Abstract
High operation frequency, miniaturization, functionality, and reliability are the trends of future wireless and portable communication productions. Circuit integration becomes essential for the development. The shrinking and integration capability of active devices greatly exceeds that of passive ones. If both the active and the passive devices are to be integrated together, the thin film process technology for passive devices will play a crucial role in future development. In this study photolithography and wet etching techniques are utilized to fabricate thin film inductors. By using Vector Network Analyzer and Cascade coplanar probes, scattering parameters of the thin inductor were measured. With the help of ADS and SONNET simulation analysis, effect of geometry and ground shield pattern on the high frequency characteristics of the inductors, e.g. quality factor, inductance and self-resonance frequency were discussed. According to our experimental results, the inductance of rectangular inductor was found to be higher than that of square inductor by one order of magnitude. Nevertheless, the rectangular inductors have a lower self-resonance frequency due to the larger surface area, and hence larger parasitic impedance. Using a patterned ground shield beneath the inductor was planned to enhance quality factor of the inductors. Although we are not able to achieve the goal, but electromagnetic simulation results indicated that only the inductors having appropriate optimization of geometry and process conditions can gain the advantage from pattern ground shield. The optimum performance of the thin film inductor fabricated was found to be QMax = 2.65 and fsr = 14.82 Ghz.