Broadband Microwave Signal Dissipation in Nanostructured Copper Oxide at Air-Film Interface

Contactless broadband microwave spectroscopy (a.k.a., broadband dielectric spectroscopy (BDS)) enables the accurate operando analysis of the electrical and magnetic properties without compromising the kinetic conditions of the experiment. The BDS method is sensitive to the actual electronic structure of species, and it is most relevant to redox reactions involving charge-transfer. In this paper, using BDS, we have studied and characterized the oxidation of a copper layer in a purposely built prototypical 3-D integrated circuit (3D-IC) during cycled high-temperature storage. We show that the microwave signal loss in these devices is attributable to the energy dissipation through the signal's interactions with the copper oxidation product. The results demonstrate that contactless BDS could be leveraged into an excellent metrology for applications that use metal oxide as sensing elements.