Fundamentals Of Ion-Material Interactions
Cambridge University Press978-1-558-99117-0 - Materials Research Society Symposium Proceedings Volume 223: LowEnergy Ion Beam and Plasma Modification of Materials: Symposium held April 30-May 2, 1991,Anaheim, California, U.S.A.Editors: James M.E. Harper, Kiyoshi Miyake, John R. McNeil and Steven M. GorbatkinExcerptMore informationPARTIFundamentals ofIon-Material Interactions in this web service Cambridge University Presswww.cambridge.org
Cambridge University Press978-1-558-99117-0 - Materials Research Society Symposium Proceedings Volume 223: LowEnergy Ion Beam and Plasma Modification of Materials: Symposium held April 30-May 2, 1991,Anaheim, California, U.S.A.Editors: James M.E. Harper, Kiyoshi Miyake, John R. McNeil and Steven M. GorbatkinExcerptMore information in this web service Cambridge University Presswww.cambridge.org
Cambridge University Press978-1-558-99117-0 - Materials Research Society Symposium Proceedings Volume 223: LowEnergy Ion Beam and Plasma Modification of Materials: Symposium held April 30-May 2, 1991,Anaheim, California, U.S.A.Editors: James M.E. Harper, Kiyoshi Miyake, John R. McNeil and Steven M. GorbatkinExcerptMore informationDYNAMIC MONTE CARLO SIMULATION OF ION BEAMAND PLASMA TECHNIQUESW.MOLLERMax-Planck-Institut fur Plasmaphysik, EURATOM-Association,W-8046 Garching, GermanyABSTRACTA multiprojectile version of TRIDYN has been employed to simulate ion-induced effects which occur during ion-beam assisted deposition (IBAD) or plasma-assisted chemicalvapour deposition (PECVD) of thin films.Simulations of the formation of boron nitride films deposited from evaporated boronand energetic nitrogen show an excellent agreement with experimental results for nitrogenconcentrations below the stoichiometric limit. For high N/B flux ratios, non-collisionalmechanisms (ion-induced outdiffusion, surface trapping of outdiffusing nitrogen) have beenincluded in the simulations, again producing good agreement with the experimental results.Simulations of the PECVD of hydrocarbon films suffer from the poor knowledgeof the neutral and ionic fluxes which contribute to the growth of the layers. Nevertheless, the composition of the films and its dependence on ion energy can be predicted withsatisfactory agreement with experimental findings.2 A simplemodel of preferential displacement yields a reasonable average ratio of sp and sp3 coordinated carbon atoms.The energy dependence of the bond ratio is in contradiction to experimental observation.INTRODUCTIONIon irradiation effects are known to play an important role for the growth andproperties of thin films being deposited by the assistance of ion beams or plasmas1"5.Although numerous phenomenological studies are available and some qualitative understanding has been achieved, the quantitative modelling of ion bombardment effects is stillat an early stage. Ions may act on a growing film physically through collisional effects likeimplantation, sputtering, atomic relocation or radiation damage. In addition, ions mightpromote chemical reactions at the surface or in the bulk, or they might enhance diffusionor precipitation. For the purpose of quantitative modelling, sufficient basic knowledge isonly available for the collisional effects. Thereby, first model calculations will apply tosystems in which mainly physical mechanisms control the growth rate and determine thefilm properties.Recently, Carter et al.6 published an analytical altered layer model for the growthof thin films under the influence of atomic relocation and sputtering. Very simplisticanalytical expressions, taking only into account the reflection of the energetic componentand the sputtering of the thermal component, have been given by Hubler and VanVechtenet al. for the IBAD of nitrides7'8. The evaluation of the analytical predictions requiresdata for, e.g., ion reflection or sputtering which are convenientlytaken from static binarycollision approximation (BCA) computer simulation9. The results of such simulationsmay alternatively be inserted into rateequations governing the layer growth. Such anapproach has been chosen by Mtiller10 in order to treat the ion-induced densification ofoxide films. As a further possibility, static BCA simulations can be11 performed stepwisewith intermediate deposition of the thermal component. Zhou et al. used this approachfor the IBAD of silicon nitride.In the most direct way, BCA computer simulation can be applied to the film growthand composition in the form of a fully dynamic simulation which covers ion and neutraldeposition, ion reflection, sputtering and atomic relocation simultaneously, thus avoidingany further simplification in addition to the restriction to collisional mechanisms. Thepresent paper will give a short description of the TRIDYN code, and show some resultsin comparison to experimental data for the IBAD of boron nitride and the PECVD ofamorphous hydrocarbon films.Mat. Res. Soc. Symp. Proc. Vol. 223. 1991 Materials Research Society in this web service Cambridge University Presswww.cambridge.org
Cambridge University Press978-1-558-99117-0 - Materials Research Society Symposium Proceedings Volume 223: LowEnergy Ion Beam and Plasma Modification of Materials: Symposium held April 30-May 2, 1991,Anaheim, California, U.S.A.Editors: James M.E. Harper, Kiyoshi Miyake, John R. McNeil and Steven M. GorbatkinExcerptMore informationCOMPUTER MODELFor the model calculationsto be described below, a modified version (4.0)12 of the13 14'hasbeenemployed. TRIDYN is based on the multicomponent,TRIDYN programmesputtering version15 of the well-known TRIM16 code. The present version treats up to fivedifferent species of incident atoms simultaneously.An extensive description of the code has been given in Ref.14. Briefly, the speciesof incident (thermal or energetic) atoms is chosen by means of a random generator according to the composition of the incident flux. In case of molecular ions, the total energy isdistributed over the atomic constituents according to their masses. The substance is subdivided into thin slabs of app. 2 A thickness. The histories of incident projectiles and knockon cascade atoms are traced as sequences of free-flight paths and elastic binary collisionsin an universal averaged screened Coulomb potential (the 'Krypton-Carbon' potential17).The inelastic energyloss to the electrons is composed with equal probability from nonlocal(Lindhard-ScharfF18) and local (Oen-Robinson19) interaction.A planar potential is adopted for the binding of surface atoms. The sputteringyields are determined critically by the choice of the surface binding energies, which aregiven below for the specific examples. The cutoff energies at which the particle historiesare terminated are set equal to the surface binding energies.The dynamic alteration of the substance is accomplished by a local relaxation ofeach depth interval according to a density given by the local composition13. The atomicvolumes of the constituents of a two-atomic substance are usually chosen in such a way thatthe densities of one pure component (e.g. boron in the case of B:N) and a stoichiometriccompound (BN) result correctly.Each incident pseudoatom in the simulation represents around 1012 projectiles/cm2.Thereby, a simulation for a total fluence of the order of 1017/cm2 requires about 105pseudoprojectiles. Typical computing times were between 1 min and 50 min on a CRAYXMP computer, depending on the ion energy.RESULTS AND DISCUSSIONIon-Beam Assisted Evaporation of B:NA thorough experimental study on the ion-assisted formation of B:N films has beenperformed by Burat et al.20. The films were prepared by simultaneous boron evaporation and No* bombardment at energies between 250 eV and 2 keV, with ion-to-neutralflux ratios between 0.3 and 2. The results include high-energy ion beam analysis of thebulk composition, Auger electron analysis of the surface composition and sputtering andincorporation measurements for nitrogen and boron.Corresponding simulation runs were performed with TRIDYN, starting with a puresilver substrate. For the surface binding energies of B and Ag, their enthalpies of sublimation (5.7 eV and 2.97 eV, respectively) were chosen. For nitrogen, the surface bindingenergy of 6.32 eV is consistent with the heat of fusion of BN and the dissociation enthalpyofN 2 .The compositional depth profile of such a simulated film is shown in Fig.l for agrown thickness of about 120 A. The interface to the silver substrate shows an intimatemixing due to nitrogen implantation and atomic mixing. For boron, a stationary bulkconcentration is not yet fully developed for the givenfluence,in contrast to nitrogen. Dueto subplantation of the energetic nitrogen behind the evaporated boron, the surface isalways enriched with boron. The simulated bulk concentrations as well as the boron andnitrogen incorporations are in excellent agreement with the experimental data for nitrogenenergies between 125 and 1000 eV/atom, as long as thebulk composition stays belowor close to the stochiometric composition of N:B 1:112. However, at N/B flux ratiosabove 1:1 the predicted nitrogen incorporation becomes excessively high compared to theexperimental findings.The good agreement between computer simulation and experiments indicates that in this web service Cambridge University Presswww.cambridge.org
Cambridge University Press978-1-558-99117-0 - Materials Research Society Symposium Proceedings Volume 223: LowEnergy Ion Beam and Plasma Modification of Materials: Symposium held April 30-May 2, 1991,Anaheim, California, U.S.A.Editors: James M.E. Harper, Kiyoshi Miyake, John R. McNeil and Steven M. GorbatkinExcerptMore information1.00Fig.l:Compositional profile of a B:Nfilm and the film/substrate interface during IBAD deposition, asobtained from a TRIDYN computer simulation. The nitrogenions are incident at an angle of30 with respect to the surfacenormal. The ion-to-neutral fluxratio is 1:1.500 eV N therm. B - Ag1.51017 (N B)/cm2N/B 1:1\\0.0040.012080.0160200Depth (A)the growth and the composition of the films with sufficiently low nitrogen concentrationcan be well described by collisional effects only. For high ion-to-neutral flux ratios whichwould result in a hyperstoichiometric nitrogen concentration, some kind of an ion-inducedoutdiffusion of excess nitrogen atoms, the detailed mechanism of which is unknown, willlimit the nitrogen concentration. This is corroborated by the finding that the nitrogensurface concentration observed in experiments with high N/B flux ratios, is larger thanpredicted by the simulation, indicating a surface nitridation by outdiffusing nitrogen atoms.In extended simulation runs, ion-induced release has been included for excess nitrogen (i.e., nitrogen above the stoichiometric concentration). From each depth intervalwithin the ion range, nitrogen atoms are removed with a rate being proportional to thelocal excess concentration. In addition, released nitrogen atoms were allowed to becometrapped at the surface with a given probability. Both the release rate and the surfacetrapping probability have been varied in order to obtain best fits to the experimental data.Fig.2 demonstrates an excellent reproduction of the experimental results when both releaseand surface trapping are included.10.0500 e V N - f therm. B8.0031017(N B)/cm0.400.8021.201.60Bulk (full symbols, upper threelines) and surface (open circles,lower lines) nitrogen density inan IBAD B:N film, for differention-to-neutral fiux ratios. Symbols represent experimental datafrom Ref.20, lines are from TRIDYN simulations with collisionalprocesses only (dotted), including local release of nitrogen abovethe stoichiometric limit with a fitted rate constant (dashed), andincluding local release and surface trapping of released nitrogenwith a probability of 0.5 (solid).N/B Flux Ratio in this web service Cambridge University Presswww.cambridge.org
Cambridge University Press978-1-558-99117-0 - Materials Research Society Symposium Proceedings Volume 223: LowEnergy Ion Beam and Plasma Modification of Materials: Symposium held April 30-May 2, 1991,Anaheim, California, U.S.A.Editors: James M.E. Harper, Kiyoshi Miyake, John R. McNeil and Steven M. GorbatkinExcerptMore information1.00Hydrogen depth profiles in C:Hfilms deposited on silicon, fromTRIDYN simulations. The filmsare modelled to grow from neutral and ionic methyl radicals withan ion-to-neutral ratio of 1:9, attwo different ion energies. Thesimulations include collisional ioninduced release of hydrogen (seetext).100200300400500Depth (A)Plasma Assisted Deposition of C:H FilmsGenerally, the modelling of ion bombardment effects during plasma assisted deposition is subject to larger uncertainties than for ion-beam assisted deposition, since theneutral and ionic species which contribute to the film growth are mostly unidentified, andtheir fluxes are generally unknown. A relatively simple system for which ion bombardment effects turn out to be significant is the plasma-enhanced deposition of C:H films fromhydrocarbon gases21 23. For a methane plasma, the CH3 radical is probably the mainspecies contributing to the layer growth (Ref.24 and references therein). A typical harda-C:H film contains about 0.4 hydrogen atoms per carbon atom. Therefore, a hydrogendepletion must occur during film growth.The TRIDYN simulation assumes that this depletion is mainly due to ion-inducedeffects. 25Experiments with a-C:H layers generated by keV hydrogen implantation intographite suggest that hydrogen can be knocked off its binding site by the interactionwith fast atoms. Subsequently, such free hydrogen atoms will recombine to moleculeswhich will quickly outdiffuse through the surface around or above room temperature. Forthe present simulations, it is assumed that the rate-controlling step is given by the knockoff.A hydrogen atom will be released after receiving an energy transfer larger than an averageC-H binding energy (2.5 eV) either through elastic energy transfer during collisions or dueto electronic interaction. Rather arbitrarily,a release efficiency of 0.5 has been assumedfor nuclear and electronic interaction24. The surface binding energies for C and H havebeen chosen as 4.5 eV, with negligible influence on the results since the sputter yields aresufficiently small.A reasonable assumption for typical RF plasma deposition conditions is a 10% ionicfraction of the impinging hydrocarbon flux24. CHjJ" is chosen as a model ion for the simulations. A typical result is shown in Fig.3 for two different ion energies. Significant interfacemixing is only observed for the higher ion energy of 400 eV, being 26in good quantitativeagreement with experimental results obtained from sputter profiling . The bulk concentration of hydrogen is also in good agreement with experimental experience. At an ionenergy of 400 eV, an atomic ratio of about 35% is predicted which is typical for a harda-C:H film, whereas a low energy results in a polymer-like film with a high hydrogen concentration. However, these results should be considered merely qualitatively in view of theabove assumptions and simplifications. The simulation also predicts hydrogen enrichmentat the surface, which has also been confirmed experimentally27.The optical, mechanical and electrical properties of C:H films are determined bothby their hydrogen content and their bonding structure. The filmsare considered to mainlyconsist of an amorphous networkof graphitic islands with sp2 bondswhich are intercon3nected by diamond-like sp bonds. For the formation of either sp2 or sp3 bondsduringfilm growth, a preferential displacement model has been2 proposed qualitatively28"30 whichaccounts for the different displacement thresholds of sp coordinated carbon atoms (25 eV in this web service Cambridge University Presswww.cambridge.org
Cambridge University Press978-1-558-99117-0 - Materials Research Society Symposium Proceedings Volume 223: LowEnergy Ion Beam and Plasma Modification of Materials: Symposium held April 30-May 2, 1991,Anaheim, California, U.S.A.Editors: James M.E. Harper, Kiyoshi Miyake, John R. McNeil and Steven M. GorbatkinExcerptMore information6.5Fig.4:Ratio of diamond-like and graphite likecarbon bonds in mass-selected ion beamor plasma-deposited C:H Elms versusion energy, for different ionic and neutral species. Lines are from TRIDYNsimulations including a simple preferential displacement model (see text).Experimental data, are shown for comparison, which have been obtained frominfrared absorption after methane plasmadeposition (Ref.31, full points, abscissadenotes self-bias voltage), and from nuclear magnetic resonance after acetylene plasma deposition (Ref.32, opencircles, abscissa denotes measured meanion energies).5.2 3.9o2.61.3 -10z LIon Energy (eV)in graphite) and sp3 carbon (80 eV in diamond). TRIDYN simulations have been performed in order to quantify this proposal. It is assumed that carbon atoms are releasedfrom their sites at elastic energy transfers above their displacement thresholds. Both implanted and released atoms are fed into the sp2 or sp3 populations with equal probability.Results are shown in Fig.4 for different species which impinge during mass-selectedion beam deposition or plasma deposition, together with some experimental data 31 ' 32 . Arather good agreement between experiment and model prediction is observed for the average bond ratio in the present range of ion energies. However, discrepancies are found for theenergy dependence: Whereas the predicted bond ratio steadily increases at increasing ionenergy, the experiments reveal a decrease towards high energy. (It should be noted that theresults of Refs. 31 and 32 are not necessarily in contradiction, as infrared absorption31 onlyprobes hydrogenated carbon atoms.) A clear increase of sp2 bonds at high energy is alsoconfirmed by recent detailed NMR studies performed after methane plasma deposition33.From this, one may conclude that the present simple model of preferential displacementalone is not sufficient to describe the bond ratio in amorphous hydrogenated carbon films.CONCLUSIONSIt has been demonstrated in the present paper that dynamic computer simulationsbased on the binary collision approximation may be of great help for the understandingof ion bombardment effects during thin film growth. The existence of systems whichare mainly governed by collisional effects has been proven. It is also possible to includea simple modelling of other than collisional mechanisms such as ion-induced release oratomic trapping.Especially for plasma deposition, the capability of the simulations is hampered bythe poor knowledge of the boundary conditions such as ion and neutral fluxes and energies.It is desirable that the availability of simulations of the present type would trigger anincreased activity in performing well-characterized experiments correlating the impingingspecies and the properties of the resulting films. in this web service Cambridge University Presswww.cambridge.org
Cambridge University Press978-1-558-99117-0 - Materials Research Society Symposium Proceedings Volume 223: LowEnergy Ion Beam and Plasma Modification of Materials: Symposium held April 30-May 2, 1991,Anaheim, California, U.S.A.Editors: James M.E. Harper, Kiyoshi Miyake, John R. McNeil and Steven M. GorbatkinExcerptMore informationREFERENCES1. J.M.E.Harper, in Plasma Surface Interactions and Processing of Materials, edited byO.Auciello, A.Gras-Marti, J.A.Valles-Abarca, and D.L.Flamm, NATO ASI Series E,Vol.176 (Kluwer Academic Publishers, Dordrecht, 1990), p.251;J.E.Greene, S.A.Barnett, J.-E.Sundgren, and A.Rockett, ibid., p.281.2. D.M.Mattox, J.Vac.Sci.Technol.A 7,1105(1989).3. S.M.Rossnagel and J.J.Cuomo, Thin Sol.Films 171,143(1989).4. G.K.Wolf, Nucl.Instrum.Meth.B 46,369(1990).5. H.Oechsner, Thin Sol.Films 175,119(1989).6. G.Carter, I.V.Katardjiev, and M.J.Nobes, Vacuum 39,571(1989).7. D.VanVechten, G.K.Hubler
Fundamentals of Ion-Material Interactions . (Oen-Robinson19) interaction. A planar potential is adopted for the binding of surface atoms. The sputtering yields are determined critically by the choice of the surface binding energies, which are . 30 with respect to the surface normal. The ion-to-neutral flux
polyatomic ions: a. amm onium ion b. sulfate ion c. sulfite ion d. carbonate ion e. nitrate ion f. permanganate ion g. hypochlorite ion h. phosphate ion i. cyanide ion j. hydroxide ion 9.2 Naming and Writing Formulas for Ionic Compounds A. _ Ionic Compounds 1. What are Binary Ionic Compounds? 2.
ION 7550 / ION 7650 User Guide The ION meter in an Enterprise Energy Management System Chapter 1 - Introduction Page 11 The ION meter in an Enterprise Energy Management System You can use ION 7550 and ION 7650 meters as standalone devices, but their extensive capabilities are full y realized when used with ION software as part of an
Table 3 Additional Ion kits used with the Ion 16S Metagenomics Kit Description Cat. no.[1] Quantity Ion Plus Fragment Library Kit 4471252 1 kit Ion Xpress Barcode Adapters 1-16 Kit[2] 4471250 1 kit Ion PGM Hi‑Q OT2 Kit A27739 1 kit Ion PGM Enrichment Beads 4478525 1 kit Ion PGM Hi‑Q Sequencing Kit (use with Ion PGM .
User Management: System administrators can create/edit/delete users and define . ION 7550 1,2,3,4 YES YES YES ION 7600 1,2,3,4 YES YES YES Schneider Electric ION 7650 1,2,3,4 YES YES YES ION 7700 1,2,3,4 YES YES YES ION 7750 1,2,3,4 YES YES YES ION 8300 1,2,3,4 YES YES YES ION 8400 1,2,3,4 YES YES YES ION 8500 1,2,3,4 YES YES YES .
Ion GeneStudio S5 System - Cat. No. A38194 OR Ion GeneStudio S5 Plus System - Cat. No. A38195 OR Ion GeneStudio S5 Prime System - Cat. No. A38196 Ion 510 Chip Kit - Cat. No. A34292 (8 chips) Ion 520 Chip Kit - Cat. No. A27762 (8 chips) Ion 530 Chip Kit - Cat. No. A27764 (8 chips) Ion 540 Chip Kit - Cat. No. A27765 (4 chips) or
GeneStudio S5 System, Ion GeneStudio S5 Plus System, or Ion GeneStudio S5 Prime System. An external Ion Torrent Server is required for use with the Ion GeneStudio S5 Prime Sequencer and is included in the Ion GeneStudio S5 Prime System. Note: In this guide, Ion GeneStudio S5 Sequencer or System refers generically to the series .
1 1 Lecture 9 Ion – surface interactions References: 1) L.C. Feldman, J.W. Mayer (1986) Fundamentals of Surface and Thin Film Analysis. 2) Y. Wang, M. Nastasi (2010, or previous edition) Handbook of Modern Ion Beam Materials Analysis.
(OSH Act) standards because they were rarely exposed to construction jobsite hazards. However, with the increasing roles that designers are playing on worksites, such as being part of a design-build team, it is becoming increasingly important that they receive construction safety training, including information about federal and state construction safety standards. The Occupational Safety .
