A clear understanding of the bonding process in the cofired tungsten-aluminum nitride (W-AIN) metallized system is not currently available. Therefore, in an attempt to obtain a fuller understanding of this process, reactions between metallic W, tungsten trioxide (WO3), and calcium tungstate (CaWO4) with aluminum nitride have been studied using a variety of electron microscopy techniques. The observed reaction was found to be similar in all cases, resulting in the formation of metallic tungsten particles within the AIN substrates. A reaction sequence is proposed to explain adhesion in the W-AIN metallized system; thermodynamic calculations support the proposed reaction sequence. The adhesion in this system is due to both a mechanical fastening by an interlocking and a chemical precipitation reaction. Finally thermal conductivity measurements across the interface have been made to assess the ability of the interface to transfer heat.

The load dependence of interracial failure induced by microindentation has been studied. It is demonstrated experimentally that substrate lateral defects induced by indentation contribute significantly to interracial failure. The microhardness of translucent AIN was measured at temperatures up to 1200°C. The hardness decreased from 10.6GPa at room temperature to 4.0GPa at 1200°C.

Decomposition of a palladium compound by ion irradiation has been used to catalyze electroless plating on polyimide. First, palladium-acetylacetonate or -acetate is spin-coated on a polyimide substrate. The thin resist film is then irradiated through a mask with He or Ar ions of 100 keV energy. After washing off the film parts which were not exposed to the ion beam, copper is deposited on the catalyzed polyimide substrate in an alkaline electroless plating bath. When using alkaline resistant polyimide, copper lines several microns thick can be plated. The chemical surface composition of the Pd-compounds after ion beam exposure has been investigated with ESCA. It has been found that the Pd is partially reduced. Pd-acetate is more effective to form catalytic sites than Pd-acetylacetonate.

A real-time x-ray analysis technique has been developed and employed for in-situ investigation of solid and liquid state reactions in Au-Sn/Cu system as a function of temperature. Typically, 1 μm eutectic Au-Sn films were deposited on 1.5 μm Cu layers on Si wafers. Phase changes in Au-Sn films on Cu from ambient to above the eutectic temperature have been investigated. Cu diffusion into Au-Sn film above 250 °C resulted in a ternary Au-Sn-Cu compound and raised the melting temperature of the structure to about 325 °C. This affects joining characteristics of the Au-Sn metallization.

A detailed study of the interdiffusion and resistivity of Cu/Au, Cu/Co/ Co/Au and Cu/Co/Au thin film structures was carried out at temperatures ranging from 25 to 550°C1. Both Cu and Au, in the Cu/Au structure, intermix readily even at temperatures as low as 150°C and the interdiffusion is accompanied by rapid increase in resistivity. Very little interdiffusion occurs in the Cu/Co, Co/Au or Cu/Co/Au thin film structures up to about 400°C, after which the resistivity increases. The very rapid increase in resistivity observed at 250°C for the Cu/Au system and at 450°C for Cu/Co/Au, is associated with recrystallization of the films into large grains and the formation of AuCu, Cu3Au and Cu3Au2 compounds. The Cu/Co/Au structure recrystallizes at a higher temperature because of the time needed for Cu and Au to diffuse through the Co layer, which did not react significantly with either Au or Cu.

Contact reactions at thin film Al/TM interfaces (TM = W, Cr, Co, Zr and Ta) have been studied by means of cross sectional transmission electron microscopy. In all cases the first phase formed at the interface was the most aluminium-rich compound as given in the correspondent phase diagram: In the case of Al/W, Al/Cr as well as Al/Co growth of Al12W, Al7Cr, and Al9Co2, respectively, with rather smooth, planar morphology has been observed. On the other hand, Al/Zr and Al/Ta contacts exhibit a irregular growth morphology of Al3Zr, and Al3Ta, respectively.

In addition, precipitation behaviour of rapidly solidified supersaturated Al(TM) solid solutions upon thermal annealing has been studied, in order to get a better insight on preferred orientation relationships between aluminium and the aluminides as well as on the influence of defects, e.g. grain boundaries.

Based on the observed morphologies and orientation relationships a model will be proposed for the different modes of interfacial reactions, i.e. with planar or irregular growth morphology.

The events associated with fractures along interfaces between copper thin films and glass substrates were investigated by X-ray diffraction and transmission electron microscopy (TEM). In the as-bonded films the Bragg diffraction lines were shifted and broadened (relative to pure strain-free copper) due to residual in-plane tensile strains arising from the differences in thermal contraction between the copper and the substrates; TEM studies of these films in cross-section showed that the residual stresses had been relieved somewhat by dislocation densities as high as 1010 lines/cm2 in Cu/SiO2 films.

The passage of a crack along the Cu/glass interfaces led to a significant reduction in the line shift and a slight reduction in the line broadening. Thus dislocations generated by the fracture events ‘plastically relaxed’ the residual stresses present in the as-bonded Cu by superposing a compressive component onto the pre-existing in-plane tensile strains. This dislocation generation was confirmed by TEM studies. In addition, it was found that the greater the strength of an interface, the greater was the reduction in mean strain due to the fracture; this is consistent with a larger crack-tip plastic zone and the generation of greater numbers of dislocations in the Cu films by fracture along interfaces of higher toughness (i.e. bond strength).

We studied the reactivity of titanium with the R-plane (112) surface of sapphire by transmission electron microscopy (TEM), x-ray diffraction (XRD), and Rutherford backscattering (RBS) techniques. Cross-section TEM specimens were prepared from 200–400 nm thick titanium films deposited on sapphire at 25, 525, 554, 562, 580, 630, and 663°C to observe the interfacial region. In samples deposited at 25°C, without further annealing, no reaction zone could be seen in the TEM. In all other samples titanium reduced the sapphire to form Ti0 6 7[O0 3 3] and Ti3Al[O], Ti and Ti3Al with oxygen in solid solution. An activation energy of 24.7 ± 6 kcal/deg-mole was determined for the growth of the Ti3Al[O] layer. Layer thickness measurements from the TEM and RBS studies were within 10–20% of one another.

Evolution of the fractional change of electrical resistance ΔR/R in thin films of Au on (001) substrates of semi-insulating GaAs has been investigated as a function of time t, temperature T, and current density j. Initially, ΔR/R increases linearly with increasing t for constant T and j, and exponentially with increasing T for constant t and j, characterized by an activation energy of 0.73 eV. An analytical model is developed to evaluate ΔR/R for the early stages of electromigration. This model is based on flux divergence at grain boundary triple junctions resulting from variations of grain boundary inclination and/or diffusivity. Using a Monte Carlo method, conducting lines containing a prescribed number of random triple junctions are simulated, wherein distribution of mass flux divergence determines initial values of ΔR/R. Moreover, by selection of an appropriate failure criterion, the sequence of cumulative failures is characterized by a log-normal-like distribution, which defines mean time to failure and corresponding standard deviation. In general, the model is in good agreement with experimental observations.

The solid state oxidation kinetics of Pb-In single-phase alloys were studied using AES (Auger Electron Spectroscopy) combined with sputter depth profiling. Samples containing 3, 30, 64 at% In were oxidized in air from room temperature up to 275 °C. At room temperature, the oxidation behavior for all three alloys was found to obey a direct logarithmic law. As the temperature is increased, the kinetics change from logarithmic to parabolic behavior. The transition between logarithmic and parabolic kinetics occurs between 150 °C and 175 °C for Pb-3 at% In alloy, and below 100 °C for Pb-30 at% In and Pb-64 at% In alloys. Using the solidius temperature as melting temperature of an alloy, the transition temperature for Pb-In alloys was observed to be approximately 70 – 75 % of the melting temperature.

Air oxidized Pb-Sn and Pb-Sn-In single phase alloys have been studied with scanning Auger microscopy. Line scans across grain boundaries combined with argon ion sputter etching revealed grain boundary oxidation. In the Pb-Sn samples, tin is preferentially oxidized with the grain boundary regions having a much higher percentage of tin oxide than the bulk surface oxide. In the Pb-Sn-In alloys, both tin and indium are preferentially oxidized with the grain boundary regions being enriched with tin and indium oxides.

Results from a phase stability study of the Bi-Pb-Sn ternary system and mechanical property data from the testing of the Bi-Pb-Sn ternary eutectic alloy are reported. It is found that the mechanical properties of the ternary eutectic alloy change considerably during cooling due to a solid state phase change at 79° C. After solidification, but prior to this phase transformation, the alloy exhibits brittle failure upon tensile loading. After the phase change high ductility is observed, bordering on superplasticity at low strain rates. Furthermore, having gone through the phase change once, the alloy remains ductile even after it is held at temperatures above 79° C. These results are interpreted in terms of the microstructures observed in the alloy.

The in-plane residual stresses of single crystal silicon wafers that were coated with filament-evaporated aluminum films have been obtained from measurements of strains produced by shadow Moir interferometry. The aluminum films were deposited as thin film layers over a 8.9cm diameter area on (100) p-type, 10.16cm diameter, 0.05cm thick single crystal silicon wafers, and the stresses were determined by an analysis that accounts for the finite dimensions of the samples. The aluminum film thicknesses varied from 70 to 78Onm. The aluminum films increased the inplane stresses of the wafers by 3 to 15MPa depending on the film thickness.