A knowledge of interfacial mechanical properties is of considerable importance to the areas of oxidation, corrosion, metallization, and composite materials. We have developed an experimental apparatus capable of simultaneous measurements of elastic and anelastic properties of materials in controlled atmospheres (10-6 to 104 Pa) from 25 to 1000°C. The apparatus employs the technique of dynamic reasonance in which a material's mechanical resonance spectrum can be determined over a range 102 to 105 Hz with resolution ±0.001 Hz. This resolution has enabled us to determine the mechanical properties of films as thin as approximately 10 nm.

We shall present resonance results for thin films (∼100 nm) of nickel and gold on sapphire substrates. These results suggest that nickel films on sapphire are adherent, i.e., cyclic strain is continuous at the film-substrate interface, over a range of temperature about the film growth temperature; whereas gold films show nonadherent behavior at all temperatures studied.

We have investigated the electromigration resistance of Al-Si/Ti multilayer interconnects. For comparison Al-Si and Al-Si/Ti/Al-Si films were also prepared. The linewidths ranged between 1.6 and 5, um. A temperature-ramp resistance analysis was applied at direct wafer level, to detect electrically transport of material and derive the electromigration kinetic parameters in test vehicles with different geometries.

Interdiffusion barrier characteristics of molybdenum thin films with Alusil(Al-1% Si) is studied between 733 and 7 63 K via sheet and contact resistance measurements, Rutherford backseattering spectrometry, secondary ion mass spectroscopy, and x-ray diffraction analysis. The results indicate that thermal annealing of Mo/Alusil thin film couples leads to MoAl compound formation initially as a nonplanar front, but extensive annealing results in complete transformation of Alusil to MoAl12 and a significant increase in contact resistance. The interdiffusion kinetics is studied and implications of these observations to VLSI device characteristics is discussed. Based on these results a safe time-temperature processing regime is proposed.

Alumina coatings made by the sol-gel process using aluminum sec butox-ide can be made with variable surface area and porosity by firing on dense alumina substrates in the firing range 700 to 1000 C. These coatings are found to have large (over 100 MPa) compressive stresses and to cause a small but significant strengthening of the substrates. Within this firing range the surface area decreases while both the internal stress and strengthening effect increase with increasing firing temperature. Wear rate values are high but decrease with increasing firing temperature.

Thermal cycling of silicon solar cells heated with incandescent light or using an in-situ heating stage on an optical microscope caused unexpectedly rapid oxidation of the electrodeposited copper current collecting grid. Unusually fine buckling and spal ling of the oxide film also occurred at temp. as low as 180°C. These effects appear to stem from the very fine columnar grains and high defect content of the copper ribbons and some Cl residue from the electrolyte. With vapour-deposited Cu, similar relatively rapid oxidation and spalling were also observed. Origins of the high oxidation rates, the large compressive stresses within the oxide and the low-temperature spalling are discussed.