Nucleation, growth, and aggregation of gold on polyimide surfaces

The growth of ultrathin gold films on polyimide (PI) surfaces and the stabi lity of the films upon thermal annealing have been studied using a combinat ion of various techniques. With scanning electron microscopy (SEM) we obser ve that, at room temperature, the Au film initially grows by nucleation of compact Au islands. With increasing metal coverage, the clusters partially agglomerate to produce a wormlike structure. Finally, percolation, hole-fil ling, and continuous thin-film growth are observed. To evaluate the thermal stability of the Au/PI system, annealing at various temperatures was perfo rmed on films that displayed the wormlike structure. SEM results indicate s trong temperature-dependent changes in film morphology. Finally, from our S EM data we determine contact angles, allowing us to estimate interfacial an d adhesion energies.