Pt-RuAl bilayers as a model system for Pt wire bonding of high-temperature RuAl electrodes

For the application of RuAl as a metallization in wireless high-temperature surface acoustic wave devices an electrical connection between the RuAl interdigital transducer and an antenna is necessary. Such an electrical contact can be realized e.g. via wedge-wedge Pt wire bonding which is established on Pt films. To transfer this technology to the RuAl system, our approach is to deposit a Pt layer on the RuAl film as a contact pad. Pt-RuAl bilayers are analyzed concerning their high temperature stability up to 900 °C in air and under high vacuum by X-ray diffraction, cross section analysis and Auger electron spectroscopy. Pt wire bonding is applied on the as-prepared bilayers. The Pt-wedge–Pt-RuAl samples are heat treated as well and the interface between the Pt wedge and Pt-RuAl bilayer is analyzed. The results show that interdiffusion between the RuAl and the Pt leads to a mechanically stable film-wedge contact.