Epitaxial yttrium iron garnet film for fabrication of high frequency on-chip inductors

Abstract

The application of epitaxial yttrium iron garnet (YIG) thin film on high frequency on-chip spiral inductors is investigated. The YIG thin film with the thickness of 3.6 μm was grown on GGG(111) substrate using the liquid phase method, which exhibits relatively high saturation magnetization 4πMs of 1615 Oe close to the bulk value of 1750 Oe and low initial coercivity Hc of 0.5 Oe that minimizes the hysteretic losses. Subsequently, the spiral inductors were directly fabricated on the YIG/GGG(111) substrate. The results show substantial improvement in the optimum operating frequency and self-resonance frequency of the on-chip spiral inductor with the YIG thin film with an increase of 50% up to ∼7.5 GHz and 14.2 GHz, respectively, implying that on-chip spiral inductors with the YIG thin film can be applied to much higher frequency RF circuits.