A preparative technique for spiral thin-film transformer at GHz frequency band

This paper present a preparative technique for spiral thin-film transformer with ferrite magnetic core. RF magnetron sputtering is used to prepare ferrite thin film on SiO₂ layer. Compatible problems of thin film with IC technology are observed by SEM. The problems are resolved through sputtering parameters modification and heating treatment addition. S-parameters are measured at 10 MHz-20 GHz. The result shows that The experience result shows, magnetic core thin-film transformer with 15:15 ratio-turn can obtain the maximal transmission efficiency 80.9% at 10 MHz-20 GHz, and the air core transformer can obtain the maximal transmission efficiency 55.4% at same frequency range. Ferrite thin film can improve the transmission efficiency evidently.