YIG thin film for RF integrated inductor

The yttrium iron garnet (YIG) thin films prepared by the sol-gel method and rapid thermal annealing (RTA) process for integrated inductor are investigated. The X-ray diffraction (XRD) results indicate that the YIG film annealed above 650 °C is poly-crystalline with single-phase garnet structure. Moreover, it can be found that the initial permeability μ _i, saturation magnetization M _S and coercivity H _c of these YIG films increase with increasing RTA temperature. Low temperature annealing after crystallization can further improve the magnetic properties of YIG film. Thereby, a planar integrated inductor in the presence of Si substrate/SiO₂ layer/Y_2.8Bi_0.2Fe₅O₁₂ thin film/Cu spiral coil structure is fabricated successfully by the standard IC processes. Due to the magnetic enhancement originated from YIG film, the inductance L and quality factor Q of the inductor with YIG film are improved in a certain frequency range.