A novel method for the fabrication of integrated passive devices on SI-GaAs substrate

A novel process is developed for fabricating cost-effective, high-yield, and high-quality integrated passive devices on SI-GaAs substrate. Various material and processing approaches to thin film resistors (TFRs), spiral inductors, and metal-insulator-metal (MIM) capacitors are evaluated in terms of cost, yield and device performance. For better precision in TFR resistance, we modify the bottom metal manufacturing process. For higher spiral inductor quality factor (Q-factor) and yield, a much thicker second metal and a sputter-etching process is presented. For higher MIM capacitor yield, some optimised mechanisms are used. To further decrease the cost and increase the yield, SU-8 photo resist is firstly presented as a novel material for forming the final passivation layer to replace the traditional SiN_x. A wireless local area network balun, low-pass filter and digital cellular system power divider are demonstrated by using this novel manufacturing process; they show very good RF performances in spite of theirs small chip size and low cost, compared with those of the reported literature.