Integration of inductors on silicon chips is becoming more and more relevant for monolithic electronic applications. In this Letter, we investigate the impact of minor hysteresis loops in an integrated inductor with spiral geometry sandwiched between two soft magnetic layers made of MoNiFe/Cr multilayers. Despite high magnetic susceptibility and low coercivity of optimized multilayers, we find that the inductance is strongly dependent on the AC voltage applied to the device, showing a bell-shaped behavior. Comparing the measured inductance with magneto-optical Kerr effect and vibrating sample magnetometry measurements, we show that the low-signal behavior is limited by domain wall pinning/depinning, which determine the effective susceptibility associated with minor hysteresis loops driven by the applied AC voltage.

We report on the formation of gas bubbles during the release of MEMS devices using buffered oxide etch. Several approaches to mitigate the problem are proposed and tested together with a qualitative study of the phenomenon. The chemical reaction behind such phenomenon and the influence of defects and topography is discussed. Finally, a comparison with the HF-vapor release technique is shown.