-Ti-Al-Si-N coatings was studied. These coatings were deposited on silicon substrates by using a cathodic-arc deposition system with lateral rotating arc cathodes. Chromium, titanium and Al-Si alloy cathodes were used for the deposition of Cr-Ti-Al-Si-N coatings with different alloy contents. For the high temperature oxidation test, the coated samples were annealed between 700°C to 1000 °C in air. In this study, field emission scanning electron microscope (FESEM), transmission electron microscope(TEM) and X-ray diffraction(XRD) using Bragg-Brentano and glancing angle parallel beam geometries were used to characterize the microstructure of the as-deposited and annealed films. The composition and chemical bonding of the deposited and annealed Cr-Ti-Al-Si-N coatings were evaluated by X-ray photoelectron spectroscopy (XPS). The oxidation kinetics of the deposited coatings showed parabolic behavior, indicating that the diffusion process occurred during oxidation. It has been found that the high temperature oxidation behavior of the deposited films is correlated with the alloy content and nanocomposite structure. It indicated that the Cr-Ti-Al-Si-N with higher Cr, Al, and Si contents possessed superior oxidation resistance than Ti-Al-Si-N. The different oxidation mechanisms of the deposited Cr-Ti-Al-Si-N at high temperature will be developed.
BP-34 Optical, Morphological and Electrochemical Properties of Niobium Oxide Thin Films G. Ramírez, S.E. Rodil, S. Muhl (Universidad Nacional Autónoma de México); J.J. Olaya (Universidad Nacional de Colombia); M. Rivera (Universidd Nacional Autónoma de México); E. Camps, L. Escobar-Alarcon (Instituto Nacional de Investigaciones Nucleares, México) Niobium Oxide thin films were deposited by unbalanced reactive magnetron sputtering under different conditions of pressure and oxygen/argon flow ratio. The films were characterized to obtain their physical, structural, optical and electrochemical properties using X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), variable angle ellipsometry, nanoindentation ad atomic force microscopy. Combining the results of XRD and RBS, we can conclude that the films were amorphous having the Nb₂O₂5 stoichiometry. Although the pressure and O₂/Ar flow ratio were varied between 2 to 4 Pa and 1/10 to 3/10, respectively, no large changes in the film properties were obtained The mechanical and optical coatings did not show significant variations between the different deposition conditions; all the films were transparent with a bandgap about 3.4 eV and the hardness was around 4.5 Gpa. The morphology of films, measured with AFM, showed that the surface roughness varied between 0.6 to 2.9 nm, without any clear trend. Nevertheless, concerning the electrochemical properties, the response of the films to a DC polarization in a 0.85% NaCl solution was significant different. The parameters used to compare the electrochemical response were the polarization resistance and the corrosion resistance obtained from a Tafel Analysis.
BP-36 Effects of Low-Temperature Duplex Coatings on Corrosion Behavior of Austempered Ductile Iron C.-H. Hsu, C.-Y. Lee, K.-L. Chen, K.-C. Lu (Tatung University, Taiwan) Austempered ductile iron (ADI) is an attractive engineering material due to its excellent strength, toughness and the low cost. In general, the austempering is isothermally treated about in the temperature range from Ms to 450°C, thus the traditional surface modification of high temperature can not be available to treat ADI. This study utilized electroless nickel (EN) and cathodic arc deposition (CAD) technologies, with the known advantage of low processing temperature, to treat the ADI substrate. The eligibility of applying the EN and CAD-CrTiAlN duplex coatings on ADI, along with the coating properties, such as structure, roughness, and adhesion were evaluated and analyzed. Moreover, polarization tests were performed to further understand the effect of the coatings on the corrosion resistance of ADI. The results showed that the unique microstructure of ADI did not deteriorate after EN and CAD treatments. With regards to the corrosion resistance, the duplex coat ed specimens performed better than that of the uncoated and monolithic EN or CrTiAlN coated ones in 3.5 % NaCl aqueous solution.
BP-37 Thermal Evolution, Mechanical and Corrosion Properties of Al Implantation into TiSiN Nanocomposite Coatings by MPII Hybrid System C.-L. Chang, L.-Y. Tseng, C.-W. Wu, Y.-C. Liu, W.-Y. Lin (MingDao University, Taiwan) An as-deposited TiSiN film was post-treated with high-energy ion bombardment following the metal plasma ion implantation (MPII) process, involving an accelerated vacuum-arc metal plasma source with multiple charge states. In this study, the modification of the surfaces of energetic Al-implanted TiSiN films on the thermal evolution, mechanical and corrosion properties using metal plasma ion implantation (MPII) was investigated, by varying ion energy and dose. The microstructure and chemical states of aluminum, implanted on the surface layer of TiSiN films, were examined, as functions of ion energy and dose, by nanoindenter, Auger electron spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. TiSiN and Al-implanted TiSiN coated samples were oxidized in air using a conventional furnace at different temperature for 2 h. The phase transformations and surface morphology of coatings were observed by utilizing X-ray diffractometer and AFM. The corrosion behavior of coatings was investigated using polarization and immersion tests. Polarization test of coatings was carried out in the solution of 3.5 wt.% NaCl. For immersion test, the coatings were exposed under H₂SO₄ environment for 24 h. The results turned out that better thermal evolution, mechanical properties and corrosion resistance of Al-implanted TiSiN coatings than that of TiSiN, which can be enhanced by Al implantation using MPII method.
BP-38 Using High Work Function Ni Metal to Improve the Stress Reliability of CaCu₃Ti₄O₁₂ MIM Capacitors L.-C. Chang (Mingchi University of Technology, Taiwan); C.-H. Yang, H.-L. Kao (Chang Gung University, Taiwan); F.B. Wu (National United University, Taiwan) The RF sputtered CaCu₃Ti₄O₁₂ (CCTO) MIM capacitors were fabricated at 400°C using low-cost and high-work function Ni electrode to improve leakage current for VLSI backend integration. This stress degradation is especially a concern in CCTO materials, which also leads to high leakage currents because of the small conduction band discontinuity (δΕ_C) with respect to Si. We report improvements in the thermal leakage current by using Ni as a high-work-function top electrode for CCTO capacitors. This avoids sacrificing the overall value by using a multilayer or laminate structure and results in better voltage linearity, which is important for memory integrated circuits. Here we describe the stress reliability of the nonvolatile memory characteristics of hi-κ MIM capacitors.
BP-40 Phase Transformation, Thermal Stability and Indentation Behavior of Ni-P-Based Interlayer Enhanced CrN Composite Coatings Y.Y. Li, Y.C. Hsiao, J.C. Wu, F.B. Wu (National United University, Taiwan) In present study, CrN/NiP and CrN/NiPAl composite coatings were fabricated by magnetron sputtering technique. The sputtering of Ni-P-based interlayers was fulfilled by the electroplating of patterned Ni-P thick films on Cu and Al disc substrates. The microstructure of the duplex coatings was controlled by the process temperature during sputtering and post annealing procedures. According to phase identification, the CrN coating was successfully deposited under process temperature from 350 to 550°C. A preferred CrN(200) orientation was observed for the CrN coating deposited on the NiP binary alloy interlayer under 350°C process temperature. The diminishing of the preferred orientation of CrN coating was accompanied by the phase transformation of the NiP layer as the deposition temperature was increased. On the contrary, the amorphous phase of the NiPAl interlayer retained until process temperature was raised to 450°C and no significant related preferr ed orientation was found for the CrN layer. It was believed the introduction of Al in NiP not only increase the thermal stability of the duplex coating, but improve the thermal resistance during CrN coating deposition. In addition, through loading-unloading nanoindentation analysis, significant creep behavior was observed when the microstructure of the interlayer was amorphous or fully crystallized. With adequate heat treatment, the creep of the composite coatings could be reduced by the precipitation and crystallization of the Ni-P-based interlayer.
BP-41 Superhard Coatings Prepared by Pulsed Magnetron Sputtering M. Keunecke, K. Weigel, K. Bewilogua (Fraunhofer Institute for Surface Engineering and Thin Films, Germany); W. Kölker, P. Jaschinski (Cemecon AG, Germany) Hard coatings like TiN, TiAlN, titanium diboride or boron carbide are in use as hard and wear resistant tool coatings. These coatings often will be prepared by PVD techniques like arc evaporation or d.c. magnetron sputtering. Typical micro hardness values of such hard coatings deposited with d.c. magnetron sputter are more or less in the range of 30 GPa. As a clear advancement compared to d.c. magnetron sputtering processes the pulsed magnetron sputter deposition technique could be verified. Different hard coatings were prepared using the pulsed magnetron sputter technique in a CC800/9 batch coater equipped with 4 targets. Coatings prepared with the pulsed sputter process showed a significant increase in hardness. The highest hardness values were reproducibly measured with up to 50 GPa. Beside the hardness other mechanical properties like resistance against abrasive wear and adhesion were measured. Cross sectional SEM images showed the growth structure of the coatings. The chemical composition of the coatings was investigated by microprobe measurements. It could be stated that with a pulsed magnetron sputter process the property range of the hard coatings could be extended especially with respect to the hardness reaching for some coatings even the superhard (> 4000 HV) region.
BP-43 Evaluation of the Electrochemical Behaviour of Tantalum Oxide Thin Fims for Biomedical Applications P.N. Rojas, S. Muhl, S.E. Rodil (Universidad Nacional Autónoma de México) The corrosion resistance of materials in the body fluids is an essential factor to determine the lifetime of medical implants. Tantalum oxide films were deposited on medical grade stainless steel using an rf-magnetron sputtering system working at three different powers (50, 150 and 200 W) and different working pressures (0.67, 2, 4 Pa) These films were evaluated using Potentiodynamic polarization (PP) in 0.89% NaCl (7.4 pH) in order to determine the conditions that lead to the best corrosion resistance. The effect of the deposition conditions on the film physical properties was also evaluated by means of electron microscopy, energy dispersive analysis, ultraviolet-visible spectroscopy, ellipsometry and infrared spectroscopy and correlated to the electrochemical parameters. Based on these results, one single deposition condition was chosen to make a further evaluation by electrochemical impedance spectroscopy (EIS) and Potentiodynamic polarization using three simulated body fluids; 0.89% NaCl solution, Hartman (ringers-lactate) and Gey´s solution, as a function of the immersion time.
BP-44 Microstructure and Properties of Laser-Cladded Cr-Ni Coatings Prepared on Steel A. Iwaniak, E. Augustyn, J. Adamiec (The Silesian University of Technology, Poland) This article will be presents results of microstructural investigation and properties characterization of Ni-Cr coatings deposited on carbon steel by flame spraying and diode laser cladding processes. Ni-Cr coatings were deposited on steel substrates by flame spraying using of commercial powders Metco, next was cladding by using 2kW diode laser. The phases of clad layer were investigated by an optical microscope, scanning electron microscopy (SEM), X-ray diffractometer (XRD), electron probe microanalysis (EPMA) and energy-dispersive spectrometer (EDS). If proper cladding parameters are used, the clad layers will have a good surface shape, sound metallurgical bonding with base metal, low dilution, and the effect of heating on heat-affected zone metal can be limited. A clear dependence of the micro-cracking susceptibility on the base preheating temperature is observed for Ni-Cr coatings prepared by direct laser melting on the preheated steel. The number of cracks decreas es with the preheating temperature and for preheating for 300°C no cracks are observed. It was found that the laser cladded zone has a higher microhardness value compared with that of the flame spraying treated material. This is a result of the significant reduction in grain size in the case of laser cladding. Unlike the flame spraying cladded zones, the laser treated material is free of micropores and microcracks.
BP-45 Development of Temperature Sensor Thin Films to Monitor Turning Processes W. Tillmann, E. Vogli (TU Dortmund University, Germany); K. Pantke, D Biermann (Institute of Machining Technology, Germany) Increasing demands on the chipping process require a fundamental analysis concerning the design as well as the material selection for cutting insert and its wear protection. By employment of novel wear resistance thin coatings the cutting inserts can be effectively protected from wear. Apart from the monitoring the wear and the cutting forces the knowledge of the developed temperatures during cutting process is essential and necessary. In this work an innovative technology was employed to measure in-situ the temperature development during cutting process. The measurement was based on the Seebeck-effect. Coating adhesion was systematically analyzed and optimized by varying of pretreatment conditions. Furthermore the design of masks was enhanced and finally turning experiments were carried out to scrutinize the efficiency of deposited temperature sensors in cutting tests.
BP-46 Why a TiN Coating is not Suitable for Corrosion Protection of Steel J.P.M. Groenewegen, R. Machunze, G.C.A.M. Janssen (TU Delft, Netherlands) Titanium nitride (TiN) is a hard coating well known for its excellent hardness and wear protective properties. Many studies have found that TiN is hardly useful for corrosion protection of steel. In order to find the cause for this absence of corrosion protection we did measurements on TiN coatings on steel and on glass. We prepared two series of samples, TiN on glass, and TiN on steel. Thin TiN films (18 - 2000 nm) are deposited by reactive unbalanced magnetron sputtering on glass slides and hot working tool steel substrates, using an industrial setup. During deposition (dep. rate approx. 0.1nm/s) at 5kW power, 125V bias voltage, 450°C dep. temperature and 4x10^-3mbar pressure, the samples performed a planetary motion in front of the Ti target (target size 600x120mm²). We first measured the open potential of TiN on glass to compare the corrosion properties of TiN with those of tool steel. From this measurement we conclude that TiN provides anodic protection, i.e. through coverage only. The corrosion current of TiN on glass was found to be orders of magnitude lower than that of steel. Therefore it is likely hat corrosion of the steel starts at defects in the coating. The coatings showed defects, some related to the deposition process, some related to the substrate. Corrosion experiments, performed while observing the coating through an optical microscope, indeed showed that corrosion of the steel starts at defects in the coating. Microscopy on the substrates before deposition showed some porosity in the surface of the polished steel samples. It was found that these defects in the steel substrate are not covered by a continuous TiN film during deposition. Therefore, even if the deposition related defects are eliminated, TiN is not a suitable coating for corrosion protection due to the porosity of the steel.
BP-47 Raman Spectroscopy as a Tool to Study Composition in Cubic Ti-C-N CVD Coatings I. Dreiling, A. Haug (University of Tuebingen, Germany); H. Holzschuh (Walter AG, Germany); T. Chasse (University of Tuebingen, Germany) A series of CVD TiC_nxN_ny coatings (x: 0-1; x+y=1) was deposited on cemented carbide. These coatings were characterized using Laser Raman spectroscopy. Even small changes in C/N ratio resulted in significant Raman shifts. However, effects of Laser power have to be taken into account carefully. Raman spectroscopy has been shown to be a very useful non-destructive tool to characterize the composition of CVD coatings.

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