Improvement of the multilayer morphology (alumina/Cu/YIG/Cu) to characterize YIG thin film

The aim of our study is to characterize yttrium iron garnet (YIG) thin film for its applications in the microwaves and magneto‐optical domains. For this purpose, we have manufactured a microinductor by deposition of YIG film between two copper layers on an alumina substrate. Multilayers have been deposited by radio‐frequency magnetron sputtering technique. Thin films of YIG are amorphous after deposition; a post‐thermal annealing at 740 °C for 2 h is necessary to obtain satisfactory magnetic properties. In this work, we have studied the effects of different parameters concerning the substrate surface state, deposition and post‐thermal treatment of YIG and copper thin films on their structure and morphological properties. We have come against several mechanical and electrical problems: crack formation, detachment of YIG or Cu films from the substrate, deterioration of Cu films, open or short circuits. The roughness of alumina substrate and the annealing mode play an important role on the quality of the microinductor prototype. After several tests by varying different parameters, we have established a protocol permitting to manufacture a prototype of good quality. This prototype is characterized using: profilometry, scanning electron microscopy, X‐ray diffraction, vibrating sample magnetometry, and a precision LCR meter.