High-Q copper inductors on standard silicon substrate with a low-k BCB dielectric layer

High-Q Cu inductors using low-k benzocyclobutene (BCB) dielectric as an interface layer have been fabricated on a standard CMOS-grade silicon substrate. Metal ohmic loss and substrate loss, the two major factors that degrade the Q-factors of on-chip inductors, are suppressed by the employment of electroplated copper and the BCB dielectric, respectively. Quality-factor as high as 25 was obtained for a 1 nH inductor at 2 GHz. The inductor fabrication process is low-cost and low-temperature, making it suitable for a post-IC process for high-performance RFIC's and MMIC's.