ICMCTF2002 Session FP-1: Symposium F Poster Session

Tuesday, April 23, 2002 5:00 PM in Room Town & Country

Tuesday Afternoon

Time Period TuP Sessions | Topic F Sessions | Time Periods | Topics | ICMCTF2002 Schedule

FP-1-2 Surface Characteristics of Electroless and Sputtered Ni-P-W Alloy Coatings Y.Y. Tsai (Industrial Technology Research Institute, Taiwan); F.B. Wu, S.K. Tien, J.G. Duh (National Tsing Hua University, Taiwan, ROC) The ternary Ni-P-W coatings are fabricated by two kinds of deposition techniques, including the electroless plating and RF magnetron sputtering, which are categorized as chemical and physical deposition methods, respectively, for functional and protective thin film. Surface morphologies and roughness of the coatings are investigated in a wide range from millimeter down to nano-scale to probe surface characteristics of coatings. Various characterization methods are employed, including optical, scanning electronic, atomic force microscopy, and alpha-step profile analysis. The surface roughness of the electroless platings are measured to be in the range of tens nanometer while that of the sputtered coatings are an order less. It is found that the nodular geometry nature of the electroless plating observed by microscopy is responsible for the rougher surface profile as compared to the sputtered coatings. Factors including addition element, deposition rate, and thermal history are also discussed. After thermal annealing at 400°C and 450°C, there is no appreciable variation in the surface roughness for both electroless plated and sputtered Ni-P-W coatings.
FP-1-3 Study of Chromium Nitride Films Seposited by IBAD, Magnetron and Triode Sputtering Techniques C. Nouveau, M.A. Djouadi, A. Vasin, P. Beer (ENSAM, France) Previous studies showed that chromium nitride layers deposited by magnetron and triode sputtering techniques permit to increase the service life of cutting tools in wood machining [1]. Nevertheless, the adhesion of the coatings was not sufficient and the wear of the tools was too high. It is well known that Ion Beam Assisted Deposition technique (IBAD) improved in a significant manner the adhesion of the films by the use of a higher level of ion bombardment. So, CrN and Cr₂N films have been deposited by IBAD technique on silicon, low alloy steels, high speed steels and cemented carbide inserts. After composition (EDS and EPMA), structural (XRD and SEM), mechanical (stress measurements) and tribological (nanohardness) characterization of the coatings, optimal coatings were chosen. Knives were coated and applied in wood cutting process. The results of this exploratory work will be presented and a comparison between the films obtained by the three methods will be made. [1]M.A. Djouadi, C. Nouveau, P. Beer, M. Lambertin, "Cr_xN hard coatings deposited by PVD method on tools for wood machining", Surface and Coatings Technology 133-134 (2000) 478-483.
FP-1-4 The Outgassing Characteristics of MgO Film for Protecting Layer in Plasma Display Panel B.K. Song, Y.J. Lee, K.N. Kim (Sungkyunkwan University, Korea) Plasma display panel(PDP) is one of the most promising candidates for large-area wall hanging displays, because of simple panel structure, easy and cheap processes appropriate for large area displays, good display quality, and high speed addressing ability. However, impurities such as H₂, H₂O, N₂, CO₂, and O₂ inside the discharge cells remaining during the processing may deteriorate the characteristics of PDP and reduce the operation lifetime of PDP. MgO film is used to protect the dielectric layer in AC PDP and it is known to be the main source of those impurities. In this study, outgassing characteristics of MgO films deposited by various methods have been investigated. The MgO films were fabricated by e-beam evaporation, sputtering, and IBAD(Ion Beam Assisted deposition). Also, the effects of plasma cleaning of the deposited MgO by inductively coupled plasma and atmospheric pressure equipment on outgassing rate were compared. The MgO layer deposited by various methods were heated up to 350° and kept at this temperature over 4 hours to investigate the outgassing characteristics at the heated condition. The outgassing measurement chamber was consisted of a halogen lamp heating system pumped by a turbomolecular pump and a quadrupole mass spectrometer (PSM501, Hiden Analytical) was connected to this chamber. Mass spectrometric measurements at 350° have shown that the outgassing rate is primarily related the MgO with species of H₂, H₂O, N₂, CO₂, and O₂ is the main outgassing species released by MgO.
FP-1-5 Ion Beam Analysis of Ti/TiN Multilayers and the Corresponding Interfaces L. Huerta, M. Flores, S. Muhl (Instituto de Investigaciones en Materiales, UNAM, México); R. Alfaro (Instituto de Fisica, UNAM, México) Multilayer films of TiN/Ti have been prepared on H13 steel substrates by reactive magnetron sputtering with a variable applied magnetic field. The multilayers were prepared using different and uniform periods, and with various thicknesses of the top layer. The first layer was always titanium. The change from Ti to TiN deposition was achieved by controlling the nitrogen flow without plasma interruption, so that a graded interface was generated. Ion beam analysis was used to determine the composition and the characteristics of the interfaces between the different layers. The Rutherford Back Scattering (RBS) of the ¹⁴N(alfa, alfa)¹⁴N and ²²Ti (alfa, alfa)²²Ti sections at 3.1 and 7 MeV were used to analyze the composition of the films. It was found that the interface between the TiN and Ti (when the N₂ was interrupted) is more extended than that between the Ti and TiN. 13.
FP-1-6 A Study on Chromium Carbide Synthesized by 90°-bend Magnetic Filtered Cathodic Arc Evaporation C.-C. Lin, J.H. Lin, P.-S. Shih, H.C. Shih (National Tsing Hua University, Taiwan, ROC) In general, macro-particle contamination is higher in the deposition of metal films from unfiltered sources and high quality layers can only be produced from filtered sources. In this study, we prepared Cr_xC_y films using the 90°¡Vbend magnetic filtered cathodic arc evaporation (FCAE) plasma system on both M2 and 304 steel, and the films were synthesized reactively from Cr target and C₂ H₂ reactive gas. Microstructure and surface morphology are analyzed using scanning electron microscopy (SEM), the phase and concentration profiles of Cr_xC_y films evaluated by X-ray diffraction (XRD) and Auger electron spectroscopy (AES). In addition, the compsition and chemical state of the Cr_xC_y flims were assessed by ESCA spectrum. The determination of the adhesion strength of the deposit on both substrate was assessed by scratch test. In summary, we found ion bombardment with Ar on steel substrate is an important process toward better Cr_xC_y flims.
FP-1-7 Phase Transformation in Chromium Nitride Films H.-Y. Chen, F.-H. Lu (National Chung Hsing University, Taiwan, ROC) The phase transformation of CrN films prepared on Si substrates by cathodic arc plasma deposition was investigated at various temperatures using XRD and stress measurements. The films were annealed in N₂/H₂=9 reducing atmosphere over the temperature range 400-1200°C. XRD results showed Cr₂N phase appeared both at temperatures higher than 1100°C and at 500-700°C. The formation of Cr₂N at high temperatures above 1100°C can be explained by thermodynamics. The residual stress in the films relaxed largely over the temperature range 500-700°C at which Cr₂N was formed. Moreover, Cr₂N phase would not occur at such a temperature range when the films were pre-annealed at high temperature. The formation of Cr₂N at such low temperatures is mainly due to large stress relaxation in the films. The stress states of the films at different pre-annealing conditions have been measured and correlated to the phase transformation of the films.
FP-1-8 Influence of Oxygen Partial Pressure on Titanium Oxide Formation by Vacuum Arc Plasma Deposition Y.X. Leng, N. Huang (Southwest Jiaotong University, China); P. Yang (City University of Hong Kong); J.Y. Chen, H. Sun, J Wang, G.J. Wan (Southwest Jiaotong University, China); Y. Leng (Hong Kong University of Science & Technology); P.K. Chu (City University of Hong Kong) Titanium oxide thin films are widely used due to their outstanding optical, electrical, and chemical properties. There are three kinds of crystalline phases: anatase, rutile and brookite. The rutile structure has superior optical properties and blood compatibility, and is thermodynamically more stable than the others. Thus, the formation of TiO₂ films with the rutile structure is of interests to materials researchers. In this work, titanium oxide thin films are deposited on (100) silicon and SiO₂ wafers by vacuum arc plasma deposition using a DC bias. The influence of the oxygen partial pressure on the properties of the coatings is investigated. The XRD results show that there are Ti₇O₁₀ or Ti₄O₇ phases in the films when the oxygen partial pressure is lower than 2.0 - 10-2 Pa. As the oxygen partials pressure increases, the preferred orientation of the as-deposited titanium oxide film changes to the (200) high-index plane from the (100) low-index plane. The as-deposited titanium oxide films are subsequently annealed at 700°C for 30min or 750°C for 30min in vacuum. The microstructure, resistance, composition, and blood compatibility of all the films are studied. As the oxygen partial pressure increases, the sheet resistance of as-deposited titanium oxide film goes up and increases by 10 to 100 times after annealing.
FP-1-9 Structure and Properties of WC - CrAlN Superlattice Film by Cathodic Arc Ion Plating Process H.Y. Lee, J.G. Han, S.H. Baeg, S.H. Yang (Sungkyunkwan University, Korea) In recent years, great attention has been devoted to the development of a new class of thin films with a special structure and unique properties. Superlattice and nanocomposite coatings belong to this class of new thin film. Properties of Superlattice and nanocomposite, which have superhard as well as wear resistance and good thermal stability, have developed by the control of elements forming and process parameters for film deposition. In previous works, new superlattice film of WC - CrN was developed in our laboratory. The microhardness of WC - CrN films was measured to be in the range of 30 ~ 40Gpa. Also, as a result of oxidation resistance, WC - CrN superlattice film was proved about three times better than CrN film. In this study, WC - CrAlN superlattice film was deposited on Si wafer and S45C steel substrate by cathodic arc ion plating process for wear and oxidation resistance. Al concentration and bilayer repeat period( ?) was controlled to obtain a nano - layered structure. We have characterized using X - ray diffraction (XRD), cross - sectional TEM and electron diffraction pattern. Mechanical properties of WC - CrAlN film were evaluated by microhardness, residual stress and scratch test. Our preliminary results indicated that the microhardness of this film was evaluated up to 30Gpa. Moreover the structure of WC - CrAlN film was transformed from a dense columnar structure to nanocomposite one. This detailed study will be presented.
FP-1-10 Structural Modifications and Phase Formation in CdTe Oxide Films Grown by RF Reactive Sputtering F. Caballero-Briones, A. Iribarren, M. Zapata-Torres, O Calzadilla, J.L. Peña-Chapa, A. Zapata-Navarro (CICATA-IPN Unidad Altamira, Mexico) In this paper our aim was to obtain crystalline, highly oxidized CdTe films by RF reactive sputtering in Ar-N₂O plasma. We varied the substrate temperature, the plasma power and the N₂O partial pressure. DC Bias mode was used to regulate the plasma power, giving a more stable plasma. Film colors varied from dark gray to transparent with increasing N₂O partial pressure and decreasing plasma powers. Films were studied by X-ray diffraction in order to assess the structural evolution and phase formation depending on the growing parameters. We found that films tend to be a mixture between the CdTe cubic and hexagonal phases when low N₂O pressures and high substrate temperatures are used, but cubic CdTe was found in transparent films grown with high plasma power and high N₂O pressure. Changes in the preferential orientation and phase concentration were calculated and related with deposition parameters. When N₂O pressure increases, films tend to be amorphous but different amorphous halos are obtained depending on the plasma power and substrate temperature. A crystalline phase related with CdTeO₃ was obtained when high N₂O pressures, low plasma power and high substrate temperature was used.
FP-1-11 Influence of Deposition Conditions on the Properties of Tungsten Sputtered Coatings A. Monteiro, V. Teixeira (Universidade do Minho, Portugal); F. Guimaraes (Institute of Materials, Portugal); F. Silva (Instituto Politecnico do Porto, Portugal); A.P.M. Baptista (Universidade do Porto, Portugal); E. Pereira (Universidade de Aveiro, Portugal) With the aim to develop PVD interlayers to grow thick diamond CVD coatings on steel for mechanical applications we have sputtered tungsten coatings, among other materials (Si, Ti, etc.). In this paper structural, electrical, optical and mechanical properties of tungsten coating deposited by DC magnetron sputtering were studied as function of argon pressure, applied bias voltage, deposition time, and temperature. W-coatings were deposited on glass, copper and stainless steel from a pure W-target, in argon atmosphere. The crystallographic structure and composition were investigated by x-ray diffraction (XRD). Scanning Electronic Microscopy (SEM) analyze the film thickness and superficial defects. The coatings sheet resistance was analyzed by four-point probe method. Atomic Force Microscopy (AFM) was used for microtopography investigations. Optical properties were study by reflectance spectrophotometer spectra. Residual stresses are key concept to develop feasible interlayers for deposition of CVD diamond coatings. The in-plane coating residual stress was study by means of a micro-displacement laser transducer for different deposition conditions. X-ray analyses can be selected to determine the film phase. Optical and electrical analyses have a directly relation with argon gas pressure, and they have similar behaviour. The results indicate that tungsten coatings properties can be controlled by argon gas pressure, applied voltage, deposition time, and temperature. Films with different phases (W, b-W and a W+b-W mixture), optical reflectance (between 68 and 31%), electrical conductivity (between 26 and 3500µmΩ.cm), and stress (compressive or tensile) can be obtained changing the sputtering parameters.
FP-1-12 Physical and Morphologycal Characterization of Reactively Magnetron Sputtered TiN Films F. Vaz, L. Cunha, L. Rebouta, J. Mendes, S. Lanceros-Mendez, P. Machado, S.M.C. Nascimento, A. Sidor (Universidade do Minho, Portugal); K. Pischow, J. de Rijk (Savcor Coatings Oy, Finland) The present paper reports on the influence of preparation conditions: i) power applied at the Ti target and, ii) bias voltage, on the properties of TiN thin films deposited by r.f. reactive magnetron sputtering in the low-pressure range. The ion bombardment was obtained by d.c. biasing of the substrates in the range of 0 (grounded) to -150 V. The deposition rate varied between 0.4 and 1.5 µm/h, depending on the deposition parameters. SEM images show columnar-type structure, lying in the T and I zones of Thornton Model. Higher ion bombardment increases the density of the films. There is a preferred orientation of {111} planes parallel to surface, but decreasing the applied power on Ti target or increasing substrate bias favour the texture effect in the films. The electrical resistivity varies between 40 and 50 mΩcm for most of the films, but those deposited with the highest applied power or with grounded substrate show significantly higher values (between 85 and 100 mΩcm). The colour of the films surface was analysed on the basis of the Lab* colour system and related with deposition conditions.
FP-1-13 Properties of Polysilicon Films Using Grid-assisting Magnetron Sputtering M.J. Jung, Yun M. Chung, J.G. Han (Sung Kyun Kwan University, Korea) Polycrystalline Si thin film is widely applied materials for thin film transistor of Flat Panel Display (FPD), and photovoltaic applications because of its high mobility, electrical conductivity, and high-energy conversion efficiency compared to a-Si. Over the past few years, there have been a variety of techniques on thin film growth of poly-Si. Among theses techniques, Solid Phase Crystallization (SPC) and Excimer Laser Annealing (ELA) have been the most frequently used methods. The SPC method has too high crystallization temperature ( >> 650centi degree) for glass substrate. On the other hand, ELA method is suitable for low temperature on the glass substrate, however, there are still problems such as non-uniformity of grain growth on the large area glass substrate as well as expensive processing cost. Recently, Metal-Induced Crystallization (MIC) of amorphous silicon has been studied for poly-Si thin films on glass. We have deposited crystalline poly-Si thin films on glass substrate by magnetron sputtering method without grid. The electron mobility of the poly-Si grown on glass at substrate temperature of 500centi degree show 42 square centimeter/V sec. It is well known that thin film growth can substantially be modified by ion-bombardment during the deposition. An attractive way to promote crystalline growth at low temperature is deposition of additional energy in to the surface of the growing film by bombardment with hyperthermal particles. Therefore, to investigate film microstructure as well as the nucleation and growth mechanism of poly-Si thin film as the attached grid, poly-Si were deposited on glass with target power density by magnetron sputtering. In addition, we have studied the variation of plasma state for the feed back control of nucleation and growth mechanism by Langmuir probe. The microstructual characteristics and surface properties of the films were analyzed by TEM, XRD, and AFM.
FP-1-14 Optical Emission Spectroscopy Study of a rf Magnetron Sputtering Discharge Used for Multilayers Thin Film Deposition L.A. Carvajal Ospina, G. Zambrano, Unknown Prieto (Universidad del Valle, Colombia); E. Restrepo, A. Devia (Universidad Nacional-Seccional Manizales, Colombia); C. Rincon (Universidad Autonoma de Occidente, Cali, Colombia) An investigation by Optical Emission Spectroscopy (OES) was performed on a RF (13.56 MHz) magnetron sputtering discharge used for Tungsten Carbide/ Diamond-Like Carbon (W-C/DLC) multilayers thin film deposition. The multilayers deposition is obtained starting from a single tungsten (99.99%) and carbon (99.99%) binary compound target by gradual variation of methane (CH₄) concentration in the Argon/ Methane (Ar-CH₄) gas mixture. Measurements of optical emission spectra are performed to control the plasma discharge during the deposition process in order to analyze the state of the chemical species in the plasma. The dependence on RF power, gas pressure and methane concentration in Ar-CH₄ gas mixture of some Ar , W, and H emission line intensities, electron density and temperature are studied in the center of the discharge. A simple model for the excitation process of the Ar, W, C and H atoms allows us to calculate the density of sputtered atoms in the plasma. At high methane concentrations for deposition of DLC layers, OES shows that besides of the atomic hydrogen peaks H_α (656.3 nanometer) and H_β (486.1 nanometer) of Balmer Series, emission spectra are dominated by neutral CH specie and the most intense peak in the spectra correspond to CH band head at 431.5 nanometer which is supposed to be the precursor species in the diamond-like films. Owing to the transport regime of the W and C sputtered species across the discharge, the existence of a correlation between the target composition, tungsten density in the plasma and the multilayer thin film composition and microstructure determinate by XPS, XRD, IR and Raman spectroscopy were studied.
FP-1-15 Preparation of Fe₅₀Mn₅₀ Films by Facing Targets Sputtering with Plasma Exposure T. Takahashi, N. Sasai, K. Masugata (Toyama University, Japan) FeMn films have been previously used for antiferromagnetic layer of spin-valve devices. However, when these films apply to such a layer, it is necessary to prepare films with γ-FeMn(111) plane parallel to the film plane. It is very difficult to obtain γ-FeMn because its phase only appears at high temperature region. So, such FeMn films can be prepared under the conditions exposed with plasma and bombarded with high energy particles in sputtering. In sputtered films, it is very important to investigate the influence of plasma exposure to the substrate because the properties of films strongly depend on the plasma state. So, in this study, Fe₅₀Mn₅₀ films have been deposited at different substrate positions using the facing targets sputtering which can easily vary the degree of plasma exposure. Fe₅₀Mn₅₀ films with thickness of 500-1000 nm were deposited on glass-slide substrates. The crystal structure of films was measured using an X-ray diffractometry. When Fe₅₀Mn₅₀ films were deposited at the position most separate from the plasma, the γ-FeMn(111) peaks were observed from the X-ray diffraction pattern. As the substrate approaches the plasma, X-ray peak intensity of γ-FeMn(111) gradually decreased. This intensity significantly depended on the substrate position in this study. With further approach of substrate to the plasma, γ-FeMn(111) peak was not found but peaks of α-FeMn(411) and α-FeMn(330) were observed in behalf of γ-FeMn(111) peak. This implied that FeMn films with good crystal orientation have been deposited under the condition of plasma free. Consequently, it was found that crystal structure of Fe₅₀Mn₅₀ films were strongly affected to plasma exposure during film deposition.
FP-1-17 Dependence of Working Gas Pressure and Ratio of Ar to O₂ on Properties of TiO₂ Films Deposited by Facing Targets Sputtering T. Takahashi, N. Nakabayashi, K. Masugata (Toyama University, Japan) In reactive sputtering, it is very important to investigate the influences of bombardment of energetic particles and incidence energy of sputtered atoms to the substrate because this leads to the interesting effects such as enhancement of reactivity, adatom mobility and atomic peening. Therefore, the properties of films may significantly depend on the bombardment condition. So, in this study, TiO₂ films with thickness of 2000-3000 nm have been deposited on glass-slide substrates at various working gas pressure P_W and an atmosphere of Ar and O₂ mixture, using the facing targets sputtering. All TiO₂ films deposited in this study showed transparent and have smooth surface. In TiO₂ films deposited at P_W of 3 mTorr and Ar flow rate R_Ar of 30 ccm and O₂ flow rate R_O of 5 ccm, the small diffraction lines of the A(101), A(112), A(211) and A(220) peaks were observed from the X-ray diffraction patterns, where A shows an anatase of TiO₂. On the other hand, when deposited at P_W of 1 mTorr and R_Ar of 10 ccm and R_O of 5 ccm, the most preferential film with strong peak of A(101) was obtained. The (101) lattice plane of the crystallites is mostly parallel to the substrate plane. The crystallinity of them highly improved with decreasing P_W and R_Ar/R_O. Moreover, All of TiO₂ films deposited in this study also showed anatase from the Raman spectra with Raman shift of 145 cm^-1. The transmittances of TiO₂ films have a constant value of 80-90 % at wavelength in the range of 900 nm to 380 nm. At wavelength less than 380 nm, the transmittance abruptly decreased to zero. Consequently, it was found that the crystal orientation of TiO₂ films strongly affected to the bombardment of energetic particles to the growing film and incident energy of sputtered atoms.
FP-1-18 The N₂O Plasma Treatment to Low-k Organosilicate Glass (OSG) Against Dielectric Damage During Photoresist Removal Process. T.C. Chang (National Sun Yat-Sen University, Taiwan, ROC); Y.S. Mor, T.M. Tsai, C.W. Chen (National Chiao Tung University, Taiwan, ROC); Y.J. Mei (Ching-Yun Institute of Technology, Taiwan, ROC); S.M. Sze (National Chiao Tung University, Taiwan, ROC) The impact of O₂ plasma and chemical wet stripper on the quality of organosilicate glass (OSG) is investigated in this work. Photoresist removal is the indispensable process in integrated circuit fabrication. O₂ plasma ashing and wet stripper dipping are conventionally performed to remove organic photoresister. However, OSG will be damaged after photoresist removal process. O₂ plasma and wet stripper will attack function groups and generate dangling bonds in OSG film. The dangling bonds will easily convert into Si-OH bonds and induce moisture uptake. This will result in the increase of leakage current and dielectric constant. As a result, dielectric degradation will occur in OSG film after photoresister removal. N₂O plasma treatment to OSG is performed in order to prevent photoresisit stripping damage. N₂O plasma treatment can passivate OSG surface and prevent Si-OH bonds formation so that moisture uptake can be reduced in the OSG film. Consequently, the leakage current will be decreased and the dielectric constant can be maintained at a low-k value even after OSG undergoes photoresist stripping process. Therefore, N₂O plasma treatment is an effective technique to enhance the resistance of OSG film to photoresist stripping damage.
FP-1-19 Eliminating Dielectric Degradation of Low-k Hybird-Organic-Siloxane-Polymer (HOSP) During Photoresist Removal Process T.C. Chang (National Sun Yat-Sen University, Taiwan, ROC); T.M. Tsai, Y.S. Mor, C.W. Chen (National Chiao Tung University, Taiwan, ROC); Y.J. Mei (Ching-Yun Institute of Technology, Taiwan, ROC); T.Y. Tseng (National Chiao Tung University) The interaction between low-k Hybird-Organic-Siloxane-Polymer (HOSP) and photoresist (PR) stripping is investigated in this study. O₂ plasma ashing and chemical wet stripping are commonly performed to remove photoresist (PR) in the integrated circuit fabrication. However, O₂ plasma or wet stripper attack will cause dielectric degradation in HOSP films during PR removal processing. The dielectric degradation is due to Si-OH bonds formation. Si-OH bond can induce moisture uptake in the damaged HOSP films so that leakage current and dielectric constant will be increased. Hexamethyldisilazane (HMDS) treatment is proposed in order to eliminate dielectric loss in the damaged HOSP film. Chemical HMDS, (CH₃)₃Si-NH-Si(CH₃)₃, can react with Si-OH bonds and convert Si-OH bonds into Si-OSi(CH₃)₃ bonds in HOSP films. The Si(CH₃)₃ bonds are hydrophobic and consequently HOSP surface can be converted more hydrophobic by HMDS treatment. The hydrophobic surface will reduce the moisture uptake. For this reason, the leakage current and the dielectric constant can be decreased significantly after damaged HOSP films undergo HMDS treatment. Therefore, HMDS treatment is a promising method to apply to the photoresist removal process.
FP-1-20 Duplex Treatment Based on the Combination of Ion Nitriding and PVD Process:Application in Wood Machining C. Nouveau, M.A. Djouadi (ENSAM, France); P. Beer (Warsaw Agricultural University, Poland); P. Jacquet (ENSAM, France); L. Imhoff (University of Burgundy, France); M. Lambertin (ENSAM, France) In the present work, the nitridation of low alloy steel knives (60SMD8) was optimised by testing steel knives, nitrided at different temperatures, in peeling of MDF (Medium Density Fiberboard). Such optimal nitrided knives were CrN, Cr₂N and Cr₂N/CrN-coated, on both faces, by magnetron sputtering and tested in peeling of MDF and beech wood. While the nitridation process permits to increase the wear resistance of the non treated steel knives, the CrN duplex treatment shows the best performances during peeling of both kind of wood thanks to the coatings properties and also to the nitridation process. Indeed, it appears that the nitridation of the knives before coatings increases the adhesion of the deposited films.
FP-1-22 X-ray Residual Stress Measurements of CdTe Nanocrystals Dispersed in TiO₂ Matrix S. Kohli (Colorado State University); S.N. Sharma (National Physical Laboratory, New Delhi, India); C.D. Rithner (Colorado State University); A.C. Rastogi (National Physical Laboratory, Hew Delhi, India); P.K. Dorhout (Colorado State University) Size dependent physical, optical, chemical, electrical properties of semiconductor nanocrystallites had been a subject of extensive study. Semiconductor nanocrystals dispersed in wide band gap material are not only being studied for the understanding of the basic quantum confinement phenomena exhibited by these materials, but also for their possible application in the futuristic electro-optic devices ¹. In the past we had investigated the structural, optical and electrical properties of CdTe nanocrystallites dispersed in TiO ₂^2,3and SiO2 matrix ⁴. In the present paper we will be reporting the residual stress analysis of the 0.5µm r.f. sputter deposited CdTe: TiO₂ composite films. The residual stress measurements performed using conventional Sin²ψ method will be reported and complete stress tensor will be evaluated footnote5,6. Data from Glancing Angle XRD (GAXRD), X-ray Photoelectron Spectroscopy (XPS) and Spectroscopic Ellipsometry will also be reported. Variation in the residual stress as a function of crystallite size will be reported and the data will be correlated with other structural and optical properties. ¹D.D. Beck and R.W. Siegel, J. Mater. Res. 7 (1992) 2840 . ²A C. Rastogi, S. N. Sharma and Sandeep Kohli, Semicond. Sci. Techno. 15 (2000)1011. ³A. C. Rastogi, S. N. Sharma and Sandeep Kohli, Mat. Res. Soc. Symp. Proc. 536 (1999)263 ⁴Sandeep Kohli, S.N. Sharma and A.C. Rastogi, Proc. of the Tenth International Workshop on the Physics of Semicondcutor Devices, Eds. V. Kumar and S.K. Aggarwal, SSPL New Delhi, India (1999). ⁵ Sandeep Kohli, C. D. Rithner and P.K. Dorhout, J. Appl. Phys., In Press, 2001 ⁶ Stress Version 1.0 Residual Stress Determination, Userâ€™s Manual (BrÃ¼ker AXS GmbH, Karlsruhe, Germany 1998).
FP-1-23 Blood Compatibility of Titanium Oxide Film Doped with Tantalum J.Y. Chen, N. Huang (Southwest Jiaotong University, China); P. Yang (City University of Hong Kong); Y.X. Leng, H. Sun, J Wang, G.J. Wan (Southwest Jiaotong University, China); Y. Leng (Hong Kong University of Science & Technology); P.K. Chu (City University of Hong Kong) Titanium oxide thin films have been investigated as biomedical materials, and their biocompatibility is key to their acceptance by the biomedical industry. Titanium dioxide films containing tantalum TiO2(Ta5+) are fabricated using plasma immersion ion implantation and deposition (PIIID) in this work. By changing the tantalum plasma density, we obtain a series of Ti-Ta-O films with different characteristics. To reveal the mechanism of blood compatiblility, the surface physical properties including surface energy parameters and semiconductor characteristics of the films are systematically investigated. The electrical resistivity, Hall mobility, Hall constant, and carrier concentration are measured. The surface energy parameters are obtained by measuring the contact angle between the liquid and film. To evaluate the relationship between the polar component as well as the dispersive component of the surface energy and the surface micro-structures, the surface morphology of the Ti-Ta-O films is characterized using an extended multimode nano-scope atomic force microscope (AFM). The blood compatibility of the films is evaluated in vitro by platelet adhesion investigation. The adhesion, activation, and morphology of the platelets are investigated employing scanning electron microscopy (SEM). The relationship between the surface physical properties and blood compatibility is studied to investigate the blood compatible mechanism.
FP-1-26 Correlation Between Residual Stresses and Adhesion of Plasma Sprayed Coatings: Effects of a Post-Annealing Treatment C. Godoy (Universidade Federal de Minas Gerais, BRAZIL); E.A. Souza (Petrobras, Brazil); M.M. Lima, J.C.A. Batista (Universidade Federal de Minas Gerais, Brazil) In thermal spraying processes, residual stresses mainly arise from two sources: (i) shrinkage of the spray particles after solidification and (ii) differences in the coating (α_r) and substrate (alphs_s) thermal expansion coefficients (secondary cooling process). In this present work, residuals stresses in plasma sprayed NiCrAl coatings, deposited at different thicknesses onto two steel substrates (AISI 1020 steel, α_r > α_s and AISI 304 stainless steel, alphs_r < alphs_s), have been theoretically predicted by mathematical expressions derived by Clyne and Gill, which only take into account the secondary cooling process. The residual stresses have also been experimentally determined by the curvature method and coating adhesion has been evaluated by tension tests. Experimental results revealed that the average residual stress in the coating and the average residual stress at the interface are both tensile when α_r > α_s and alphs_r < alphs_s. An agreement between the predicted and experimental residual stresses in the coating and at the interface was observed when α_r > α_s; however, when α_r < alphs_s such agreement was not found. Coating adhesion was found to decrease with increasing coating thickness, indicating a correlation between adhesion and average residual stresses at the interface instead of adhesion and average residual stresses in the coating. After annealing treatments for 10 hours up to 1073K, the average tensile residual stresses in the coating and at the interface increased for the NiCrAl/AISI 1020 steel composite system whilst a decrease was recorded for the NiCrAl/AISI 304 stainless steel system. Such opposite behaviours could be attributed to differences between the α_r and α_s values of both systems. These results indicate that post-annealing treatments in plasma sprayed coatings should be carried out taking into account the differences between the coating and substrate thermal expansion coefficients, especially to improve coating/substrate adhesion. In thermal spraying processes, residual stresses mainly arise from two sources: (i) shrinkage of the spray particles after solidification (secondary cooling process) and (ii) differences in the coating (α_x) and substrate (α_s) thermal expansion coefficients. In this present work, residuals stresses in plasma sprayed NiCrAl coatings, deposited at different thicknesses onto two steel substrates (AISI 1020 steel, α_x< α_s and AISI 304 stainless steel, α_x > α_s), have been theoretically predicted by mathematical expressions derived by Clyne and Gill, which only take into account the secondary cooling process. The residual stresses have also been experimentally determined by the curvature method and coating adhesion has been evaluated by tension tests. Experimental results revealed that the average residual stress in the coating and the average residual stress at the interface are both tensile when α_x < α_s and α_x > α_s. An agreement between the predicted and experimental residual stresses in the coating and at the interface was observed when α_x < α_s; however, when α_x > αsyb s such agreement was not found. Coating adhesion was found to decrease with increasing coating thickness, indicating a correlation between adhesion and average residual stresses at the interface instead of adhesion and average residual stresses in the coating. After annealing treatments for 10 hours up to 1073K, the average tensile residual stresses in the coating and at the interface increased for the NiCrAl/AISI 1020 steel composite system whilst a decrease was recorded for the NiCrAl/AISI 304 stainless steel system. Such opposite behaviours could be attributed to differences between the α_x and slpha_s values of both systems. These results indicate that post-annealing treatments in plasma sprayed coatings should be carried out taking into account differences between the coating and substrate thermal expansion coefficients, especially to improve coating/substrate adhesion.
FP-1-27 Microstructural Characterization of a NiWCrBSiC Alloy Coating Produced by HVOF Thermal Spraying L. Gil (Corrosion Studies Center, Venezuela); A. Quintero (Central University of Venezuela (UCV), Venezuela); D. Lewis (Sheffield Hallam University, United Kingdom); M.H. Staia (Central University of Venezuela (UCV), Venezuela) Nickel based self-fluxing alloys thermal sprayed have been used to protect machinery parts against wear and corrosion. Although the mechanical and chemical properties of nickel-base self-fluxing coatings are well known, the microstructural constitution of these coatings has not been fully analyzed. In this work, the influence of the processing parameters as spraying distance, the fuel/oxygen ratio (Fi) and the powder feed rate on the structure of a NiWCrBSiC alloy (Colmonoy 88) was extensively investigated. The coatings were thermal sprayed on a 1020 steel substrate using a JP-5000 gun. X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques were employed for the coatings microstructural characterization. The results indicated that the variation of the processing parameters in the range evaluated do no affect the nature of the phases corresponding to these coatings. It was determined that the as- sprayed coatings are formed by a multiphase structure with an inhomogeneous distribution of soluble elements in a gNi matrix. However, a well distributed network of hard phases in the matrix was found and these were identified as: Borides: W2B, B4Si, CrB41,W5(Si,B)3, Cr2Ni3B6, Cr5B3 ,Fe23B6, Fe4.5 Ni18.5B6 , B( Fe,Si)3, Cr1.8W3.2B3, Ni2B. Carbides: MC, M6C, M2C, M23C6 type carbides where Metals (M) are Chromium, Tungsten, Silicon and Nickel, complex carbides (W,Cr,Ni.Fe)xCy and borides (W,Cr,Ni.Fe)xBy. Carboborides: Fe23(C,B)6 and Silicides: Ni3Si, Ni2Si,(Cr,Si)3Ni2Si.
FP-1-28 Interfacial Indentation of NiCrAl Coatings Obrained by Thermal Spraying B. Pertuz (Laboratory of Mecahnics, LML URA CNRS 1441, France); J. Lesage, K. Chicot (Laboratory of Mechanics, LML URA CNRS 1441, France); L. Mraz, S. Smetana (Welding Institute, WUZ, Bratislava, Slovakia); M.H. Staia (Central University of Venezuela (UCV), Venezuela); G. Mesmacque (Laboratory of Mechanics, LML URA CNRS 1441, France) In order to appreciate the adhesion of thermal sprayed coatings, the laboratory of Lille has developed a methodology based on the interfacial Vickers indentation used to provoke the delamination of the coating, since the Vickers indentor acts as a wedge inserted between the coating and the subtrate. In association to the test, a mathematical approach allowing to define an "apparent interface toughness" assumed to represent the adhesion of the coating was also developed. This methodology has proved its usefulness in many different situations of coated materials and it was shown that the test applies successfully when the coatings have thickness more than 100 μm. However, the tests often failed when the coating was too thin or too brittle, since the Vickers indentation induced the fracture of the coating instead of the delamination at the interface. In these situations, it is expected that Knoop indentation at the interface (the larger diagonal at the interface) could replace the Vikers indentation, the former being less detrimental to the coating itself. NiCrAl coatings obtained by plasma spraying in air were tested and it was shown that the same experimental methodology can be applied to Knoop indentations results. Moreover, in these conditions it was shown that it is possible to apply higher loads and obtain better accuracy in the measurements. Finally, a very interesting result was observed since the same critical load value necessary to initiate a crack at the interface was obtained for the two indentor types.
FP-1-29 Kinetics of Plasma Electrolytic Oxidation of Ti-6Al-4V Alloy in Aluminate-based Electrolytes A.L. Yerokhin, A. Leyland, A. Matthews (University of Hull, United Kingdom) Plasma Electrolytic oxidation (PEO) of titanium aloys is of considerable scientific and industrial interest. Major principal characteristics of the process depend on the the oxide filmgrowth rate, which is affected not only by electrochemical reactions but also by plasma thermochemical effects. Whereas these reactions run on the surface concurrently, the net oxidation kinetics is not a simple function of the charge passing through the cell. Furthermore, the phase and structural state of the film evolves during its growth, making it difficult to predict the process parameters which ensure optimum combinations of kinetic and structural characteristics for these films. In this work, the kinetics of oxide film growth during PEO-treatment of Ti-6Al-4V alloy are studied. The process is carried out in solutions of sodium aluminate (0.05 - 0.2 mol/l) with some other proprietary stabilising ingredients for periods of time between 10 to 90 minutes at a current density of 5 to 30 A/dm². Methods of coulometric, gravimetric, SEM, EDAX and XRD analysis are employed to investigate the processes of mass transfer and phase-structure transformations in the surface layer developed. Effects of electrolyte composition, current density and processing time are discussed.
FP-1-30 Comparative Study of Interfacial Indentation of Cr_xC_yN_z-NiCr Plasma Spray Coatings Produced at Different Nitrogen Pressures M.H. Staia (Central University of Venezuela); T. Valente (Rome University "La Sapienza", Italy); A. Roman (Université de Franche-Comté, Montbéliard, France); J. Lesage, K. Chicot, G. Mesmacque (Laboratory of Mechanics, LML URA CNRS 1441, France) Plasma thermally sprayed Cr_xC_yM_z-NiCr coatings have been produced in different pressures conditions, ranging from 300mbars to 1200mbars, in nitrogen atmosphere by using a controlled atmosphere plasma spray system (CAPS). Vickers indentation test has been adopted as method to determine both the fracture toughness of these coatings and the interfacial adhesion. The fracture toughness was calculated by applying the traditional indentation toughness models found in the literature and the results were related to the sliding wear performance of these coatings. The interfacial toughness was calculated as function of the critical point (Pc and ac) and the aparent elastic modulus E. The critical point is the limit for which no crack is formed by indentation and is related to the coating adhesion to the substrate, as proposed by Lesage et al. Critical load values, Pc, varying between 2N to 40 N were obtained, which allow the ranking of these coatings function of their interfacial adhesion. The relationships between the results and the processing conditions were also explained.
FP-1-31 Thermal Stability of Cr Films on Sr TiO₃ (100) T. Wagner, Q. Fu (Max-Planck-Institut für Metallforschung, Germany) The thermal stability of ultra thin Cr overlayers on SrTiOsub 3@ (100) was investigated by in-situ reflection high-energy electron diffraction, X-ray photoelectron spectroscopy and scanning tunneling microscopy. The films were grown by molecular beam epitaxy at room temperature. Heating cycles showed that the interaction and solid state reaction between metallic Cr overlayers and SrTiO₃ can be divided into 3 steps: Annealing of the film below 640°C resulted in grain growth, transforming the initially polycrystalline films into epitaxial films with the following well defined orientation relationship: (100) SrTiO₃ \|\| (100) Cr, [001] SrTiO₃ \|\| [011] Cr. At temperatures above 650°C, oxygen bulk diffusion in SrTiO₃ was activated, accompanied by the transport of oxygen ions across the Cr/SrTiO₃ interface, resulting in the formation of an epitaxial chromium oxide phase. The oxidation process was accompanied by a morphological change of the overlayer. At temperatures beyond 750°C, interdiffusion of the Cr oxide film and SrTiO₃ substrate was observed.
FP-1-32 Photothermal Non-destructive Characterization of Zirconia Coatings F. Macedo, J.A. Ferreira, V. Teixeira (Universidade do Minho, Portugal); I. Valka (Technical University of Brno, Czech Republic) The evaluation of coating performances requires the development of reliable non-destructive evaluation (NDE) for quality control during and after manufacturing and for the in-service inspection. In this paper we report the NDE of layered systems by using photothermal techniques which allow the determination of coating thermal diffusivity and, by knowing the coating density, the thermal conductivity. A brief description of the photothermal technique developed at our laboratory which enables us to evaluate the thermal properties of several types of coatings and composite materials will be presented. Thermal waves, excited by intensity-modulated laser beam heating and detected by the photothermal beam deflection technique, were applied to thin stabilized Zr0₂-based coatings deposited on Ni-based superalloys. As this material is widely used as thermal barrier coatings, an accurate knowledge of their thermal properties is needed. These parameters are also of crucial importance because the right thermal and elastic parameters should be used in the modelling of thermo-mechanical behaviour of thermal barrier coatings at high temperature. Due to their relatively low values for the thermal properties, accurate values are difficult to measure by traditional techniques. In order to determine the thermal diffusivity of the Zr0₂2 coatings a multiparameter fitting was applied to the experimental data. The results obtained quite well agree with some previously reported by other authors for similar coatings.
FP-1-33 Tunneling Acoustic Sensor for Non-contact Nondestructive Testing of Thin Films V.J. Valuisky (UDACHA-Diamond, Ukraine); O.G. Lysenko, V.I. Grushko (Institute for Superhard Materials, Ukraine) The acoustic method is widely used in nondestructive testing. When acoustic signals are used to study thin films, all contacting transducers physically coupled with the material surface may add mechanical loading, which can be an additional source of signal distortion. Laser methods for acoustic measurements are rather difficult. We developed a new technique to measure surface acoustic waves using phenomena of tunneling current. The strong exponential dependence of the tunneling current on the tip-to-sample spacing makes it possible to use this current in measurements of surface acoustic waves. A theoretical model that captures the most significant features of wave phenomena in thin films is described. Laboratory experiments are shown to yield results that are in excellent agreement with those obtained from theoretical model.
FP-1-35 Improving the Load Carrying Capacity of a Layered System Due to the Design of a Film Stack with an Optimized Modulus Variation I. Hermann, T. Chudoba, V. Linss, N. Schwarzer, F. Richter (TU Chemnitz, Germany) The present investigation has been conducted in order to verify a recently proposed coating design ¹ for the improvement of the load carrying capacity that is based on a certain variation of the Young's modulus with depth. For this reason B-C-N films were deposited on fused silica and Si by reactive magnetron sputtering ². The Young's modulus of the films could be varied between 100 GPa and 300 GPa simply by changing the Ar/N₂ ratio in the working gas. In a first step Young's modulus and yield strength of single layers on fused silica and Si were measured by nanoindentation experiments using different spherical indenters between 1 and 11 micrometer radius. The analysis of the load-displacement data and the optimization were carried out using the ELASTICA software ³. It allows a fast analytical calculation of the complete stress and deformation field within coated systems under Hertzian contact. The known dependence between N₂ content in the working gas and the mechanical properties of the films was used for the design of an optimized three-layer system on fused silica. Film thickness and modulus were calculated in such a way that the von Mises stress and the tensile stress maxima in the vicinity of interfaces could be markedly reduced for the loading conditions during the contact with a spherical indenter. In this way the critical load for the onset of plastic deformation was considerably rised, compared to a one layer system. . ¹ N. Schwarzer, Surf. Coat. Technol. 133 -134 (2000) 397 - 402. ² V. Linss et al., this conference. ³ T. Chudoba, N. Schwarzer, ELASTICA, software demonstration package, available in the Internet at: http/www.tu-chemnitz.de/~thc/ .
FP-1-36 An Experimental Study of the Influence of Imperfections on the Buckling of Compressed Thin Films M.-W. Moon (Princeton Materials Institute and Seoul National University, Korea); J.-W. Chung, K.-R. Lee (Korea Institute of Science and Technology, Korea); K.H. Oh (Seoul National University, Korea); R. Wang (University of British Columbia); A.G. Evans (Princeton University) The role of imperfections on the initiation and propagation of buckle driven delaminations in compressed thin films is demonstrated using experiments performed with diamond-like carbon (DLC) films deposited onto glass substrates. The surface topologies and interface separations are characterized by using the Atomic Force Microscope (AFM) and the Focused Ion Beam (FIB) imaging system. The wavelengths and amplitudes of numerous imperfections are measured by AFM and the interface separations characterized on cross sections made with the FIB. Chemical analysis of several sites, performed using Auger Electron Spectroscopy (AES), has revealed the origin of the imperfections. The incidence of buckles is correlated with the imperfection wavelength. The findings are rationalized in terms of theoretical results for the effect of imperfections on the energy release rate.
FP-1-37 Correlation Between Growth Mode and Mechanical Properties of BCN Coatings Deposited by PECVD R. Cremer (RWTH Aachen LTH, Germany); D. Dietrich (Chemnitz University of Technology, Germany); K.-U. Körner (Professur Physikalische Chemie, TU Chemnitz, Germany); D. Kurapov (LTH, RWTH Aachen, Germany); S. Schulze (Professur Analytik der Festkörperoberflächen, TU Chemnitz, Germany); T. Thamm (Chemnitz University of Technology, Germany); D. Neuschütz (LTH, RWTH Aachen, Germany); G. Marx (Chemnitz University of Technology, Germany) BCN films were deposited by plasma enhanced chemical vapor deposition (PECVD) from a variety of metall-organic and cloridic precursors. The films were analyzed with respect to composition, morphology and microstructure by X-ray spectroscopy (WDX), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron spectroscopy (TEM) and energy loss spectroscopy (PEELS). Depending on the process parameters amorphous BCN, turbostratic BCN, and nanocrystalline h-BCN, occasionally with a c-axis orientation parallel to the surface or amorphous were deposited. High resolution images confirmed the different orientation preferences of the atomic lamellae detected by XRD. Special attention was paid to the correlation of these observations with the mechanical properties of the films as characterized using both, the traditional Vickers method and the determination of the hardness under load. The results illustrate, that the hardness as well as the elasticity of BCN-coatings are strongly influenced by the crystallographic structure of the coatings.
FP-1-38 Residual Stress Measurements on Electrodeposited CdIn₂Te₄ Films S. Kohli (Colorado State University); R.K. Sharma, A.C. Rastogi (National Physical Laboratory, India); C.D. Rithner, P.K. Dorhout (Colorado State University) CdTe and its alloys are important materials for their application in photovoltaic devices and as a substrate material for IR detectors. Its crystal structure, electronic, vibrational and high pressure properties have been investigated. However, to the best of knowledge there are no reports for the analysis of residual stress in these films and their effect on the structure, optical and electrical properties of these materials. In the present paper we will report the x-ray residual stress measurements on the electrodeposited CdIn₂Te₄ films with varying thickness. Data for x-ray photoelectron spectroscopy (XPS), specular x-ray reflectivity (XRR), glancing angle XRD (GAXRD) measurements, optical absorption spectroscopy in the wavelength range 250-1200 nm will also be presented. The residual stress measurements will be performed using conventional Sin²ψ method and complete stress tensor will be evaluated.
FP-1-39 Electroless Copper Plating for ULSI Interconnects Through the Pd/Cu-Catalytic Effects by PIII J.H. Lin, W.J. Hsieh, X. W. Liu, Yi-Ying Tsai, H.C. Shih (National Tsing Hua University, Taiwan, ROC) The major goal of this study is to combine the techniques of using plasma immersion ion implantation (PIII) to implant Pd or Cu as a catalyst seed layer onto an a-Ta:N diffusion barrier layer and electroless plated Cu to accomplish the ULSI interconnection metallization. Both patterned and blanked wafers were employed using Pd or Cu as catalyst by PIII after which copper was electroless plated on an a-Ta:N/FSG/Si multi-layer structure. Either Pd or Cu atoms were sputtered from a negatively biased target and ionized in an argon inductively coupled plasma (ICP). The metal ions were adequately implanted into the substrate with a highly pulsed negative bias (~4000 V). The observation of FESEM indicated that under the circumstances of higher substrate bias voltage and plasma ionization, the electroless copper grows upward from the bottom of the vias (width: 0.25 µm; aspect ratio: 7) layer by layer, with an excellent gap filling ability without the final centered seam. The result of the pull-up test, showed that higher substrate bias and higher plasma density to implant Cu as seed layer can effectively enhance the adhesion strength between electroless-plated copper film and a-Ta:N layer.
FP-1-40 Structural and Electrical Characteristics of Epitaxial CoSi₂ Formed on n-Si0.83Ge0.17/n-Si(001) Using Si capping layer by MOCVD Session : F5.Characterization of Thin Film Growth Mechanism and Evolving Film Properties D.O. Shin (Sungkyunkwan University, Korea); N.-E. Lee (CAPST, Korea) CoSi₂ formation on SiGe alloys has been studied for low-resistance contacts and Schottky barrier contacts for various applications. Among the various silicides, CoSi₂ is a very attractive material due to its low resistivity and possibility of self-aligned silicide formation at relatively low temperatures. Recently, there have been several investigations on epitaxial CoSi₂ deposited by molecular beam epitaxy on SiGe alloys or by silicidation of sputter-deposited Co layers on Si/SiGe alloys, but no reports on epitaxial CoSi₂ deposited by CVD on SiGe using a sacrificial Si so far as we know. In this study, we investigated structural and electrical properties of epitaxial CVD-CoSi₂ /n-Si_0.83Ge_0.17/n-Si(001) contacts by structural, chemical, and electrical analyses. Uniform cobalt disilicide (CoSi₂) layers has been grown in-situ at 100 mTorr on Si(capping layer)/n-type Si_0.83Ge_0.17 grown on n-type Si(001) by metal organic chemical vapor deposition (MOCVD) at 600°C using cyclopentadienyl cobalt, Co(η⁵-C₅H₅)(CO)₂ with 10 sccm of H₂ carrier gas. The interfacial, structural, and chemical properties of epitaxial CoSi₂/n-Si_0.83Ge_0.17 were analyzed by x-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Rutherford backscattering spectroscopy (RBS), and Auger electron spectroscopy (AES). The effective Schottky barrier heights (Φ_B) and electrical properties of CVD-CoSi₂/Si_0.83Ge_0.17/Si(001) were measured by current-voltage (I-V) measurement and the sheet resistance measurement, respectively.
FP-1-41 Evaluation of Diffusion Barrier Capability for Ta-N System in Copper Interconnection K.L. Lin, J.G. Duh (National Tsing Hua University, Taiwan, ROC) Ta-N thin films were deposited on the n type Si(100) substrate by reactive sputtering for potential application of the diffusion barrier layers in Ultra-large-scale integration (ULSI). Barrier films performance is affected by various deposited parameters in the sputtering system, including flow rate of reactive gas, working distance and RF power density. The electrical resistivity of the tantalum nitride films increases with incorporated nitrogen atoms and gradually rises to around 500µΩ-cm as the nitrogen in the film increases to 50%. When the concentration of nitrogen is beyond 50 at.%, the resistivity rises rather sharply. Assemblies of Cu/Ta/Si, Cu/Ta₂N/Si, Cu/Ta₂N/SiO₂, Cu/TaN/Si and Cu/TaN/SiO₂ were annealed in the temperature range 500-800°C. Several characterization methods were employed to evaluate the capability Ta-N related systems of the diffusion barrier material than others to resist the diffusion of copper.
FP-1-42 Annealing Effects of the IMP Deposited Copper Films on the Ti-based/Ta-based Diffusion Barrier Layer T-L. Lee (National Chiao-Tung University, Taiwan, ROC); J.H. Lin, H.C. Shih (National Tsing Hua University, Taiwan, ROC); C-L. Lin (National Chiao-Tung University, Taiwan, ROC) The study concentrates on the Cu/diffusion barrier interfacial mechanism of the IMP Ti, TiN, Ta, TaN and TaSiN thin films in the Cu/barrier/FSG system. The copper films were deposited by IMP with 1.5 µm thick on different barrier layer. The copper plated specimens were annealed from 150 to 800°C in the 10 % H₂ + 90 % N₂ mixed gas for the annealing effects study. The properties of IMP copper films have been investigated as a function of annealing temperatures together with the diffusion barrier performance. The XRD spectra showed that the as-deposited copper films on all barrier layers have obvious Cu (111) preferred orientation, especially for TaN. The crystal graphic was characterized by FESEM/EBSD and XRD. Copper films deposited on Ti and Ta, the Cu (111) texture were strengthen by the 150 to 500°C annealing. AES/XPS, HRTEM, and RBS results showed that TaN and TaSiN as the diffusion barrier between copper and FSG up to 800°C; however, IMP Ta, Ti and TiN barrier failed at lower annealing temperatures.
FP-1-44 Optimizing the Corrosion Resistance of HVOF Ni- based Coatings by Using Experimental Design L. Gil (Corrosion Studies Center, Venezuela); M.H. Staia (Central University of Venezuela (UCV), Venezuela) Experimental design is an effective method for conducting a reduced number of experiments in order to obtain the optimum spraying conditions and enhance the thermal sprayed coatings properties. In the present study, a 33 factorial design experiment was used to establish the effects of the variables on the coatings quality in relation to the corrosion behavior of an HVOF thermally sprayed Ni based self-fluxing alloys in a 3.5 % NaCl solution. Response surface methodology (RS) was employed to describe empirical relationships among variables as the spraying distance, the fuel/ oxygen ratio and the powder feed rate. The maps obtained allowed the selection of the optimum operating conditions to achieve the desired specifications of the HVOF coatings for their best corrosion resistance in the chosen environment. The analysis of the results indicates that the spray distance and fuel/ oxygen ratio have a significant effect on the porosity, microstructure and corrosion resistance, and that these properties are virtually invariant with the powder feed rate. The structure and mechanical properties of the as-deposited coatings together with the microstructural characterization of the corrosion products of the best coatings produced, as result of the factorial design experiment, are also addressed.
FP-1-45 The Degradation of CrN Films at High Temperature Under Controlled Atmosphere F.-H. Lu, C.-H. Hung (National Chung Hsing University, Taiwan, ROC) The degradation of CrN films prepared by cathodic arc plasma deposition onto Si substrates was investigated in the temperature range of 300-1200^oC under different atmosphere. The gases with drastically different nitrogen and oxygen partial pressure ratios used in annealing include air, N₂, Ar, and Ar/N₂/H₂ mixtures. The degradation contains both color changes associated with the phase transformation of CrN into Cr₂N as well as oxidation and crack formation of the films. The phase transformation of CrN into Cr₂N occurring in the low temperature range starting at 500^oC is mainly due to stress relaxation while taking place at high temperatures can be explained by thermodynamics. The oxidation induced phase change characterized by XRD and XPS has been analyzed by evaluating the Gibbs free energy change in the oxidation. The thermally induced cracks of the films have also been analyzed.
FP-1-46 Formation of SiO₂ Aerogel Films on S-passivated GaAs Surface Using (NH₄)S₂ and S₂Cl₂ Solutions S-W. Park, S-B. Jung (Yonsei University, Korea); H-H. Park (Yonsei Univeristy, Korea); H-C. Kim (Electronics and Telecommunications Research Institute, Korea) Formation of SiO₂ aerogel films on S-passivated GaAs surface using (NH₄)₂S and S₂Cl₂ solutions For the introduction of low-k material to GaAs based device is inevitable for the realization of high speed and high density devices. However it is well known that surface/interface state of GaAs is very important because the electrical properties and reliability of GaAs based devices greatly depends on it. In our preliminary study for applying SiO₂ aerogel on GaAs as an interlayer dielectric, the surface degradation of S-passivated GaAs was observed due to the weak bonding nature of As-S passivation bonding layer. In this work, several kinds of pre-cleaning and S-passivation solutions were compared to form an effective S-passivation layer, protecting GaAs surface during the formation of SiO₂ aerogel. For this, especially S₂Cl₂ solution was adapted and compared with (NH₄)₂S solution. Scanning electron microscopy, Auger electron spectroscopy, and X-ray photoelectron spectroscopy are used to investigate the resistance of S-passivated GaAs during the formation of SiO₂ aerogel film. Electrical properties of SiO₂ aerogel/S-passivated GaAs were also examined to establish the relationship between the interfacial state and the properties.
FP-1-47 Substrate Heating Effects in CdS Thin Films Grown by Chemical Bath Deposition. O Calzadilla (Facultad de Fisica, Universidad de La Habana, Cuba, Mexico); F. Caballero-Briones, M. Zapata-Torres, J.L. Peña-Chapa, A. Zapata-Navarro (CICATA-IPN Unidad Altamira, Mexico) Cadmium sulphide (CdS) is a II-VI semiconductor material with appropriate properties for the fabrication of optoelectronic devices. Among various techniques used for the preparation of CdS films, Chemical Bath Deposition (CBD) is a simple and inexpensive method. This growth method yields stable, adherent and hard CdS films with good reproducibility. However, it has been found that depending of the growth kinetics, the crystalline structure of the chemically deposited CdS films can be hexagonal (wurzite), cubic (zincblende) or a mixture of them. Many factor like as the temperature of the solution, concentration of metal ions in the bath between other, are related with the quality of the films. On the other hand, the grow rate is controllable by pH, temperature of solution and relative concentration of reactants in the bath solution. External factors such as magnetic field application, illumination of the substrate during the growing time, seeding of the substrate in the initial time before the film deposition have been studied. In this paper is studied the effect of using an external heater for the substrate and a relatively low temperature in the solution on the properties of CdS films prepared by the CBD technique. A study of the film structure by x-ray diffraction has been done. The immediately effects are better crystalline quality and higher thickness of the films.
FP-1-48 MEVVA Ion-Implanted Cr Interlayer on the Microstructure of CrN on Steel S. Han (National Taichung Institute Technology, Taiwan, R.O.C.); X.J. Guo (National Tsing Hua University, Taiwan, R.O.C.); K.W. Weng (National Chung Hsing University, Taiwan, R.O.C.); J.H. Lin (National Tsing Hua University, Taiwan, R.O.C.); D.Y. Wang (National Chung Hsing University, Taiwan, R.O.C.); H.C. Shih (National Tsing Hua University, Taiwan, R.O.C.) The effect of MEVVA ion-implantation of Cr on the microstructure and properties of CrN coatings on the steel were investigated in this paper. Two types of CrN-coated specimens (CrN/steel and CrN/Cr/steel) by cathodic arc plasmas deposition were prepared with and without an interlayer deposited by MEVVA ion-implantation of Cr. And the microstructure and microchemistry of chromium nitride has been investigated by using X-ray diffraction (XRD), cross-sectional transmission electron microscopy (XTEM) and selected area diffraction (SAD). Therefore, the coatings exhibit a microcolumnar morphology. The outermost layer of the coating is identifed as CrN. Furthermore, from an estimation of the unrelaxed thermal stresses based on a bilayer model, it is demonstrated that the presence of a Cr interlayer between CrN and steel can dramatically reduced the thermal stress in the CrN coatings.
FP-1-50 Determination of an Electron Temperature Profile Above the Evaporative Source in Ion Plating Discharges by Spatially Resolved Optical Emission Spectroscopy. A.D. Wilson, A. Davison, A. Leyland, A. Matthews, K.S. Fancey (University of Hull, United Kingdom) Electrostatic (Langmuir) probes have been used extensively to investigate plasma parameters such as the electron temperature, Te, but probe contamination and localised distortion of the plasma by the probe are well-documented problems. Previous studies by the authors [1,2] have estimated Te for argon-based diode, triode and ion plating discharges using Optical Emission Spectroscopy (OES) as a non-intrusive diagnostic technique. Te was determined by the use of selected argon atom and ion spectral line intensities, based on theory that assumes parameters relating to equilibrium plasma conditions. Although the technique could only be expected to provide an approximate analysis under "real" discharge conditions, a slight increase in Te was found with hot filament (tungsten) thermionic electron emission enhancement of the discharge. More importantly, the analysis indicated a significant increase in Te during metal evaporation, the effect apparently decreasing with increasing chamber (argon) pressure. Gas rarefaction above the melt and Penning ionisation of the metal by argon metastables are possible explanations for the observed effects. This paper reports on further work to investigate these phenomena using spatially resolved OES at various distances from an evaporative source, both before and during evaporation. [1] K S Fancey and A Matthews, Vacuum, 42 (15), (1991), 1013-1015 [2] A D Wilson, A Davison, A Leyland, A Matthews and K S Fancey, Ion Plating Discharges: Further evidence of metal cluster formation and an increase in electron temperature during metal evaporation, submitted to Appl Phys Lett.
FP-1-51 Influence of Composition and Structure on the Mechanical Properties of BCN Coatings Deposited by Thermal CVD S. Stöckel, K. Weise, D. Dietrich, T. Thamm, M. Braun, G. Marx (Chemnitz University of Technology, Germany); R. Cremer, D. Neuschütz (RWTH Aachen, Germany) BCN films were deposited by isothermal chemical vapor deposition (CVD) from gaseous mixtures of trimethylborazine, toluene, nitrogen and ammonia. The films were analyzed with respect to chemical state, composition, morphology and microstructure on the one side oxidation behavior and hardness on the other side. X-ray spectroscopy (WDX), photoelectron spectroscopy (XPS), Raman and infrared spectroscopy (IR), differential thermal analysis (DTA), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron spectroscopy (TEM) and electron energy loss spectroscopy (EELS) were employed for film characterization. Depending on the carbon content hard BCN coatings were obtained. Their hardness, which was determined under load, rapidly increased for carbon contents above 50 at.%. All measurements indicate that in these coatings t-BN or h-BN, respectively, and graphite like carbon exist side by side.
FP-1-52 Development of Surface Coating Technology of TiO₂ Powder and Improvement of Photocatalytic Activity by Surface Modification TaeKwan Kim, M.N. Lee (Environmental Research Laboratory, Korea); S.H. Lee, Y.C. Park, J.-H. Boo (Sung Kyun Kwan University, Korea) Titanium dioxide (TiO₂) has been known as a useful photocatalytic material because it is photosensitive, stable, and inexpensive. In this study, we synthesized the TiO₂-based photocatalysts and developed a surface modification technology for improving their photocatalytic activity for total destruction of organic compounds in polluted air and wastewater. Electronic modification of the photocatalysts by PACVD coating of metal oxides such as Fe₂O₃ and Al₂O₃ has a strong effect on the photoreactivity of the TiO₂-based photocatalysts. The efficiency of electron-hole separation and the dynamics of interfacial electron transfer can be dramatically influenced. The structural and compositional changes as well as optical characteristics are mainly investigated by X-ray diffractometry (XRD), X-ray photoelctron spectroscopy (XPS), UV-Visible spectrometry, and photoluminescence (PL) measurements. In addition, electron spin resonance (ESR) studies have also been carried out to verify the existence of paramagnetic species such as OH and H₂O radicals on UV-irradiated TiO₂-based photocatalysts. ESR data showed that the hydroxy radicals can decompose organic pollutants into harmless products since they have high oxidizing powder. From the reduction test of nitrobenzene, for example, it is found that the photocatalytic effect of TiO₂-based photocatalysts coated with metal oxides are was twice better than that of commercially available non-coated TiO₂ photocatalysts. In the case of photocatalytic oxidation reaction of phenol, moreover, experimental results on decomposition of phenols under UV irradiation with these TiO₂-based photocatalysts showed a consistency with ESR data indicating that TiO₂ coated with metal oxides will be one of the most effective photocatalysts.

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