The dependence of electromagnetic noise suppress characteristics on magnetic and high-frequency properties of FeCoSiO thin films

Soft magnetic granular FeCoSiO films are fabricated using radio frequency magnetron sputtering. By using microwave probe station, integrated-type electromagnetic noise suppressors based on a coplanar waveguide transmission line and incorporated with a SiO2 dielectric and a granular FeCoSiO magnetic thin film with excellent high frequency and soft magnetic properties are investigated. The signal attenuation is less than 0.5 dB in the entire tested frequency range for the bare CPW transmission line, thereby indicating that the entire input signal can unhindered pass the CPW transmission line. With FeCoSiO magnetic film deposited on CPW transmission line, the signal attenuation is distinct increases, and an obvious absorption resonance peak is present. The amount of signal attenuation at resonance point increases with increasing thickness of the FeCoSiO thin films and the maximum value of S21 is about −39.7 dB at a film thickness of 1200 nm. The loss peak frequencies increase with the increasing film thickness, and are higher than the natural ferromagnetic resonant (FMR) frequencies of thin films. The shift of loss peak for each film can be explained by demagnetizing field and natural FMR frequencies. It implies that FMR is mainly responsible for the loss generation. The frequency-dependent transmission signal attenuation (S21) of the CPW: (a) without films and (b) integrated with FeCoSiO films of different thickness values.160