Enhanced electrical performance of Ag-Cu thin films after low temperature microwave processing

In the present study, thin films of binary Ag-Cu alloys with different Cu content were prepared by a cosputtering technique and then annealed by microwave heating. The metallographic and electrical properties of the thin films were observed experimentally. It was found that the electrical performance of Ag-Cu thin films enhanced after microwave processing when compared to vacuum annealing. Based on the fact that Cu has a low solubility in Ag, it was chosen as the alloying element. The low solubility favored segregation of Cu at the surface and grain boundaries. This prevented Ag grain boundary diffusion and agglomeration. The as-deposited thin films were more resistive when compared to the microwave processed films. Comparison of the two postdeposition annealing techniques, microwave and vacuum, showed that microwave annealing is a clean, faster, and efficient process that can improve the electrical performance of Ag-Cu thin films. Results from this investigation demonstrated that microwave annealing is a suitable replacement of more expensive manufacturing techniques currently used in the field of interconnects technology.