Thermally Stable Ag Thin Films Modified with Very Thin Al Oxide Layers

Ag has long been of interest for use as a low-resistivity electrode material, but the problem of agglomeration caused by annealing must be resolved. One of the solutions is alloying Ag, but this often causes an increase in electrical resistivity. In this study, thermal stability of Ag thin films modified with thin Al oxide layers was investigated from the viewpoints of surface morphology and resistivity. It was found that agglomeration was suppressed in the multilayer films even after annealing at 600 °C, similarly to Ag(Al) alloy films, which were investigated previously. As a result, it was suggested that the presence of the Al oxide layers at the film surface and interface played a major role in suppressing agglomeration in Ag(Al) films. Moreover, the resistivity of the multilayer film was 1.8 µΩ cm, which was much lower than that of alloy films. Consequently, to achieve both agglomeration suppression and low resistivity, the structural modification of the Ag films using Al oxide layers is more useful than alloying the films