Ion Assisted Deposition and Ion Beam Technologies
Thursday, April 13, 2000 1:30 PM in Room Royal Palm Salon 1-3
B5-1 Energy-Assisted Deposition of Hard Thin Film Coatings
J.S. Colligon (Manchester Metropolitan University, United Kingdom)
A brief review of the various present-day techniques for energy-assisted deposition of hard thin film coatings is given. The role of the added energy is discussed and examples are given showing the improved adhesion, control of stress, increase in density, formation of novel alloys and phases and control of film microstructure that can now be attained. In particular, work on diamond and diamond-like films, multi-component nitrides and carbides and boron-nitride films is presented. Recent results on multilayer coatings and on the new nanocomposite mixed nitride coatings, which can have hardnesses approaching that for diamond, are discussed. Current models, proposed to explain the formation and hardness of these nano-structured materials, are reviewed. Finally some future prospects for these coatings and areas which need further study are identified
B5-3 Textured Titanium Oxide Thin Films Produced By Vacuum Arc Deposition
S. Mändl, G. Thorwarth, B. Rauschenbach (Universität Augsburg, Germany)
Titanium oxide films have a wide range of applications, due to their outstanding optical, electrical and chemical properties. Another promising application, for their biocompatibility and hemocompatibility, is as a protective surface coating for biomedical implants. Vacuum arc deposition is a promising method as it allows high deposition rates, combined with a high ionization rate and, hence, easily controlled deposition energy. @paragraph@ In this report we present results of vacuum arc deposition of titanium oxides on silicon (100) and (111), without and with applying high voltage pulses of 5 and 10 kV to the target. A titanium cathode in oxygen atmosphere was used to produce the titanium and oxygen ions. Stoichiometric TiO2 or slightly understoichiometric TiO@sub 2-x@ (x < 0.5) was obtained, depending on the oxygen pressure, at growth rates of more than 1 nm/s, as determined with Rutherford backscattering spectroscopy. For understoichiometric films a mixture of Ti@sub 3@O@sub 5@ and rutile (TiO@sub 2@) was observed with X-ray diffraction, whereas pure rutile was found for TiO@sub 2@ films. Additionally, a strong texture, with the rutile and Ti@sub 3@O@sub 5@ <110> direction parallel to the Si <111>, facilitated by a small lattice mismatch of 3%. This texture was observed for both substrate orientations, indicating a predominance of substrate influence over the surface free energy. While applying a negative d.c. bias or high voltage pulses to the substrate, a loss of texture was observed. No intermediate film orientation, minimising the radiation damage correlated with the ion bombardment was observed. Apparently, for the rutile on silicon system, the substrate influence is the only factor to influence the thin film orientation.
B5-4 High Energy Metal Ion Beam Assisted Deposition of Cr@sub x@N on Aluminum Substrates
T. Dennin, J.J. Moore (Colorado School of Mines); J. Treglio (ISM Technologies); A.J. Perry (A.I.M.S. Consulting, Switzerland)
The use of physical vapor deposition (PVD), specifically ion beam assisted cathodic arc evaporation, historically has deposited thin films of superior quality onto substrates at temperatures above 200@super o@C. For that reason, the substrate must have a high-tempering temperature otherwise the deposition process will deteriorate the mechanical properties of the substrate. The need for highly adhering, wear resistant coatings on low-tempering temperature substrates is the next logical step in the evolution of thin film deposition. In addition, the deposition of wear resistant coatings onto soft substrates such as aluminum alloys requires deposition temperatures below 200@super o@C. @paragraph@ Using the technique of high-energy ion beam assisted cathodic arc evaporation of Cr@sub x@N on 7075-T6 aluminum substrates, it has been determined that thin films of Cr@sub x@N, with high adherence and good wear characteristics, are possible to be deposited at low temperatures (i.e. below 150@super o@C for 4 hrs.) The thin films of Cr@sub x@N appear dense under examination in the scanning electron microscope (SEM), but have a definite crystalline texture using x-ray diffraction analysis. This technique has been shown to lower the residual stresses in the thin film. @paragraph@ The paper will discuss the properties of these wear resistant Cr@sub x@N films deposited onto 7075-T6 Al substrates.
B5-5 PBII Processing of Dielectric Layers : Physical Sspects, Limitations and Experimental Results
A. Lacoste, F Le Coeur, Y. Arnal, J. Pelletier (Centre National de la Recherche Scientifique, France)
Processing of dielectric layers using plasma based ion implantation technique (PBII) has general implications in terms of plasma specifications and pulse characteristics. In particular, the different aspects of the processing of dielectric layers are discussed as functions of plasma density, pulse duration, and layer characteristics (thickness and permittivity). Clearly, severe limitations (true implantation energy, arcing) may appear for high density plasmas as well as for long pulse durations when processing dielectric layers thicknesses in the mm range. Typical examples of ion implantation in dielectric materials are presented, e.g. the implantation of oxygen ions in polymer sheets (hydrophylic or adhesion treatments) and a comparative study of nitrogen implantation in silicon wafers and polysilicon on glass. The experimental results demonstrate the possibility of processing dielectric layers with the PBII technique, but with severe limitations resulting from the process itself.
B5-7 Titanium Nitride and Titanium Carbo-nitride Coatings Deposited by a Novel PIIP-MOCVD Process
A.M. Peters, M.A. Nastasi, B.W. Taylor (Los Alamos National Laboratory)
The focus on this research is the development of Ti-N and Ti-C-N coatings by using a novel CVD-plasma immersion ion processing process using the tetrakis-dimethylamido titanium (TDMAT) precursor. Coatings were deposited at various temperatures and substrate bias levels on substrates of (100) silicon, M2 tool steel, carbon and molybdenum. Wear resistance, residual stress, nanohardness, thickness and composition were measured using a variety of techniques including pin-on-disk, bending beam, nanoindetation, profilometry and Rutherford backscattering spectroscopy, respectively. Results are presented.
B5-8 Low Energy Ion-Beam-Assisted Deposition of Transition Metal Nitride Thin Films on Silicon
C.-H. Ma (University of Illinois, Urbana); J.H. Huang (National Tsing Hua University, Republic of China); H. Chen (University of Illinois, Urbana)
Ion-beam-assisted deposition (IBAD) method was used to deposit transition metal (Ti, Zr, V and Nb) nitride thin films on Si(100) substrates. Two different transition metal crystal structures (hcp for Ti, Zr and bcc for V, Nb), ion energy (100V, 300V and 500V), ion beam incident angle (normal, and 45@super o@), and substrate temperature (25@super o@C and 300@supor o@C) were chosen as the processing variables. After deposition, x-ray diffraction, x-ray photoelectron spectroscopy (XPS), cross-sectional transmission electron microscopy (XTEM) and scanning electron microscopy (SEM) were employed to characterize the thin film microstructure. In both groups of the transition metal nitride (NaCl structure), the (111) preferred orientation is dominant at low ion beam incident energy. The preferred orientation changes from (111) to (200) as the ion beam energy increases and over a threshold energy (~300V) with a normal incident angle; this is attributed to the ion channeling effect. Our results seem to show that the source crystal structure has nothing to do with the preferred orientation of the reacted films. * Work supported by the U.S. Department of Energy.
B5-9 Thin Film Fabrication of SiO@sub 2@ and SiN by Ion-Beam Assisted Deposition (IBAD)
N. Capps, D. Carter, G. Roche (Advanced Energy Industries)
Incorporation of ion beam technology into sputtering or reactive sputtering processes can yield enhanced film qualities, higher deposition rates, and more stable process behavior. IBAD studies have been carried out on silicon dioxide and silicon nitride using a magnetron sputtering cathode for production of silicon species and a gridless ion source for oxygen or nitrogen. Hysteresis behaviors, film hardness, optical qualities, and deposition rates were measured for ion-beam assisted deposition schemes and compared to those of reactive sputtering schemes to elucidate benefits provided by ion beam treatments. These results are interpreted and mechanisms of observed changes in film properties or process behavior are proposed.
B5-10 Trimming the Thickness Gradients of Gas Permeable SiO@sub 2@ Layers with Different IBAD Conditions
M. Frietsch, J. Goschnick (Forschungszentrum Karlsruhe GmbH, Germany)
Ion Beam Assisted Deposition (IBAD) was used to produce SiO@sub 2@ layers with a lateral thickness gradient on a gas sensor microarray, which was developed at the Forschungszentrum Karlsruhe. The microarray is based on some 100 nm thick SnO@sub 2@ or WO@sub 3@ layers deposited by HF-magnetron sputtering. Semiconducting metal oxides are used for gas sensors as their electrical conductivity is highly sensitive to the composition of the ambient atmosphere. By depositing a set of parallel electrode strips on top of the 4 by 8 mm wide sputtered metal oxide layer, the latter is currently subdivided into 38 sensor elements. In the last production step the microarray is coated with an inhomogeneous SiO@sub 2@ layer by IBAD using phenyl-triethoxy-silane as precursor. Owing to the thickness variation of the gas permeable SiO@sub 2@ coating from one side of the microarray to the other, the initially identical sensor elements are differentiated with respect to their gas response. Thereby the selectivity of gas detection for each sensor element becomes different and hence gas characteristic conductivity patterns are obtained with the microarray. @paragraph@ The inhomogeneous SiO@sub 2@ layers were produced by IBAD, since this method allows structuring of films during deposition because the film growth rate depends on the current density of the ion bombardment. With the aim of optimizing the selectivity variation of the sensor elements two different set-ups were tested. Two types of ion sources were used to obtain different shapes of ion beams in order to vary the ion current density across the microarray resulting in SiO@sub 2@ membranes with different thickness gradients. Furthermore, different positions of the microarray with respect to the ion beam were tested. The influence of the energy of the bombarding ions and of the precursor partial pressure on the properties of the deposited layers was investigated. The layers were examined with different surface analytical methods in order to determine the chemical composition and thickness of the layers, as well as the thickness gradient. SiO@sub 2@ layers with different thickness gradients from approx. 5 to 50 nm across the 8 mm wide microarray were produced and their influence on the sensing properties upon exposure to various gases was investigated.