The Research Of High Frequency Thin-film Inductors

Thin-film inductors are important components in monolithic radio frequency (RF) circuits,such as voltage-controlled oscillators(VCO),low-noise amplifiers and passive-element filters.It was important about the researches of material,design of inductors and manufacture of devices.In order to increase inductance,operating frequency and quality factor but reduce capacitor loss,the thin-film inductor was prepared using high permeability material for conductor.Static and dynamic magnetisms of the magnetic thin film were investigated.And we also studied the high frequency performance of inductors.The main works were as follow:1.The choice and performance research of inductor material.The Co₉₂Zr₈ thin film of high permeability was investigated systematically.Through changing process,it was shown that Co₉₂Zr₈ thin film had well in-plane uniaxial anisotropy. The coercive force of easy axis and hard axis were both lower than 0.203 kA/m.The anisotropy field H_k was 2.4 kA/m.The saturation magnetizationμ₀M_s was 1.2 T.The relative initial permeability of Co₉₂Zr₈ could reach 400.2.The design and preparation of thin-film inductors.Firstly,U inductors were researched theoretically.Then,the millimetric theoretical inductors were prepared. Last,micron inductors were designed and prepared.The Cu and Co₉₂Zr₈ inductors were prepared by radio frequency(rf) sputtering onto 10×10×0.42 mm³ SiO₂/Si substrates.The parameters of the two inductors were the same with the line width w=1.50 mm,space d=2.75 mm and thickness t=200 nm.3.The performance of high permeability thin-film inductors.From the results,it was shown that the inductance of the Co₉₂Zr₈ inductor was larger than that of Cu inductor when frequency from 1 MHz to 110 MHz.And at 60 MHz,the inductance of the Co₉₂Zr₈ inductor was 5.0μH,which was enhanced by five times from 1.0μH of the Cu inductor.The capacitance and quality factor of the Cu inductors were a little bit larger than that of the Co₉₂Zr₈ inductor.It was shown that the inductor performance of magnetic inductor is good.