Enhanced adhesion of a film of non-reactive metal deposited on a ceramic or glass substrate can be produced by irradiating the interface with an ion beam. The resulting bond can be improved by subsequent heat treatment. The interface remains abrupt. The mechanism of this bonding is discussed, and the effects of interface contaminants are examined for the Cu-Al2O3 and Au-Al2O3 systems. Finally it is noted that strong adhesion is produced when Al2O3 is subjected to preferential sputtering at the time of Cu deposition; the resulting interface chemistry is discussed.

The diffusion processes in thin films are largely controlled by their microstructure and chemistry. In this publication, we discuss briefly how the recently devel-oped experimental techniques coupled with the available analytical treatments have been able to characterize these processes. Actually a hierarchy of diffusion rates along the atomic defects in thin films, namely the vacancies, grain-boundaries and dislocations, has been found. The interactions of solutes present in thin films with the atomic defects in altering the diffusion rates are discussed. It has also been possible to measure diffusion in amorphous metallic alloy films and its features are described. Finally, we outline the general principles for modifying diffusion in thin films to achieve the desired technological objectives.

There is a great deal of interest in forming Au grains on semiconductor and insulating substratcs for device application. Reduction in density of grain boundaries is known to cause improvement of clectromigration in thin films. Transmission electron microscopy and diffraction have been used to study the growth behavior and morphology of vapor deposited Au on these substrates. Electron beam evaporation techniques were used to evaporate Au at high rates (50Å/sec or higher) on substrates held at low temperature (Rm. Temp. to 250°C). Large Au grains laave been found to form on both amorphous (Si3N4 and SiO2) and single crystal Si substrates. The grain size of Au was also found to be dependent on substrate surface roughness; rough surfaces tended to retard the formation of large grains. Grains as large as 1/2 μ in a matrix of smaller ones were observed in films as thin as 350Å Annealing up to 350°C, subsequent to deposition, did not appreciably increase the size of the larger grains, although the smaller ones grew by about 10%. The TEM analysis together with RBS and AES data showed no significant interaction between Au and Si (that is to say no atomic intermixing or silicide formation) under all deposition conditions as well as annealing heat treatments. The significance of this in relation to the growth behavior of Au on the insulating and single crystal Si substrates will be shown.

Secondary grain growth in thin Au films on SiO2 substrates with periodic surface relief structures was studied as a model for the application of graphoepitaxy (the growth of orientated crystalline films through the use of artificial surface patterning). Secondary grain growth driven by sur-face energy anisotropy produces grains many times larger than the film thickness with uniform texture. In thin films of Au on SiO2, surface-energy- driven secondary grain growth was found to occur at room temperature as soon as the film becomes continuous, and was shown to be responsible for the {111} deposition texture. A square-wave-profile grating of 0.2 μm period, etched into the surface of the substrate, resulted in preferred growth of {111}-textured grains with <112> directions oriented parallel to the grating axis. It is proposed that surface energy minimization is responsible for this phenomenon.

The goal in this study was to investigate the effect of the impact velocity of the atoms on the structure of thin films generated by vacuum deposition. For that purpose all atoms faster or slower than a pre-selected velocity, u, were removed with a velocity filter frm a beam of gold atoms obtained by thermal evaporation in vacuum (10−5 Pa). The residual atoms (with a velocity u)were deposited onto cold (80 K) glass substrates. The annealing behaviour of the films studied by means of d.c. resistance measurements indicates a correlation between film structure and impact velocity in the sense that films generated by means of low velocity atoms have a non-equilibrium structure which does not exist in films prepared by conventional vacuum deposition.

We present results for the electronic structure and chemical properties of thin Pd films grown epitaxially on Au(lll) single-crystal substrates. Photoemission spectroscopy is used to monitor the development of the Pd d-bands near the Fermi energy (EF ) as a function of overlayer thickness. The state density aF E is relatively small for the single Pd monolayer (ML), but increases monotonically with overlayer thickness, resembling the bulk Pd electronic structure for films thicker than 5 ML. At the same time we observe that the 1 ML Pd film is iner with respect to CO chemisorption, while the multilayer films readily chemisorb CO, similar to bulk Pd. We examine possible models for the inert behavior of the Pd monolayer, based on related slab calculations which show the substrate-induced modification of the electronic structure in the overlayer.

Thin films can break up into islands only if they are perturbed by substrate-intersecting perturbations. Grain boundary grooves and vertex pits are typical defects which nucleate holes in these films. Holes which exceed a critical size - proportional to the ratio of the film thickness to the equilibrium contact angle - grow, eventually disconnecting the film.

X-ray diffraction, chemical etching and electron microscopy are useful in delineating the microstructural properties of c-axis normal oriented polycrystalline zinc oxide films, sputter deposited on amorphous substrates. Dense ZnO films with high crystalline content and low etch rates have a strong piezoelectric effect and low surface acoustic wave and guided optical wave propagation loss. The structural properties are dependent upon substrate conditions, deposition parameters and the type of sputtering system used. Scanning electron microscope examination of the surface and side fractures of high quality ZnO films show smooth continuous upper surface and side regions with no vertical fiber grain structures apparent. Light chemical etching reveals surface defects consisting of uniformly distributed conical shaped etch pit structures with a lateral to vertical etch ratio of 3 to 1. A correlation has been made between film structure and single crystal zinc oxide. The structural picture which emerges is that of a predominantly positive polarity (0001) upper surface layer with localized negative polarity (0001) fiber grain inversions. The sputter conditions which lead to low defect density films are a high substrate temperature, high deposition rate and low reactive gas pressures to promote the adatom mobility necessary for the preferred (0001) zinc face growth. Post deposition laser and thermal annealing can be used to reduce stress in the films and improve their guided optical wave properties.

Films which are nominally aluminum nitride were grown by reactive sputter deposition using an aluminum target and rf-excited nitrogen discharges operated at power levels from 100 to 800W. Depositions were made on water-cooled (111)-cut Si and amorphous quartz substrates. The optical behavior of these films and its relationship to chemistry is discussed in the present paper.

The effects of ion bombardment during film deposition on surface and volume microstructure were studied. Both metal and dielectric films were investigated. Scattered light and optical constants were examined for evaporated, sputtered and ion assisted films.

Epitaxial relations in Cax Sr1−xF2(0⫶×⫶l) and BaF2 films grown on GaAs(111), (111) and Ge(111) substrates were investigated by He ion channeling analysis and transmission electron microscopy. Though the lattice constants of GaAs and Ge are nearly the same, the relations were found to be completely different. That is, the fluoride films on GaAs prefered to have an orientation identical to that of the substrate (type A orientation), whereas the orientation of the films on Ge was mainly rotated by 180° about the surface normal 〈111〉 axis (type B orientation). A hypothesis is proposed that the epitaxial relations in these systems are affected by the ionicity of the substrate as well as the lattice matching condition.

A constant alternating current stressing technique is employed to study the electron trapping and detrapping cha~acteristics within a layer of thin silicon dioxide (˜.100 Å). A two-charge centroid model is proposed to explain the trapping/detrapping phenomena under high electric fields. The oxide breakdown mechanism induced by the local field of trapped electrons is also discussed.

Optical coatings may be deposited from clear polymeric solutions derived from metal-organic compounds. These coatings are converted to their oxide counterparts upon heating at temperatures of 400–500°C. In this work, the surface roughness of solution deposited SiO2 films were investigated in order to assess their suitability for such applications as waveguides, mirrors, etc.

SiO2 films deposited from polymeric siloxane solutions show rms surface roughness as low as 2.2Å in profile scans extending over 600 μm. The surface roughness of these films, as well as other properties, are found to be modified by the deposition method, e.g., spin or dip coating, as well as by the reaction parameters involved in the solution preparation.

The crystallization behavior of amorphous Mo-Ge alloys in the Ge-rich region have been characterized by resistivity measurements and transmission electron microscopy (TEM). Alloys with compositions in the metalsemiconductor transition region, where two distinct types of SRO occur, show compositional segregation on a fine scale during the first transformation step. Alloys in the adjacent composition region, where SRO is similar to the intermetallic compounds, crystallize polymorphically into metastable structures based on the equilibrium intermetallic structures. The resistivity characteristics and the relationship between the amorphous and partially transformed structures are discussed.

Stress measurement in thin film systems is discussed and applied to Al-2%Cu filns on SiO2/Si substrates during thermal cycling. Plastic deformation obscrved during compressive stress relaxation is correlated with the formation of hillocks on the metal films. The effect of secondary layers of 10%Ti-90%W on the thermo-mcchanical response of Al films is examined.

The recent development of a more systematic, scientific basis for knowledge in electrodeposition technology is discussed, focussing on the influence of microstructure on deposit properties. Internal stresses, tensile strength, ductility, preferred orientation and the ability to electrodeposit amorphous materials are considered. In particular the unique influence on these properties of small quantities of chemical additives is discussed. The application of current modulation techniques during electrodeposition is described as an alternative means of controlling structure and properties.

Amorphous metal alloy films have been produced using a new technique. Nominally NiP alloys are made by dissociating mixtures of nickel carbonyl and phosphine using a radio-frequency discharge in either an argon or a hydrogen carrier gas. This process incorporates significant amounts of carbon and oxygen impurities into the film. A previously unreported relationship between the interatomic bonding involving these impurities and the electronic transport properties of the films is discussed in this paper. The bonding studies were carried out principally using Auger lineshape analysis. Transport properties measured included 4-terminal resistivities, Hall mobilities and carrier concentrations, and Seebeck coefficients. Covalent bonding of Ni with C or P with O is strongly correlated with high resistivity, mainly through a decrease in carrier density.

The drive to produce smaller devices in integrated circuits is wellknown. Concurrent with this drive is the need to incorporate new materials, such as silicides, as interconnects, diffusion barriers, and contacts. During circuit fabrication, these materials are in contact with other solids and gases at elevated temperatures. Consequently, reactions may occur which degrade the materials present. Since the reactions of interest typically involve three elements distributed in several phases, ternary phase diagrams are required to predict the occurrence of a reaction and the subsequent reaction products, or, conversely, the stability of the phases present. Hence, ternary diagrams can provide important guidance in the selection of optimal materials and the design of reliable processing schedules.

Little is known about the development of film stresses in very thin films (thicknesses of the order of a few hundred Angstroms or less). As interest intensifies in the technological application of ever smaller quantities of materials, the behavior of very thin. films will undergo increasing scrutiny. In this study, the film stresses in evaporated Pd films and Pd2Si films formed by reaction with the Si substrates at 250°C were measured for thicknesses ranging from 7 to 107 nm. Stresses were calculated from the substrate radii of curvature determined by X-ray diffraction topography techniques (Lang and double crystal) and Stoney's equation. Because film continuity cannot be taken for granted at low coverage, the films were examined by electron microscopy in an attempt to correlate their morphology with the observed stresses.

In this study, we survey germanide formation and characterize Schottky- barrier properties for a number of representative metals on Ge (Al, Ag, Au, Er, Ni, Pd, Pt, Ta and Ti). It is found that the germanide formation characteristics (sequence of phase formation, kinetics, moving species) are similar to those of the corresponding silicides. The Schottky-barrier heights, however, are all similar and centered around 0.59 eV arida re relatively insensitive to the metallization.