Fundamental aspects of direct ion beam deposition (IBD) are discussed, stressing surface preparation and contamination problems. Residual gas contamination, ion beam induced metal contamination, and presence of surface native oxide before deposition are shown to be the major factors hindering low temperature epitaxial growth in IBD. A low energy hydrogen ion bombardment is demonstrated as an effective surface preparation method to remove surface native oxide in the case of silicon deposition.

The ion beam assisted deposition (IBAD) technique has been employed to make aluminum oxide optical coatings. Deposition variables include aluminum oxide evaporant to oxygen ion beam flux ratios, substrate temperature, and ion energy. Characterization included optical ellipsometry, ion beam analysis, and adhesion tests. Films deposited with the aid of ions exhibited the highest refractive indices and best adhesion to their substrates.

A series of experiments have been performed to examine the ability of ion beam assisted thermal deposition to produce good adhesion of Au metallization on GaAs <100> substrates. A study of the influence of Ar ion-assisted thermal deposition of the Au films as well as in situ pre-sputtering of the GaAs surface with low-energy Ar ions prior to thermal deposition, shows that strong adhesion can be achieved without resorting to chemical cleaning. The substrate temperature and the relative flux of Ar ions to incident Au atoms were varied in order to correlate these parameters with film adhesion. The interfaces of films processed under these various conditions were examined by XTEM, RBS and XPS. Orientation texture was studied by x-ray diffraction (XRD).

SiO2 films were prepared at a substrate temperature of 100°C by the simultaneous use of a microwave ion source and an ICB system. Transparent and good insulating SiO2 films could be obtained by using 02 gas ions, and they were thermally and chemically stable. Furthermore, both the ionization energy and the incident energy of the 02 gas ions were found to enhance the chemical reaction between SiO and 02 molecules, resulting in the Si02 film formation at a low substrate temperature.

A new approach to modeling the evolution of islands in thin films by growth and coarsening during ion bombardment is described. Solution of a continuity equation and matter conservation relation, coupled with interface-limited and diffusion-limited rate laws for island growth and coarsening allows the kinetics of island evolution to be modeled. Results from the model indicate distinct kinetic paths for island evolution during ion bombardment as a result of growth, enhanced diffusion, island dissociation and monomer sputtering.

RF sputter deposition of 500 nm thick zirconium films was carried on simultaneously with implantation of singly ionized molecular nitrogen. Samples were prepared at room temperature (23°C) with a nitrogen to zirconium arrival ratio varying from 2.7x10-2 to 4.4x10-1 and with the ion energy varying from 100 to 300 keV.

Stoichiometry of the films and ion concentration profiles were determined by Rutherford Backscattering Spectrometry. Results from a theoretical model for the ion concentration profiles were compared to profiles derived from experiments. Grazing Angle X-Ray Diffraction was used to correlate nitride phase formation to processing parameters.

Knoop microhardnesses of films deposited on 304 stainless steel substrates were determined. The relative microhardness of the samples were studied as a function of parameters such as film stoichiometry and ion implantation energy.

The microstructure of tungsten films deposited by ion-assisted evaporation (IAE) has been examined by transmission electron microscopy. It is proposed that grain shape is strongly associated with stress and texture changes in IAE films. Evidence is also found of stress induced damage in the substrate due to stress transfer from the deposited tungsten films.

Polyimide thin films are deposited by the ionized cluster beam deposition( ICBD ) technique. Polymerization and crystallization of polyimide were investigated using TEN, IR, and the electronic structure of the polyimide film was investigated using XPS. Films deposited at optimum ion acceleration voltage showed strong preferential crystal orientation. Crystalline polyimide film was obtained at ion acceleration voltage of 700 V.

In ion-assisted deposition techniques such as partially ionized beam deposition, ions derived from the depositing material itself concurrently bombard the surface during thin film growth. The ion percentage in the deposition beam ranges from less than 0.1% to 100% (Ion Beam Deposition) with the ion energy varying between a few eV and several keV. When the sputtering yield of the self-sputtering is greater than one, there is a critical ion percentage, for a given ion energy, above which no net deposition can be obtained. The self-sputtering yield is shown to have a square root dependence on the ion energy above the threshold energy by fitting the experimental data obtained from the literature. The critical ion percentage for Al, Cu, Au, Ag, and C is then calculated and plotted as a function of the ion energy so that deposition and no-deposition regions are illustrated in terms of the ion energy and ion percentage.

The annealing behavior of the optical properties of boron nitride films (BxN1-x) is described for films fabricated by ion beam assisted deposition. The data are needed for the precise manufacture of optical filters, where the index of refraction must be predicted from deposition parameters and film annealing history.

The reflection of homogeneous samples deposited at room temperature on (100) silicon substrates was measured from 400 to 3125 nm. to obtain the wavelength dependence of the index of refraction as a function of film nitrogen content. Nitrogen atom fraction was varied from 0.325 to 0.5 by variation of the incident of nitrogen ion beam current to evaporant boron flux ratio. The films were annealed in argon at 500 C and 700 C, and the optical measurements repeated after each anneal. The index of refraction obtained for the annealed films was used to design a narrow band optical reflection filter at 1060 nm. The filter, constructed by sinusoidally varying the index of refraction of the BxN1-x film by varying ‘x’, performed as designed.

Electron-beam evaporated nickel was deposited onto sapphire or rocksalt substrates at room temperature with and without simultaneous argon ion bombardment. The ion energies were 100, 500, or 1500 eV, with ion-to-atom arrival ratios, R, ranging from 0.01 to 0.1. For each film, the microstructure, density, resistivity, and amount of retained argon was measured. It was determined that 100 eV bombardment produced an increase in density with little change in resistivity, whereas 1500 eV bombardment decreased the density and increased the resistivity monotonically with R. The reduction in density was correlated with decreasing microstructural feature size and decreased preferred orientation which suggested that the ions induced an increase in the volume fraction of boundaries.

Boron nitride and titanium-boron multilayers (some of which were implanted with nitrogen- or argon ions) have been deposited on pure titanium substrates with an RF sputtering technique. The high temperature (850 °C) behavior of these samples in an oxidizing atmosphere has been studied. While the boron nitride coatings decompose rapidly, with boron diffusing to the surface, an important role for nitrogen has been evidenced. The concentration of nitrogen found at the interface, forming a diffusion barrier, can account for a certain degree of protection.

(111) PbTe // (111) BaF2 epilayers have been prepared by rf magnetron sputtering. A small negative substrate bias voltage (-10 V) enhances the (111) growth habit at reduced substrate temperatures (180 °C) and increased deposition rates (2.5 μ/h–1). Langmuir probe diagnostics is used to determine the energy and flux density of Ar ions incident on the growing film. Hall effect measurements are made to determine the carrier type and mobility as a function of the growth temperature.

Silver films were deposited on alumina substrates using ion bombardment. Adhesion strength was measured as a function of deposition conditions, sputter-cleaning time, and bombarding ion species, using a pull-type adhesion tester. Argon- and argon/oxygen-ion sputtering produced large increases in adhesion strength, with the greatest increases occurring for oxygen-ion bombardment. Adhesion strength increased monotonically as a function of ion sputtering time. At a given deposition rate, further enhancement of adhesion is seen with concurrent ion bombardment.

A Monte-Carlo computer simulation has been performed to describe, at atomic level, the growth of titanium nitride films formed by ion beam enhanced deposition (IBED). The simulation is based on a random target, fixed free path of moving particles and binary collisions. An alternate process of deposition of titanium atoms and implantation of nitrogen ions is applied instead of the actual continuous and synchronous process of IBED. According to the actual conditions, the adsorption of nitrogen gas, which is leaked out from the ion source, at the fresh titanium layer surface has been considered. In addition, the change of the composition profile and the density profile during film growth is taken into account. It is demonstrated that the width of the intermixed region between the film and substrate increases with the increase of the atomic arrival ratio, R, of implanted nitrogen ions to deposited titanium atoms. When the titanium deposition rate is low, the nitrogen concentration of the film is relatively insensitive to R, indicating that a dominant contribution to the nitrogen concentration is derived from the nitrogen gas leaked out from the ion source. The results obtained in this study are in agreement with the experimental measurements.

Existing theories of irradiation-induced grain growth assume that growth occurs by the boundary migration mechanism commonly observed for thermal growth and that it is only the point defects generated si boundaries during the irradiation which are responsible for boundary migration. In contrast, in situ observations during ion irradiation of Au films at temperatures less than 20 K even have clearly demonstrated that growth occurs both by boundary migration and by grain coalescence. Here we present further evidence for the latter. Furthermore, the substantial defect cluster activity observed during irradiation suggests that dislocations play a significant role in the growth phenomenon. Here, we also demonstrate qualitatively that glide of such dislocations to or “through” a boundary can produce essentially the same effect on boundary position or structure that the original point defects would have had if they had migrated individually to or through the boundary. Via dislocation motion, point defects originating far from a boundary may induce boundary migration or boundary structure change, and hence, grain growth.

Amorphous GexSi1–x layers are shown to crystallize epitaxially from an underlying (100) oriented Si substrate when irradiated with 1.5 MeV Ne ions at temperatures as a low as 275°C. For a given Ne fluence, the extent of crystallization is shown to increase with increasing Ge content, consistent with the increased defect production rate in these alloys. It has also been demonstrated that strained layer configurations can be grown by ion-beam annealing and that such layers exhibit a commensurate to incommensurate transformation within the same composition range as layers grown by molecular beam epitaxy.

The interface velocity of Au and Ag doped amorphous Si during ion beam induced epitaxy was measured using in situ time resolved reflectivity. Interfacial segregation coefficients were determined as a function of composition from numerical simulations. At 320°C Au impurities enhanced the velocity by up to a factor of 2.5 compared to the intrinsic case. Silver slightly retarded re-growth by 10 %. These effects are qualitatively similar to the case of thermal solid phase epitaxy. Using the measured impurity profiles and interface velocity, computer simulations relate the segregation coefficient to the concentrations of the impurity at the interface. In both cases, the segregation coefficient increases with increasing interfacial impurity concentration.

Ion beai induced epitaxial crystallization (IBIEC) in preaiorphized BP(100) has been investigated by RBS channeling experiients. Re-crystallization was induced by subsequent ion boibardients with 400 keV Kr, 400 keV Ar and 800 keV Ar at temperature range between 200°C and 450°C. The current densities of Kr and Ar ions were selected to give the saie energy deposition rate in the elastic collision process. Epitaxial crytallization was observed at teiperatures luch below those required for the therial solid phase epitaxy (SPE) process (above 800°C). The critical temperature for crystallization at typical current densities was 230°C. The ion species used for the preaiorphization give a weak influence on the regrowth rate. On the scale of deposited energy density in the elastic collisions, ion boibardients with higher electronic excitation efficiency were found to be effective in the regrowth process. Dose rate is found to be of iiportance in the regrowth process. The activation energy observed in Ar ion boibardients was 0.18±0.05 eV.

The ion beam induced growth of isolated silicon grains has been studied in chemical vapor deposited amorphous layers. The crystal radius increases linearly with the 1on dose and the growth rate depends in a complex way on the irradiation temperature in the 320 - 480 °C investigated temperature range. The grain density does not depend on the ion dose but it increases exponentially with increasing irradiation temperature. The grain density obtained after a pure thermal process on similar samples is In any case larger than the density appearing after ion irradiation. These facts may be explained by assuming that during ion irradiation only pre-existing seeds whose size is larger than a critical value can grow. This critical cluster size is larger than the critical cluster size for a pure thermal process.