Effects of Al ₂O ₃ films on the reliability of Au/Al joint

Effects of Al ₂O ₃ films in the system of Au/Al joint widely used in semi-conductor devices at present have been studied. In the experiment, a thin film of Au/Al ₂O ₃/Al was used, and the diffusion of Au atoms across through Al ₂O ₃ films and the formation of intermetallic compound at temperatures between 25°C and 500°C were observed by using Auger electron spectroscopy, X-ray photoelectron spectroscopy, electric resistance measurement and secondary ion mass spectrometer with using ¹⁸O as a tracer. It has been cleared from test results that, (1) Au diffuses through Al ₂O ₃ films and reacts to Al, (2) as temperature rises up, the intermetallic compound grows in an island formation for Au/Al ₂O ₃/Al system, and (3) the behavior of its growth varies with the presence of oxygen in the atmosphere applied. On the basis of the above results, the effects of Al ₂O ₃ films on the reliability of Au/Al joint are discussed in this paper.