A New System-on-a-Chip (SOC) Technology -High Q Post Passivation Inductors

摘要

This paper presents a new SOC scheme by adding highＱ(>15) inductors on top of 1C passivation layer. Affiliated with such a high Ｑ inductor, a high performance RF CMOS chip can be achieved, which may replace some applications of GaAs chips. The highＱvalue of the inductor is attributed to the large gap formed by the thick polyimide located between the inductor body and 1C passivation layer, as well as the thick metal traces of inductors. Conventional 1C front-end process technology cannot offer these advantages as it places the inductor closer to the silicon substrate, and its metal is thinner than 2μm The manufacturing cost of post-passivation inductor is also much lower than that of font-end 1C process in that the post passivation inductors can be fabricated in a more relaxed manufacturing environment Two kinds of inductor bodies, copper and gold, have been developed, respectively. At 5 GHz, the post passivation inductor demonstrated aＱfactor as high as 24, which is much greater than that of the ones formed by 1C front-end process that are positioned under the passivation layer (Ｑvalue lower than 10). The reliability results of the new SOC scheme will be also presented.