High quality RF passive integration using 35 /spl mu/m thick oxide manufacturing technology

Abstract

The strong pressure of cost and size reduction in wireless industry makes the phone makers find new and revolutionary solutions for their products. Among the various approaches, the passive integration is the most attractive way. To achieve both goals of dramatic size reduction and additional cost reduction, we developed low cost manufacturing technology for RF substrate and high performance process technology for RF integrated passive devices by electrochemically forming thick oxide on Si wafer and using Cu metal and BCB material for metal interconnection and interlayer. The fabricated substrate is conventional 6" Si wafer with SiO/sub 2/ thickness of 25 /spl mu/m on the surface. This substrate showed the very good insertion loss of 0.03 dB/mm at 4 GHz, including conductive metal loss, in case of 50 /spl Omega/ coplanar transmission line (W=50 /spl mu/m, G=20 /spl mu/m), and provided cost-effective solution in RF passive integration. Based on these process technologies, we fabricated ultra high Q inductor on Si, which showed the maximum quality factor of 120. Several RFIPD (Integrated Passive Device) were also fabricated on thick oxide silicon and they showed good RF performances in spite of small chip size. In case of power divider, the insertion loss is below 0.5 dB and isolation is more than 25 dB. The 900 MHz low pass filter has 0.5 dB insertion loss and more than 25 dB attenuation at second and third harmonics. These will be widely utilized in hand-held module and system where the size or volumetric efficiency is a critical buying criterion.