ICMCTF2004 Session B4: Ion Beam Technologies

Friday, April 23, 2004 8:30 AM in Room Golden West

Friday Morning

Start	Invited?	Item
8:30 AM	Invited	B4-1 Microstructural and Surface Morphological Evolution at the Atomic Scale during Sputter Deposition of TiN: a HR-TEM, XRD, STM, and Modeling Study J.E. Greene, S. Kodambaka, S.V. Khare, V. Petrova, I. Petrov (University of Illinois at Urbana-Champaign) Polycrystalline TiN and related transition-metal (TM) nitride films, typically deposited by magnetron sputtering, are used as diffusion barriers in microelectronics as well as hard, wear, and corrosion resistant coatings in mechanical and optical applications. Since cubic TM nitrides are highly anisotropic, control of preferred orientation is essential. We employ a combination of XRD, TEM, and HR-XTEM to show that TiN layers grown at low temperatures (T < 450°C) exhibit competitive texture evolution with a columnar 111 texture eventually becoming dominant. The columns are narrow, facetted, and porous. Higher T or the use of high incident ion/Ti flux ratios (> 5) with low ion energies (20 eV) in the magnetically-unbalanced magnetron mode result in non-competitive growth with a fully dense complete 002 orientation from the initial monolayer. Kinetic Monte Carlo (KMC) modeling, assuming that the activation energy Es for surface diffusion and the Ehrlich barrier Eb at descending step edges are larger on 111 than on 002, provides a qualitative understanding. Quantitative modeling requires a full set of adatom transport and surface site energies: Es, Eb, orientation-dependent step edge energies and stiffnesses, kink energies, and adatom formation energies. To obtain these parameters, we grow epitaxial TiN(001) and TiN(111) layers under conditions resulting in large atomically-flat terraces. Partial TiN monolayers are then deposited and in-situ STM used to follow T-dependent coarsening/decay kinetics of 2D adatom and vacancy islands as well as temporal island shape fluctuations. From the results, combined with solutions of the Gibbs-Thompson and diffusion equations and a new theory of anisotropic shape fluctuations, we obtain the atomic transport parameters listed above which are then used as input into higher-level KMC and level-set models to predict microstructural and surface morphological evolution vs growth parameters.
9:10 AM	Invited	B4-3 Three-dimensional Nanostructure Fabrication by Focused-ion-beam Chemical Vapor Deposition S. Matsui (Himeji Institute of Technology, Japan) Two-dimensional nanostructure fabrication using electron-beam (EB) and focused-ion-beam (FIB) has been achieved and applied to make various nanostructure devices. Ten-nm structures are able to be formed by using a commercial available EB or FIB system with 5 -10 nm beam diameter and high-resolution resist. In this way, it is considered that the technique of two-dimensional nanostructure fabrication has been established. On the other hand, three-dimensional nanostructure fabrication has been also studied using both EB and FIB induced deposition (CVD). The deposition rate of FIB-CVD is much higher than that of EB-CVD due to factors such as the difference of mass between electron and ion. Furthermore, FIB-CVD has an advantage over EB-CVD in that it is more easily to make a complicated 3-dimensional nanostructures. Because, a smaller penetration-depth of ion compared to electron allows to make a complicated 3-dimensional nanostructures. For example, when we make a coil nanostructure with 100 nm linewidth, electrons with 10-50 keV pass the ring of coil and reach on the substrate because of large electron-range (over a few µm), so it is very difficult to make a coil nanostructure by EB-CVD. On the other hand, as ion range is less than a few ten-nm, ions stop inside the ring. This paper presents a complicated 3-dimensional nanostructure fabrication using FIB-CVD. A carbon-coil with 0.6 µm diameter and 0.08 Âµm linewidth, which was made by 30 kV Ga+ FIB with carbon containing source (phenanthrene) gas. This demonstrated that FIB-CVD is very useful to make a complicated 3-dimensional structures. Moreover, we report an evaluation of the Young modulus of such amorphous carbon pillars by measuring the resonant frequency of pillars. The spontaneous vibration of pillars was detected in SEM electron beams, and the resonant characteristics were analyzed through the signals of a secondary electron detector.
9:50 AM		B4-5 Surface Modification by Intense Ion Beams for Property Improvement of Surfaces and Thin-film Layers T.J. Renk, P.P. Provencio, S.V. Prasad (Sandia National Laboratories) This paper deals with the microstructure, friction, and wear performance of surface-alloyed and modified thin-film coatings by pulsed intense ion beams. Unlike beams used for conventional ion implantation or IBAD, the intense beams used here (nitrogen, neon, oxygen) deliver enough energy to heat and vaporize the near-surface region of a treated coating and substrate. Such a beam also can be attenuated to produce cross-linking of plastic for enhance surface hardness. Examples of surface-alloyed layers include Pt-Ti and Hf-Ti systems, which have been shown to produce significantly reduced friction with improved wear performance. The treated layers exhibited reduced grain size, and/or metastable alloy formation. Experiments are also planned to modify a surface layer for improved bio-compatibility for use in in-body implants. Studies of treated layers will be presented, including compositional measurements (EDS, RBS), and cross-sectional Transmission Electron Microscopy (TEM). The implications of ion-beam induced surface and microstructural changes on the tribological behavior will be presented. 1 Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Co., under US DOE Contract DE-AC04-94AL85000.
10:10 AM		B4-6 Tribological Properties of Nitrogen Implanted Arc-deposited PVD Hard Coatings R.J. Rodríguez, JA García (Asociación de la Industria Navarra, Spain); A. Martínez (Centre of Advanced Surface Engineering, Spain); B. Lerga, M. Rico (Asociación de la Industria Navarra, Spain); A. Medrano (Centre of Advanced Surface Engineering, Spain); G.G. Fuentes (Asociación de la Industria Navarra, Spain) In the last years, the combination of Physical Vapour Deposition (PVD) and Ion Implantation treatments has turned out to be of great interest among the industrial coating manufacturers due to the enhancements observed in the lifetime in many tested tools. In particular, high energy nitrogen ion post implantation has been reported to be an effective alternative for increasing the mechanical performance of PVD-TiN coated treated punches, dies, or moulds. This paper reports on high energy, (up to 100 keV), nitrogen ion implantation at low and medium doses on TiN, TiCN, TiAlN and CrN coatings produced by arc evaporation techniques. The chemical in-depth profiles of the implanted coatings have been measured by Glow Discharge Optical Emission Spectrometry (GDOES). The mechanical surface and tribological properties of these various hard coatings have been studied before and after nitrogen implantation. A ball-on-disk tribometer was used to characterize the coefficient of friction and the wear resistance of the nitrogen implanted coatings, whereas the changes in hardness, roughness, friction and wear coefficient were investigated and related to the implanted dose. In addition, the influence of low and medium doses of nitrogen on the tribological performance of the treated coatings, and possible new industrial applications are discussed.
10:30 AM		B4-7 Surface Nano Structuring of Titanium Thin Films Via N-implantation and Post-annealing S. Muraishi, T. Aizawa (University of Tokyo, Japan); H. Kuwahara (Research Institute for Advanced Sciences, Japan) Super saturated Ti-N thin films were prepared by combination of low temperature non-equilibrium process of ion beam sputtering deposition (IBSD) and ion implantation method. Ti thin films of 150 nm in thickness were deposited on (001) Si substrate by IBSD. N⁺ with the dose of 1x10¹⁷ ~ 2x10¹⁸ ion / cm² was penetrated into the film by ion implantation. Structural changes due to the N⁺ implantation and successive heat treatments were evaluated by XPS chemical analysis and cross-sectional TEM observation. Distribution of N in Ti film was measured by XPS and the maximum concentration of N was achieved at the Ti/Si interface with the dose energy of 100keV. Binding energy shift in proportion to N concentration was corresponded to the bonding state of TiN_x. Observed chemical shift suggested that N⁺ implanted Ti film contains finely dispersed Ti nitrides. By TEM observation, as deposited Ti film showed the conventional hcp structure with the columnar grains of 10 nm in diameter. Texture grains with the direction of [0001] α were grown perpendicular to the (001) Si substrate. N⁺ implantation made the film having the complex structure of α-Ti-N solid solution with ε-Ti₂N and TiN. Formation of Ti₂N was recognized from the TEM diffraction pattern for as-implanted specimen with 1x 10¹⁷ ion / cm² and TiN phase for 5x10¹⁷ ion / cm². Lattice constants were also measured from TEM diffraction pattern and both a and c axis of α-Ti increased as increasing the dose amounts of N⁺. Following heat treatment at 573 K and 773 K promoted the phase decomposition of nitrides and evidence of nitride formation was clearly observed from TEM diffraction.
10:50 AM		B4-8 Improvement of Ion Beam Quality for Deposition M. Kiuchi, T. Matsumoto (National Institute of Advanced Industrial Science and Technology (AIST), Japan); T. Sadahiro, K. Matsuyama, T. Takizawa, S. Sugimoto, T. Fukuda, S. Goto (Osaka University, Japan) By rejecting high energy neutrals from a low-energy ion-beam, improvement of the quality of the beam was achieved. For this, the beam system adjustment and addition of electrodes were performed. Low-energy (20-200 eV) ion-beam technique is useful for study on ion-solid interaction and deposition processes. A wide variety of deposition studies were performed, however the ion beam effects on covalent bonding materials are not clear. For producing low-energy ion-beams, a high voltage (20-30 kV) is applied for beam handling. Just before deposition, ions are decelerated to be a desired energy. The high-energy neutrals contained in the beam can not be decelerated and make damages in the depositing film. Especially, covalent bonding materials (diamond, SiC, BN, etc) are fragile by the irradiation. Thus, a discussion of high energy neutrals are essential for deposition process studies. We succeeded production of detectors for high energy neutrals. By using these, we found that the 100 eV Ar ion-beam produced by the low-energy ion-beam deposition apparatus at Osaka University contained 2% high-energy neutrals. The neutrals were considered to be produced by charge transfer with the slits and tubes in beam handling. So, we produced new beam handling electrodes and slits for adjusting the beam line. With these modification, the amount of high-energy neutrals were reduced to be 0.5%.