F Poster

Wednesday, April 12, 2000 5:00 PM in Room Atlas Foyer

FP-1 A Quantum-Mechanical Model to Understand the Promotion of Tetrahedral Bonds by Carbon Subplantation in Diamond-Like Carbon Films
H.J. Steffen (Mannheim University of Applied Sciences, Germany)
A simple self-consistent electronic structure calculation within the density-functional scheme reveals the electron-density dependent hybridization state for a carbon atom embedded in a homogeneous electron gas. It is shown that the p-like character of this quasiatom exceeds the s-like state and a hybridization is naturally induced in an environment of high atomic density. Consequently, the mechanism for the formation of tetrahedrally coordinated carbon atoms in diamond-like films can be attributed to the rise of the average electron density owing to the enforced carbon subplantation and increased film density. The derived mechanism for promoting hybrid bonds is in accordance with experimental results which show a dose- dependent variation of the bond fractions within an evolving amorphous network during low-energy carbon ion deposition.
FP-2 Properties of Non-Stoichiometric Titanium Oxide Biomaterials Synthesized by PIII
Y.X Leng, P.K. Chu, B.Y. Tang (City University of Hong Kong); J.Y. Chen, P. Yang, Z.R. Zhou, N. Huang (Southwest Jiaotong University, China)
Ion implantation offers a large number of actual and potential applications in widely varying fields of modern biomedical technology, especially with regard to artificial internal organ research. However, conventional ion beam processes such as ion beam assisted deposition (IBAD) are “line-of-sight” techniques only suitable for flat substrates. Plasma immersion ion implantation (PIII) circumvents the line-of-sight restriction, and large, complex-shaped medical devices can be implanted. Non-stoichiometric titanium oxide (TiO@sub 2-x@) films are potentially useful as blood contacting materials such as heart valves and struts inside blood vessels, but the properties of TiO@sub 2-x@ films prepared by PIII have seldom been shown. In this work, TiO@sub 2-x@ films are synthesized on titanium substrates by PIII utilizing titanium metal plasma and reactive plasma oxidation. By controlling the deposition rate of titanium and the density of the oxygen plasma, TiO@sub 2-x@ films with different Ti to O ratios can be fabricated. The chemical composition of the titanium oxide films is measured by Auger electron spectroscopy (AES), and the valence state of the elements is determined by x-ray photoelectron spectroscopy (XPS). X-ray glancing diffraction is employed to identify the structure of the films. The mechanical properties of the films are assessed by micro-hardness and pin-on-disk wear tests. The results show that the hardness of TiO@sub 2-x@ films reaches 1000kg/mm@super 2@” or above. The wear resistance of the TiO@sub 2-x@ films is similar to that of titanium nitride films. The relationship between composition, structure, and surface mechanical properties is investigated systematically.
FP-3 The Effect of Cr Interlayer on the Microstructure of CrN Coatings on Steel
S. Han (National Chung Hsing University, Taiwan,ROC); J.H. Lin, X.J. Guo, S.H. Tsai (National Tsing Hua University, Taiwan,ROC); F.H. Lu (National Chung Hsing University, Taiwan,ROC); H.C. Shih (National Tsing Hua University, Taiwan,ROC)
The effect of electroplated Cr on the microstructure and properties of CrN coatings on the steel was investigated. Two types of CrN-coated specimens by cathodic arc plasmas were prepared with and without an interlayer deposited by electroplated hard chrome. The microstructure and microchemistry of chromium nitride has been investigated using XRD,SEM, XTEM and SAD. The coatings are fairly dense with a microcolumnar morphology. The lattice fringes are continuous across the boundaries between the central thin layer of Cr and the surrounding darkish layers of CrN. The outermost layer of the coating is identifed as CrN. The residual stresses in CrN caused the formation of dislocation networks and cell walls in the steel. 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 coating.
FP-4 The Effect of Intrinsic Parameters on the Critical Load as Measured with the Scratch Test Method
N.X. Randall (CSEM Instruments, Switzerland); C. Frankel (Penn State University)
In the scratch test method, scratches are generated on the coated sample using a diamond indenter (usually a Rockwell C profile) which is drawn across the surface under either constant or progressively increasing load. The sample is displaced at constant speed and at a certain load damage occurs along the scratch path. This value of critical load, Lc, can be used to accurately characterise the adhesive strength of the coating-substrate system. With modern scratch testing instruments, the critical load can be determined by acoustic emission, optical microscopy, variation in penetration depth or variation in the tangential frictional force between tip and sample. However, it is difficult to express the adherence of a coating-substrate system in a quantitative way because the critical load depends on several parameters related to the testing conditions.@paragraph@Experience in the scratch testing field has shown that various different radii of diamond indenter are often required in order to adequately characterise the adhesion of modern thin films and coatings. The constant reduction in thickness of coatings, as well as the increase in development of softer (polymeric) coatings has meant that a whole range of indenter geometries are needed to cover the scope of elastic and plastic properties measured by scratch testing. This paper considers the effect of intrinsic parameters such as scratching speed, loading rate and diamond indenter radius on the measured critical load for scratch tests performed on various different coating-substrate combinations (TiN, W, DLC, Al and Au). Results are presented which suggest definite correlations between critical load and indenter radius, and which should aid users in making the right choice of indenter for a given coating-substrate system.
FP-5 X-Ray Fluorescence Characterization of Films at the Grazing Reflection of X-Ray Beam Formed by the Slitless Collimation.
V.K. Egorov (Ipmt Ras, Russia)
The model of X-Ray fluorescence analysis at the total reflection of the excitating X-Ray beam (TXRF) is a fairly established technique for the quantity chemical diagnostic of surface layers with 2-5 nm thickness of polished targets today. There are the beautiful industrial TXRF spectrometers (for example, EXTRA II - Sèifert, RUGAKU-3700) but cost of it's equipment is very high. The present work describes of TXRF spectrometer modified by using of the slitless collimator for the primary X-Ray beam. The prime cost of our spectrometer is not over 20000$ at the excellent analytical characteristics and a simplicity of the using.@paragraph@ Standard TXRF spectrometer is complete by the monochromator for the forming of the excitating X-Ray beam with angle divergence near 0.001@super o@. The primary X-Ray beam in our spectrometer is formed by the slitless collimator X-Ray radiation comprising two quartz polished plates intimate mated together. In a clearance between this plates the standing wave arises transported the beam on the distance near 100 mm without weakening. The beam divergence in output of the collimator is equal to double value of the total reflection critical angle for a quartz (2@THETA@@sub c@~0.2@super o@). Half of this beam is a source of X-Ray fluorescence excitation in the target studied. The X-Ray density on the surface layer of a target in our spectrometer is higher two orders in compared with a standard one.@paragraph@ It guarantees the reduction of the contamination detection levels for the TXRF spectrometer with slitless collimator no less then the order. The detection limits for the Fe group elements at the surface analysis of Si wafer are obtained better then 10@super 10@ atoms/cm@super 2@ in measurements with the standard X-Ray tube (Mo, 2 kW) at the exposition time 600 sec.
FP-6 Numerical Interpretation of Reflectance/Transmittance Difference Spectroscopy of an-isotropic Multi-layer Thin Film
D.T. Kwok, P.K. Chu (City University of Hong Kong)
Reflectance/Transmittance-difference (anisotropic) spectroscopy (RDS/TDS) is one of the few non-destructive optical techniques that one can use to study surface thin films and the interface of semiconductor materials under steady-state conditions. RDS spectra have been successfully acquired from various kinds of semiconductor layered structure, such as ZnSe/GaAs interfaces, (001) GaAs, etc. However, the spectra are hard to interpret when more than one layer is anisotropic. In this paper, a numerical method based on the 2x2 matrices established by Yeh is applied to simulate the non-normal-incident RDS and TDS spectra of biaxial anisotropic multi-layer systems with finite thickness. It is demonstrated that, when the principal axes of the anisotropy layer are at certain orientations, a RDS/TDS spectrum can be separated into two spectra, namely, an in-plane anisotropic spectrum and an out-of-plane anisotropic spectrum. It is shown that the separation is valid for large in-plane an-isotropy and an incident angle of less than or equal to 20 degrees.
FP-7 Mechanical Properties of Ion-Plated TiN Films on 304 Stainless Steel
J.H. Huang, G.P. Yu, W.C. Chou (National Tsing Hua University, Republic of China)
Titanium nitride (TiN) film was deposited on 304 stainless steel using a hollow cathode discharge ion-plating (HCD-IP) technique. Film thickness was successfully controlled in the HCD-IP processing, and the composition of the films was kept constant under the same deposition condition with various film thickness. The effect of film thickness on the structure and mechanical properties of TiN film was investigated. X-ray diffraction (XRD) was used to determine the preferred orientation of TiN film and the residual stress in the TiN film. In the aspect of mechanical properties, hardness was measured by an ultra-microhardness tester and the ultimate interfacial shear stress was determined by in-situ strip tension of the TiN-coated specimens in a scanning electron microscope (SEM). The composition depth profiles of TiN films were obtained using a secondary ion mass spectrometer (SIMS). The N/Ti ratios were measured by both X-ray photoelectron spectrometer (XPS) and Rutherford backscattering spectrometer (RBS). The packing factors of TiN films can also be obtained from the results of RBS. The results showed that (111) is the dominant preferred orientation of the TiN coatings in most of the deposition conditions, especially as film thickness greater than 1 micrometer. The hardness values of TiN film were about 23 ~ 24 GPa as the film thickness close to 1 micrometer. The limiting thickness for the measurement of interfacial shear strength by the in-situ strip tension method is about 0.5 micrometer. The packing factor has a linear relationship with thickness and levels off when thickness larger than 1.2 micrometer. Comparing the N/Ti ratios measured by RBS with those by XPS, the results were slightly lower for XPS, which may be due to the preferential sputtering of N during pre-sputtering before XPS measurement.
FP-8 Investigations on the Energy Influx at Plasma Processes by Means of a Simple Thermal Probe
H. Kersten, H. Deutsch, R. Hippler (University of Greifswald, Germany)
In technological applications as etching or deposition of thin films, the energy balance of the substrate is affected by the plasma itself. Hence, the experimental determination of the energy influx towards the substrate is of great importance.@paragraph@ The total energy flux has been measured by means of a simple thermal probe. The procedure is based on the measurement of temporal slope of the substrate temperature during the plasma process. A substrate dummy of known heat capacity, which is thermally isolated is inserted into plasma at substrate position. The obtained heating curve and (after switching-off the plasma) the cooling curve are taken and their time derivatives at the same environmental temperature are calculated. By knowing the heat capacity of the sensor, the difference of the derivatives is a measure of the deposited power at the surface. By means of the dummy it is also possible to measure the substrate current simultaneously. In order to vary the contribution of the charge carriers to the energy influx, an additional substrate bias voltage can be realized, too. The presented thermal probe allows for sensitivities of about 10@super -3@ J/cm @super 2@s and it can be simply used under typical plasma environments.@paragraph@ The procedure has been demonstrated for different applications were the probe has already been employed. Examples are a-C:H film deposition in a CH@sub 4@-ECR plasma and by magnetron sputtering of a graphite target in Ar/H@sub 2@, respectively, and the energy flux measurement in an RF plasma which is used for the modification of micro-disperse powder particles.
FP-9 Exploring the Metallic Seeding by PIII for the Growth of Electroless Plated Cu on the TaN-Insulated SiO@sub 2@ Film
J.H. Lin (National Tsing Hua University, Taiwan, ROC); Y.Y. Tsai (National Tsing Hua University, Taiwan, ROC); S.Y. Chiu (National Chiao Tung University, Taiwan, ROC); J.M. Tsai, C.S. Kou (National Tsing Hua University, Taiwan, ROC); M.S. Feng (National Chiao Tung University, Taiwan, R.O.C.); H.C. Shih (National Tsing Hua University, Taiwan,ROC)
Selective copper plating was carried out using Pd and Cu as metallic catalysts by plasma immersion ion implantation (PIII) on which Cu was electroless plated. The metal was 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 (~ 6 kV). The substrate has a layer of previously coated TaN on SiO2 as a diffusion barrier by the sputtering deposition before PIII (~ 500Å). The implantation doses of the specimens were analyzed by SIMS and RBS measurements. The crystallographic texture of the electroless plated copper on the sample was analyzed by X-ray diffraction pole figure. TEM, AFM and SEM were used to elucidate the growth mechanism of the copper film on Pd-seeded layer and on Cu-seeded layer by PIII. A high deposition rate and improved adhesion strength were achieved when copper film on the PIII seeded specimens was deposited by electroless plating.
FP-10 Structural Characterization of Epitaxial Bi@sub 2@Sr@sub 2@CuO@sub 6+x@ Thin Films Deposited on SrTiO@sub 3@ Substrates Using Inverted Cylindrical Magnetron Sputtering
M. Ye, Y.Z. Zhang, M.P. Delplancke-Ogletree, R. Deltour (Université Libre de Bruxelles, Belgium)
High quality epitaxial Bi@sub 2@Sr@sub 2@CuO@sub 6+x@ thin films were deposited on (100) SrTiO@sub 3@ substrates using inverted cylindrical magnetron sputtering method. Their structural properties, regarding to the orientation, surface morphology, composition, surface and interface microstructure, were studied by x-ray diffraction, scanning electron microscopy, atomic force microscopy, Auger electron spectroscopy, and transmission electron microscopy. The influence of the deposition parameters on the superconducting and structural properties of these epitaxial Bi@sub 2@Sr@sub 2@CuO@sub 6+x@ thin films will be reported.
FP-11 Nanotribology and Surface Chemistry of Reactively Sputtered Ti-B-N Hard Coatings
R.D. Ott, C. Ruby, F. Huang, M.L. Weaver, J.A. Barnard (University of Alabama)
This study evaluates the nanotribological performance of thin, hard protective coatings of Ti-B-N deposited by a dc magnetron sputtering process. Films, 500 nm in thickness, were deposited on silicon wafers from a TiB@sub 2@ target in varying Ar plus N@sub 2@ atmospheres, with the atomic percent of nitrogen ranging from 0 to 38%. A correlation is established amongst the chemical state, structure, mechanical properties, and nanowear resistance as a function of atomic percent nitrogen. The mechanical properties, elastic modulus and hardness, of the films were tested using a Hysitron Triboscope nanomechanical test instrument. The nanotribological performance of the films was evaluated using a Nanoindenter II with scratch capability. Single and reciprocating nanowear scratches, 10 @micon@ in length, were performed at normal loads ranging from 50 to 750 micronewtons. An atomic force microscope (AFM) was utilized to characterize the nanowear tracks with respect to depth and amount of plowing of material. The AFM images revealed that the reciprocating nanowear test caused grooving of the films with little to no material removal. The chemical and structural information of the films were characterized by x-ray photoelectron spectroscopy (XPS) and x-ray diffraction, respectively. Results show as the nitrogen content of the films increases, the films become amorphous, which directly corresponds to a decrease in the mechanical properties as well as the nanowear resistance of the films.
FP-12 Study of Cryogenic Processing of Thin Metal Films
L. He (San Jose State University)
Cryogenic (LT) process has proven by previous study to increase Schottky contact barrier height, and reduce device reverse leakage current significantly. Metal-semiconductor-metal (MSM) photodetectors are widely used in the optoelectronic integrated circuit (OEIC) receivers because of their compatibility with the preamplifier for their planar integration scheme, the minimum number of processing steps, high performance, and low cost. InGaAs/InP is usually chosen for the long wavelength application. Though there is always a potential problem of high dark current in an InGaAs/InP MSM photodetector due to the lower barrier height from such a material. In recent study on Ag/InGaAs/InP contact, the Schottky barrier height was found to be as high as 0.64eV by LT process. This value is more than two times higher than that of the same contact obtained by room temperature process. Therefore, it is believed that the LT process could greatly enhance the performance of a MSM photodetector. In this work, the LT process on the property of thin metal films was investigated. This work extensively studied the electrical and micro-structural properties of several often used metal films including Au, Ag, Al, Pt, Pd, and Ni formed at LT. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and in-situ resistivity measurements were conducted. A computer simulation on the properties of the LT thin films was also conducted.
FP-13 Influence of Preparation Conditions on the Properties of Amorphous SiCN Films Prepared by ECR-CVD
D.H. ZHANG, Y. Gao (Nan Yang Technological University, Singapore); J. Wei (Gintic Institute of Manufacturing Technology, Singapore)
We report the properties of amorphous silicon-carbon-nitrogen (a-SiCN) films which were prepared using the industry-used electron cyclotron resonance chemical vapour deposition at different conditions and characterised by I-V, optical transmission, scanning electron microscopy (SEM), atomic force microscopy (AFM). The deposition rate of the films is found to increase with the microwave power. It peaks at a ratio of silane to the mixture of silane, methane and nitrogen around 30 and at a radio frequency bias of 100 V. The optical energy band-gap of the films increases with the gas ratio but decreases with radio frequency bias monotonically. The electrical conductivity, the hardness of the films and their surface roughness are sensitive to the preparation conditions. In addition, effect of substrate, including Si and glass, has also been studied. The films deposited on glass are mostly amorphous and have an intermediate layer between the films and substrate, while the films deposited on Si, however, show the sign of crystallisation. The change in the film properties is associated with the change in the incorporation of carbon and nitrogen, as verified by the XPS measurements.
FP-14 Effect of Elastic Stresses on Solid-state Amorphization of Zr/Co Multilayers
J.-Y. Huh, S.-J. Moon (Korea University, Korea)
Elastic stresses are often present in thin films deposited on a substrate and can influence both equilibrium and kinetic behaviors of the films. In this study, we examined the effect of externally applied stresses on the process of solid-state amorphization of Zr/Co multilayers. A total of four alternating Zr(600Å) and Co(400Å) layers was deposited on oxidized Si (100) wafers at room temperature in an electron-beam evaporation system. Three identical samples were attached to a three-point bending apparatus, by which three different types of external stresses (compressive, tensile and zero stresses) were applied to the multilayered films, and isothermal anneals for solid-state reaction were performed in vacuum at temperatures of 210, 230 and 270@super o@C. High resolution transmission electron microscopy and Auger electron microscopy were carried out to determine the extent of amorphization. Results showed that the amorphization process was enhanced drastically under external compressive stresses and were interpreted with respect to the grain boundary diffusion of Co in Zr layers.
FP-15 Study on Stress Measurement of PVD-coating Layer
H.H. Hirose (Kinjo college, Japan); T.M. Murotani, T.S. Sasaki (Kanazawa University, Japan)
The investigation on the residual stress of titanium carbide/nitride (TiCN) films in terms of the X-ray diffraction method is our purpose. However it is hard to measure the stress by the commonly used X-ray stress measurement, because the sin@super 2@psi@ method demands macroscopic isotropy from the specimen but the [111] orientation is observed for our evaporated TiCN film by PVD. Therefore, in this paper the X-ray stress measurement for [111] oriented films was analyzed by orientation distribution function (ODF) from pole figure and calculated values from considered fiber texture. Moreover, a relation of obtained values of residual stress and coating thickness of TiCN layer were discussed.
FP-16 Variation of Surface Morphology of Polyimide Film by Ion Beam Irradiation and Its Effect on Adhesion to Metal Thin Film
S. Hakamata (Kyoto University, Japan); N. Fujiwara (Sanwa Kenma, Ltd., Japan); A.M. Ektessabi (Kyoto University, Japan)
Irradiation of argon, oxygen and nitrogen ion beams onto polyimide films was performed and their surface morphology was analyzed by AFM. Copper thin films of 100 nm thickness were deposited on ion beam modified polyimide films using electron beam vapor deposition technique. Scratch test was carried out to investigate adhesion of copper thin film with polyimide film. The acceleration voltages of argon, oxygen and nitrogen beam were 0.5, 1.5 and 3.0 kV, and the doze was chosen between 3.3x10@super 14@ and 1.0x10@super 16@ ions/cm@super 2@. It was confirmed by AFM that surface roughness of irradiated polyimide films were higher than that of non-irradiated one. The highest value of surface roughness Ra among the samples made at constant doze of 9.9x10@super 15@ ions/cm@super 2@ was obtained at 1.5 kV acceleration voltage, with increase of 1.8 times as compared with non-irradiated polyimide. Close correlation between surface roughness of polyimide and that of copper thin film on polyimide was obtained, which assures formation of copper thin film with no gap between substrate and the thin film. This maximizes the contact surface that has effect on adhesion property. The scratch test showed the adhesion of copper thin film on irradiated polyimide film increases by 10-30 % compared with that of non-irradiated one. The adhesion of specimen made at acceleration voltage of 1.5 kV was the highest under the condition of constant doze. This result indicates the effect of surface morphology on adhesion and the potential of ion beam treatment to polymer-metal interface.
FP-17 The Effect of Deposition Rate on the Structure and Mechanical Properties of Sputtered Ta-Silicide Thin Films
Y. Makogon, E. Pavlova, S. Sidorenko (Ntuu Kpi, Ukraine); S. Dub (Institute for Superhard Materials, Ukraine)
Thin films 500 nm in thickness were obtained by magnetron sputtering from TaSi2 target in vacuum of 10-5 Torr. The films were deposited on a silicon substrate with two deposition rates: 0.1 nm/s and 1 nm/s. XRD, AES, SIMS and electrical measurements were used to characterize the films structure. The mechanical properties were studied using interrupted depth-sensitive nanoindentation experiments. By the first loading/unloading cycle the initial indent was formed. At reloading the indenter up to a h igher load, the deformation curve of the film at point loading was obtained. Two crystalline phases (Ta5Si3 and TaSi2) and small amount of the amorphous phase were revealed in the film obtained with 1 nm/s deposition rate. Thermal annealing in vacuum at 1170 K caused the rise of crystalline phase content in the film. Furthermore, a part of Ta5Si3 phase transformed into TaSi2. Electrical and mechanical properties of the films after annealing changed slightly.The films obtained with 0.1 nm/s deposition rate contain only the amorphous phase. Annealing in vacuum caused crystallization of amorphous phase. Mixture of two phases was revealed, with TaSi2 phase being prevailed. The annealing changed drastically the mechanical properties of the film. The hardness and elastic modulus increased significantly, the film became brittle and highly stressed. The effect of crystallization on the deformation curve of amorphous Ta-silicide films is discussed. It was found that decrease of the deposition rate leads to an incr ease of the O and C impurities content in the films. Contamination of the film by O and C atoms a during low-rate deposition causes the saving of the amorphous phase in the deposited films and decreases the rate of the crystallization during the subsequent annealing.
FP-18 Characterization of the CrN Coatings Oxidized at Elevated Temperatures
W.P. Hsieh, W.C. Wang, F.S. Shieu (National Chung Hsing University, Taiwan)
The microstructure and chemistry of CrN coatings oxidized in air at temperatures ranging from 300 to 800@super o@C for 60 min was analyzed by transmission electron microscopy (TEM), electron energy loss spectroscopy, X-ray diffraction and scanning electron microscopy. The CrN coatings were prepared by cathodic arc ion plating deposition on AISI 304 stainless steel. Cross-section TEM shows three distinct regions including the steel substrate, Cr interlayer and CrN in the as-deposited specimens, in which the CrN layer exhibits columnar structure and preferred orientation illustrated by the arced electron diffraction patterns. The surface morphology of the CrN-coated steel remains similar to the as-deposited specimens for those oxidized below 600@super o@C. Oxidation of the CrN-coated steel above 500@super o@C produces two new phases, Cr@sub 2@O@sub 3@ and Cr@sub 2@N, which are detected by X-ray diffraction, and the content of both phases increases with increasing temperature. In addition, the residual stress in the CrN coating is measured to be ~2.8 GPa from a curved thin strip and the unrelaxed thermal stress due to a difference in the coefficients of thermal expansion between CrN and steel is calculated to be 0.89 GPa.
FP-19 A Study of the Oxidation Behavior of TiN-coated Steel at Elevated Temperatures
L.Y. Horng, M.H. Shiao, F.S. Shieu (National Chung Hsing University, Taiwan)
TiN thin films were deposited by hollow cathode discharge ion plating on AISI 304 stainless steel. The oxidation behavior of the TiN-coated steel at elevated temperatures ranging from 300 to 700@super o@C for 30 min in air was investigated by energy filtering transmission electron microscopy, scanning electron microscopy and X-ray diffraction. It is found that the color of the TiN coatings begins to change from light to dark gold at 400@super o@C; however, the surface morphology of the TiN-coated steel remains similar to the as-deposited specimens for those oxidized below 500@super o@C. Noticeable depression along grain boundaries of the steel, which is closely related to the sensitization of the austenitic stainless steel, is observed on the surface of the TiN-coated specimens oxidized at above 600@super o@C and iron oxides such as Fe@sub 3@O@sub 4@ and Fe@sub 2@O@sub 3@ are both detected in the X-ray spectra. The two allotropic phases of TiO@sub 2@, anatase and rutile, are identified in the specimens oxidized below 600@super o@C and the content of anatase phase decreases with increasing temperature. Only the rutile phase is obtained in the specimens oxidized at 700@super o@C, which is higher than that predicted from the thermodynamic phase diagram.
FP-20 Effect of an Oxide Layer on the Microstructure and Adherence of TiN Coatings on AISI 304 Stainless Steel
M.H. Shiao, C.J. Wang, F.S. Shieu (National Chung Hsing University, Taiwan)
TiN thin films were prepared by hollow cathode discharge ion plating on AISI 304 stainless steel that is oxidized in air at 500@super o@C for 5 min. Characterization of the TiN-coated specimens was carried out by energy filtering transmission electron microscopy (TEM). Cross-section TEM shows three distinct regions including the steel substrate, oxide layer and TiN in the specimens, and many voids are present in the oxide layer near the oxide/steel interface. Electron diffraction indicates that the oxide layer which was measured to be ~20 nm is composed of g- and a-Fe@sub 2@O@sub 3@ phases and around the TiN/steel interface Ti@sub 2@N and Fe@sub 2@Ti are detected besides TiN. Tensile test of the TiN-coated specimens shows that the TiN coatings with an oxide layer have poorer adhesion than those without and failure of the coatings with the oxide layer occurs along the oxide/steel interface.
FP-21 Investigation of the Aluminium Oxidation in an Oxygen Plasma Excited by Microwaves
A. Quade, H. Wulff, H.J. Steffen, T.M. Tun, R. Hippler (University of Greifswald, Germany)
Al-coatings of about 50 nm thickness were deposited by thermal evaporation on Si-wafers. The changes of the surface of the Al-layers during plasma treatments in a 2.45 GHz microwave discharge were investigated. Plasma conditions were changed by gas flow, power and the substrate temperature and their influence on the properties of the developed aluminium oxide was studied using grazing incidence x-ray reflectometry (GIXR), grazing incidence x-ray diffractometry (GIXRD), XPS, IR-spectroscopy and AFM. At grazing incidence all x-ray techniques become surface sensitive. GIXR measurements give the thickness, density and roughness of the layers and substrates. The chemical composition and structure of the oxide layers were determined by GIXRD, XPS and IR. For topography observations AFM was used. It was observed that plasma treatments lead to reactions at low temperatures (<300@super o@C) where thermal treatments show no noticeable effect. Plasma causes an increase of the upper alumina in dependence on the plasma conditions as well as the substrate temperature. Variations of incident microwave power effect the thickness and morphology of the oxide films. With increasing oxygen concentration the formation rate of alumina increases. The developed oxide is x-ray amorphous. The crystallization behaviour was investigated by means of in situ GIXRD during post annealing in dependence on different plasma treatments.
FP-22 A Formation Mechanism for Macro Particles in Arc Ion-plated TiN Films
M.H. Shiao, F.S. Shieu (National Chung Hsing University, Taiwan)
Characterization of macro particles in TiN films prepared by an arc ion-plating method on AISI 304 stainless steel was carried out by energy filtering transmission electron microscopy. The result shows that most of the macro particles have the shape of a bud, in which located at the bottom center is equiaxial polycrystalline Ti metal. On the basis of the analysis, a model describing the formation of macro particles in the arc ion-plated TiN is proposed. Once emitted from the cathode, the liquid Ti droplets react with nitrogen during their travel to the substrate and form a thin layer of titanium nitrides on the surface of the droplets, resulting in a core-shell structure. As a result of the high-melting out shell, flattened torus voids are produced, upon impact on the substrate, beneath each particle and cause shadowing of the ion flux during deposition. Subsequent growth of TiN follows the orientation of the titanium nitride nuclei in the shell to form a radial type structure, until coalescence with the regular TiN columns perpendicular to the substrate surface occurs. Selected area diffraction patterns of the macro particles indicate that the out shell consists of TiN@sub 0.26@, a-TiN@sub 0.3@ and Ti@sub 2@N, in addition to TiN.
FP-23 Tunneling Probe with Diamond Tip for Characterization of Thin Films
N. Novikov, O. Lysenko, V. Grushko, N. Zaika (V.Bakul Institute for Superhard Materials, Ukraine)
Recent development in Scanning Probe Microscopy (SPM) allow to a complex analysis of thin films. Measuring the topography of an indent using SPM and combining this information with a load-displacement nanoindentation data is one of the most recent developments in this growing field. Scanning tunneling microscopes or atomic force microscopes are used for imaging of surfaces before and after indentation. Simultaneously these microscopes with diamond tip have been used for indentation (atomic force microscopes are preferred because of their versatility). The disadvantage of the tunneling current measurement method is its limitation in studying materials with low conductivity, for example c-BN films. This problem can be solved by increasing the tunneling probe sensitivity to the tunneling current up to the 10-12 A. However in the case of traditional using a diamond tip for both indentation and scanning the obstacle of the low conductivity of a diamond arises. For a solution of this problem semiconducting diamond monocrystals were synthesized. A unique feature of this instrument is the ability to noncontact measure acoustic emission (AE) signal during indentation and sliding on thin films using tunneling effect. A three-sided pyramidal (Berkovich) semiconducting diamond tip has been used to obtain a load-displacement curve with residual depth of the order of 0.1 nm. The same tip has been used for sliding and generating of topographic images, while the sample remains stationary. A second tip is used for noncontact measuring of acoustic emission waves during indentation and sliding. The results obtained on c-BN are presented to illustrate the method.
FP-24 Modeling of Contact Stress Field in Oxide Layer of Sliding Electrical Contact Copper/Steel
Z.H. Zaidi, A.S. Senouci, K.J.C. Chin (Faculté des Sciences SP2MI, France); J.F. Frene (Faculté des Sciences SP2M, France)
The electrical current trough a sliding contact copper/steel is a parameter which have an important influence on the oxidation of the contact surfaces. The current intensity and its polarity induce an electrical field in the contact. This electrical field enhances the metal anode oxidation, and reciprocally the growth of the oxide layer increases the field intensity. The analysis of the contact electrical resistance shows a cyclic phenomenon of the growth and breaking of oxide layer. The contact stress field du to the applied normal load N and to the tangential force Ft=µN in the oxide layer is modeled and determined to estimate the maximum shear stress. The objective of this study is to present the tribological behavior of couple, to model the stress field distribution and to explicit the layer growth and breaking by the mechanical and electrical mechanisms in electrical sliding contact.
FP-25 Optical Constants of CN@sub x@ Thin Films from Reflection Electron Energy Loss Spectroscopy.
F. Barreca, A.M. Mezzasalma, G. Mondio, F. Neri (INFM and University of Messina, Italy); S. Trusso (Istituto di Tecniche Spettroscopiche del CNR, Italy); C. Vasi (CNR, Italy)
Electron energy loss spectroscopy (EELS), in both transmission (TEELS) and reflection (REELS) geometries, can provide a powerful tool to obtain the optical constants of a material over a very large energy range. Calculation of the optical constants from EEL measurements is a fairly complicated but well established procedure. In fact with the aid of appropriate numerical procedures the optical constants can be obtained over a wide energy range, larger than the one allowed by common optical techniques. After eliminating the elastic peak and background contributions, a spectrum of singly scattered electrons, built up by bulk and surface processes, is obtained. Separating the two contributions, under the assumption of a small momentum transfer, the the optical constants can be obtained through a Krames-Kronig transformation of the bulk loss function. Other physical quantities related to the dielectric constant, such as reflectivity and joint density of states (JDOS) can also be obtained. In this work we present the EELS deduced optical constants, up to 50 eV, for some CN@sub x@ thin films deposited by pulsed laser ablation of graphite targets in a controlled nitrogen atmosphere. The results can be compared with both experimental data, deduced from conventional optical measurements, and first principle theoretical model predictions.
FP-26 The Study of Mechanical Properties of Amorphous SiCN Films
K.J. Ma, C.T Wong, C.L. Chao (Chung-Cheng Institute of Technology, Taiwan); H.C. Lo (National Taiwan University of Science and Technology, Taipei, Taiwan); K.H. Chen (Academia Sinica, Taipei, Taiwan); L.C. Lin (Academic Sinica, Taiwan)
Ion beam sputtering from SiC targets assisted with an atomic nitrogen source were employed to deposit amorphous SiCN films in the presentstudy.  It was found that atomic nitrogen source significantly enhanced the incorporation of nitrogen in the SiCN films and promoted the formation of Si-N and C-N bonds, which lead to a higher hardness(H) and elastic modulus(E).  High nitrogen content (61%) amorphous SiCN films attain a hardness H around 20 GPa typical of inorganic ceramics, but have Young’s  modulus values E around 79 Gpa significantly lower  than ceramics.  The corresponding H/E ratios (~0.25) are relatively high and their values are more similar to that for hard polymers than to those for ceramics.  This compressive residual stress amorphous SiCN films have great potential to be applied to tribological application.   @paragraph@ The compressive stresses of amorphous SiCN films were found to increase with  the deposition temperature.  Post treatments such as rapid thermal annealing and laser irradiation were carried out to reduce residual stress.
FP-27 Nanoindentation with a Knoop Indenter
L. Riester, P.J Blau, K. Breder (Oak Ridge National Laboratory)
Nanoindentation is a reliable method for measuring mechanical properties on smooth, flat specimens of most materials. Because it is difficult to manufacture a nearly perfect diamond tip for the Nanoindenter, some tip geometries may be better suited for measurements of mechanical properties at the nanometer level than others. This study concerns itself with the use of a Knoop tip on the Nanoindenter. The response of assorted bulk materials, layered structures and thin films to Knoop indentation was examined. Sample stiffness during indentation and data from the loading and unloading history were compared to measurements based on scanning electron microscope images of residual indenter impressions.
FP-28 Silicon Oxidation in the Au/Si and Au/a-Si/Si Systems.
B.A. Julies, D.P. Adams (University of the Western Cape, South Africa)
Research has recently been focused on finding ways and means of forming SiO@sub2@ of reasonable thickness (1000Å or more) at relatively low temperatures. A system of special interest is the Au-Si structure as it exhibits low temperature oxidation behavior when heated in an oxidizing atmosphere.@paragraph@When an amorphous Si layer is introduced between the Au and Si(100) substrate to form a Au/Si(a)/Si(100) structure Si atoms from the amorphous layer diffused through the Au layer and oxidized on the surface. The introduction of the amorphous Si resulted in the lowering of the melting point of Au as well as the enhancement of oxidation for specific amorphous Si thicknesses.@paragraph@ Rutherford Backscattering Spectrometry (RBS) and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-Ray Spectroscopy (EDS) have been used to investigate the structures and oxidation mechanisms of the two systems.
FP-29 The Electrical and Interfacial Properties of CVD-W/p-Si@sub 0.83@Ge@sub 0.17@ Schottky Contacts
Y.C. Jang, K.S. Kim, H.J. Kim, D.O. Shin, S.P. Youn, K.C. Roh, Y.H. Roh, K.-H. Shim, N.E. Lee (Sungkyunkwan University, Korea)
Si@sub 1-x@Ge@sub x@/Si heterostructures are of great interest because of their potential application in heterojunction devices and formation of metal contacts on Si@sub 1-x@Ge@sub x@ plays an essential role in the various devices utilizing Si@sub 1-x@Ge@sub x@/Si including heterojunction bipolar transistors (HBT), modulated doped field effect transistors, quantum well metal-oxide semiconductor field effect transistors, and photodetectors. In recent years, electrical properties of W schottky contacts on Si@sub 1-x@Ge@sub x@ alloys formed by sputtering were measured@footnote 1@. However, electrical properties such as schottky barrier height were strongly dependent upon the W deposition conditions such as pressure during sputtering. @paragraph@In this study, we investigated the electrical properties of CVD-W/p-Si@sub 1-x@Ge@sub x@(x=0.17) schottky contacts in which W contacts are formed by chemical vapor deposition (CVD). Fully-strained 90 nm-thick p-type Si@sub 1-x@Ge@s! ! ub x@(x=0.17) epitaxial thin film with the boron concentration of 5x10@super 17@ cm@super -3@ was deposited on n-type Si(001) substrate at the substrate temperature of 650@super o@C by low-pressure chemical vapor deposition (LPCVD) utilizing SiH@sub 4@, GeH@sub 4@, B@sub 2@H@sub 6@, and H@sub 2@ gases. W layers to Si@sub 1-x@Ge@sub x@(x=0.17) alloy were grown by low pressure chemical vapor deposition using the WF@sub 6@ precursor and H@sub 2@ as a carrier gas as a function of the growth temperature, T@sub s@ = 350 - 500@supero@C. W schottky contacts with various sizes from 0.2 mm@super 2@ to 0.6 mm@super 2@ were defined by photolithography and selective etching. Then, ohmic contacts on Si@sub 1-x@Ge@sub x@(x=0.17) were formed by Al sputtering using a shadow mask followed by the annealing at 400@super o@C. Electrical properties of the CVD-W/Si@sub 1-x@Ge@sub x@(x=0.17) schottky diodes were characterized by the current-voltage (I-V) and capacitance-voltage (C-V) measurements. Th! ! e structural and chemical properties of CVD-W/Si@sub 1-x@Ge@sub x@(x=0.17) interfaces were analyzed by x-ray diffraction (XRD), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS). The correlation between electrical and structural properties of their interfaces will be discussed. Footnote@@sub 1@ F. Meyer, M.Mamor, and V.Aubry-Fortuna, et al., J.Electron.Mater.25,11 (1996)
FP-30 Microtensile Experiments of Titanium Monoxide Thin Films on Copper
M.E. Pilleux, C. Avila, V.M. Fuenzalida (Universidad de Chile); M. Ignat (CNRS-ENSEEG, France)
Titanium monoxide films have been grown by physical vapor deposition on polished copper substrates in high vacuum. The deposition method consisted in the evaporation of TiO powders from a resistively heated tungsten boat. The as-deposited films were analyzed using x-ray photoelectron spectrosmetry (XPS) and Auger electron spectrometry (AES), showing that the film completely covered the underlying substrate. The film thickness was in the range of 20-150 nm. The mechanical stability of the films was investigated using in-situ microtensile experiments in a scanning electron microscope (SEM). The evolution of the damage activated by the pulling of the film substrate was analyzed and the critical parameters of the film behavior were determined.
FP-31 The Potential of Laser-acoustics for Testing Thin Films in Practice
D. Schneider, T. Schwarz (Fraunhofer Institute Material and Beam Technology, Dresden, Germany); T. Schuelke (Fraunhofer Resource Center Bradley University, Peoria, Illinois); B. Schultrich (Fraunhofer Institute Material and Beam Technology, Germany)
The laser-acoustic technique has been proved to provide useful information of thin films and material surfaces. It yields the elastic modulus of films that depends on the micro-structure of the film, determines and correlates with important mechanical properties of the coated material such as hardness, wear behavior, adhesion and residual stresses. Some advantages the laser-acoustic technique can claim are the follows: - Super-hard films can be tested without restriction. - Ultra-thin films with thickness down to less than 10 nm can be tested. - The anisotropic behavior of multi-layer films can be taken into account. - It is sensitive to reduced adhesion. - It can sensitively characterize damage layers due to the finishing process of surface, which has been demonstrated for semiconductor materials. - The test is non-destructive. - The test results show remarkable reproducibility. These capabilities encouraged the development of a new device that can be applied in research and industry as well. The performance and operation of the new device are explained. Results are presented for testing ultra-thin film, hard-coatings and machining layers.
FP-32 Superlattice Effects on the Amorphization of Ni-Ti Multilayers
A.F. Jankowski (Lawrence Livermore National Laboratory)
The parameters of sputter deposition influence the energetics of the growing film. Deposition conditions are found for an epitaxial growth when alternating Ni and Ti layers. Observations using transmission electron microscopy indicate that the as-deposited, crystalline multilayer structures are temperature sensitive. Upon heating the multilayer films, a solid-state amorphization (SSA) reaction is found to occur nucleating at the Ni-Ti interfaces. Amorphization is expected to originate at interface sites of composition and crystalline disorder. A temperature dependence to the onset of the SSA reaction is measured using differential thermal analysis. SSA occurs in short period Ni-Ti multilayers at higher temperatures. X-ray diffraction characterization indicates that lattice strains in the Ni and Ti layers vary with the multilayer spacing. The interfaces appear to become less coherent as the layer pair spacing increases from very short periods. A model is proposed that correlates the energetic barrier to amorphization in crystalline multilayers with the loss of (interfacial) lattice stability. This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48.
FP-33 Behavior of the Pulsed Ion Nitrided AISI 4140 Steel / CVD TiN Coatings Tribological Pair
M.H. Staia, A. Fragiel (Central University of Venezuela); S.P. Brühl, J.N. Feugeas, B.J. Gomez (IFIR, Argentina)
The aim of the present investigation was to determine the wear behavior of a pulsed plasma nitrided AISI 4140 steel. Wear tests were performed using a pin-on-disc configuration with a sliding speed of 0.1m/s, 5 N load and 700 m sliding distance. The tests were carried out at room temperature in air, without lubrication, by employing two different pins materials (AISI 1086 and CVD TiN) on unitrided and nitrided AISI 4140 discs.The surface topography of the wear scars of samples and pins have been determined by using both scanning electron microscopy and 3D stylus profilometry. Different wear mechanisms were detected such as abrasion, adhesion and oxidational wear for the pairs under study. Results have showed an improved wear resistance of the nitrided samples in any experimental settings.
FP-34 Study of Interfacial and Electrical Properties of TiN/TaN Heterostructures
P. Nagar (University of South Alabama); V. Mangasuli, M. Shamsuzzoha (University of Alabama); A. Kumar (University of South Alabama)
TaN films are extensively used in microelectronics applications such as resistors and capacitors because of their long term stability and low thermal coefficient of resistance. They are high heat generators that when combined with a high structural defect content and high compressive residual stress can alter interface structure and properties over long service lives. In our studies we have used the multilayer combinations of TaN and TiN to address this issue. The TiN layer acts as a diffusion barrier between the TaN layer and the substrate. We have deposited hetero-structures of TaN and TiN using the pulsed laser deposition technique under the optimized conditions. The structural and surface morphological properties have been evaluated by X-ray diffraction and scanning electron microscopy. The interfacial properties have been studied by the transmission electron microscopy. The films are electrically characterized by the four-probe resistivity technique. The details of the investigations are presented in the paper. This research was supported by NSF- DMI I-9900459
FP-35 Effect of Substrate Roughness Induced by Sand Blasting Pressure upon adhesion of WC+Co THERMAL sprayed coatings
A. Roman, J. Lesage, D. Chicot, G. Mesmacque (University of Science and Technology of Lille, France); M.H. Staia (Central University of Venezuela)
WC+Co thermally sprayed coatings are very often used for their high hardness and resistance to abrasion and erosion induced wear. Several compositions ranging mostly from 12 to 18 % Co are commercially availaible and numerous studies have reported the changes in hardness and wear properties in relation to these compositions. A great number of parameters influences functional as well as adhesive properties of thermal sprayed coatings. Among them the preparation of the substrate by grit blasting before spraying is of first importance. The grit blasting generates sufficient surface roughness which ensures mechanical anchoring between the coating and the substrate. By varying the grit blasting pressure between 50 to 90 Psi, a surface roughness ranging from 9 to 12 microns was obtained. It was shown that adhesive properties of WC-Co coatings, as measured by interfacial indentation, are strongly affected by roughness variations. As the surface hardening of the substrate is also dependent on the grit blasting pressure, we have shown that the explanations of this behaviour have to take into account this aspect.
FP-36 Microstructural and Tribological Characterization of a A-356 Aluminium Alloy Superficially Modified by Laser Alloying
M. Cruz, M.H. Staia (Central University of Venezuela); N.B. Dahotre (University of Tennesses Space Insitute)
Microstructure and wear of an A-356 aluminium alloy superficially modified by laser alloying were studied. A 2000 W Nd-YAG laser was employed for the alloying using a powder composed of 96% WC, 2%Ti and 2%Mg and displacement speeds of 100, 200, 300 and 400 cm/min. Optical (OM) and Scanning Electron Microscopy (SEM) were used to examine the morphology of the superficial and the heat affected zones. From the surface to the core and by steps of 100 microns, a series of 15 indentations were performed on a cross section of the laser alloyed material. Wear properties were studied using the pin on disc method with pins made of WC or 52100 steel under a load of 5 N. Friction coefficients as well as wear volumes are reported. It was shown that the steel pins are subjected to adhesive wear and the WC pins to adhesive and abrasive wear.
FP-37 Role of Hydrogen Upon Adhesion of NiCr Thermal Sprayed Coatings
D. Chicot, J. Lesage (University of Science and Technology of Lille, France); P. Araujo (University of Science and Technology of Lill, France); M. Zampronio (Universidade Estadual de Maringa, Brazil); P.E.V. de Miranda (Universidade Federale de Rio de Janeiro, Brazil)
Hydrogen embrittlement is known for many years. Different theories explain how hydrogen plays the role of an accelerator for fracture when introduced into the material either during its elaboration or during its service as a mechanical part. In this latter case, the presence of a barrier to introduction of hydrogen into the material may delay or even impede the embrittlement process. It was studied previously the physical aspects of hydrogen adsorption and diffusion into a NiCr thermal sprayed coating. The present study is devoted to the mechanical aspects of hydrogen contamination of this type of coating, in particular coating adhesion on a low carbon steel substrate. It was found that, besides the embrittlement of the coating, adhesion is also affected since the critical load necessary to initiate a crack at the interface is severely reduced. Using an apparent interfacial toughness concept it was also possible to point out the effect of the residual stresses in relation to the coating thickness.)
FP-38 Effect of Thermal Solicitations Upon Adhesion of a HVOF NiCr Sprayed Coating
J. Lesage (University of Science and Technology of Lille, France); M.H. Staia (Central University of Venezuela); D. Chicot (University of Science and Technology of Lille, France); C. Godoy (Universidade Federal de Minas Gerais, Brazil); P.E.V. de Miranda (Universidade Federale de Rio de Janeiro, Brazil)
Thermal sprayed coatings are most often used to resist wear or as thermal barriers. In some situations they may have to resist to combined solicitations such as corrosion and wear at high temperature. Ni-base thermal coatings are being used successfully in this case. It has been demonstrated that adhesion may be modified after a thermal treatment. For exemple, a substantial increase in adhesive properties was obtained after annealing of an HVOF chromium carbide thermal sprayed coating. Using the interfacial indentation method we have studied the influence of an annealing treatment upon adhesion of NiCr coatings for a range of thickness between 200 to 500 microns. It was confirmed that annealing improves adhesion in a great extent. Thermal cycling between room temperature to 900 @super 0@ C (x 5 times) and thermal shocks consisting in heating the samples to 900 @super 0@ C then quenching them in oil at room temperature (x 5 times) were also studied after the annealing treatment. It was found that no deleterious effect is obtained after such treatments since the critical load necessary to initiate a crack at the interface was nearly the same in both cases. On the contrary, crack propagation at the interface was slowed down after thermal solicitations. This behavior is discussed and related to the role played by the residual stresses in the coating.)
FP-39 Investigation of Threshold Load for Yield Initiation in Coating-substrate Systems
K.C. Tang (IDAC Limited, England); R.D. Arnell (University of Salford, England)
Due to the numerous possible combinations of coating/substrate materials and configurations, the accurate computation of the yield initiation and the complex mode of plastic deformation in such systems can only be made possible by means of numerical methods.@paragraph@ In this study, the threshold loads corresponding to the initiation of plastic deformation in both the coating and substrate under normal contact with a deformable indenter are investigated using finite element methods. A wide range of practical values for the ratios of coating thickness to radius of indenter, t/a, coating to substrate elastic modulus E@sub c@/E@sub s@, and coating to substrate yield strength, Y@sub c@/Y@sub s@ are analysed. This leads to an operational envelope for the coating and substrate materials subjected to similar indentation loading, within which the materials will deform elastically.
FP-40 Diagnostics of Annealing Behavior of Cubic Boron Nitride Films by In Situ IR Reflection Spectroscopy
P. Scheible, A. Lunk (University of Stuttgart, Germany)
Layers of almost pure cubic boron nitride (c-BN) have been deposited in a hollow cathode arc evaporation device on silicon and on titanium nitride (TiN) coated tungsten carbide (WC) substrates. The internal stresses of 400-600 nm thin films deposited are in the order of 10 GPa. The layer growth and the annealing experiments are analyzed in situ by infrared reflection spectroscopy. The optical setup can be used either as infrared spectroscopic ellipsometer (IRSE) in a rotating analyzer configuration as well as polarized infrared reflection spectrometer (PIRRS). Spectra can be taken every 10 seconds. They are sensitive to determine the phase of the growing film due to different phonon absorption frequencies of hexagonal BN (h-BN) and c-BN and can also be used to determine the film thickness. @paragraph@ The annealing behavior of c-BN films was investigated in situ with PIRRS and IRSE on silicon and TiN coated WC substrates. The phonon frequency is correlated to stress in c-BN films. The frequency shift observed during annealing experiments is influenced by different processes: @paragraph@ a) frequency shift to lower values due to temperature dependence of phonon vibrations, @paragraph@ b) frequency shift by stress relaxation, @paragraph@ c) frequency shift induced by stress resulting from different thermal expansion coefficients of film and substrate. @paragraph@ The temperature dependence of phonon vibrations is an indicator for high temperature behavior of the elastic constants and the hardness of c-BN films. A relaxation of the stress in c-BN films should occur at a characteristic temperature and is followed by an irreversible frequency shift to lower values. By comparing spectra before and after annealing it is possible to specify the size of both effects. A frequency shift due to thermal stress was identified by comparing the spectra of films on different substrates.
FP-42 Film Formation Mechanism During Reactive Magnetron Sputtering of Alloys
L.R. Shaginyan (Institute for Problems of Material Science, Ukrainian National Academy of Science, Ukraine); M. Mishina (Institute of Physics Academy of Sciences of the Czech Republic); J. Musil (University of West Bohemia, Czech Republic); L. Jastrabik (Institute of Physics Academy of Sciences of the Czech Republic)
The mechanism of formation of the films, deposited by magnetron reactive sputtering of W-30at%Ti alloy in Ar-N@sub 2@ mixture, was studied. The dependencies of the film composition, growth rate (V@sub g@), structure and microhardness as like the gas phase composition during the sputtering, on the working gas composition, substrate bias and discharge current, were investigated. @paragraph@ The mass-spectrometry of the sputtered particles revealed the presence of TiN@super +@ and WN@super +@ ions. Relative concentrations of TiN@super +@ /Ti@super +@ and WN@super +@ /W@super +@ increased monotony with increasing of %N@sub 2@ in Ar-N@sub 2@ mixture and achieved TiN@super +@ /Ti@super +@ ~10% and WN@super +@ /W@super +@ ~30% at %N@sub 2@ =60%. Investigation of the composition of the films deposited in identical conditions showed the gradual decrease of the W and increase of N content in the film with increasing of %N@sub 2@ up to 60%. Simultaneously the Ti content in the film increased with increasing of %N@sub 2@ up to 20% and than decreased gradually. The dependence of the V@sub g@) of the film on the %N@sub 2@ had the same trend as the Ti content in the film. The main feature of this dependence was that the V@sub g@) increased as the N@sub 2@ was added in working gas and exceeded the V@sub g@) of the film deposited in pure Ar. When the %N@sub 2@ in Ar-N@sub 2@ exceeded 20% the Vg started to decrease. Correlated decrease of Ti/W and N content in the film was observed with the increase of the substrate bias from -100 up to -200 V. @paragraph@ All these observations including the structure investigations, allowed to suggest the mechanism of formation of the composition and structure of reactively sputtered films, in which nitride molecules play much more significant role than it was considered earlier.