High-Performance RF Inductors and Capacitors Using the Reverse Trench Structure of Silicon

We propose new passive device structures using deep silicon trenches. High-aspect-ratio reverse trench structures coated with copper can be used to make signal lines of the spiral inductor, and a deep trench around the MIM capacitor can be used as a signal isolation wall after back-side thinning. A laminated organic is used to fill the trench. It is possible to make a 10:1 ratio metal pattern maximally, and all signal lines are fixed and isolated due to the laminated organic. Though the spiral inductor is realized on lossy silicon, its Q-factor is higher than 40 at 2 GHz. The fabricated 0.9 GHz LPF adjusting the reverse trench process has only 0.5 dB insertion loss with a very small size.