Low-profile and chip-scale RF FEM using Si-interposer technology

In this paper, we have developed the smallest hybrid-IC RF FEM (front-end module) using the thin-film integration and embedded-IC technology. All kinds of passive devices are integrated on a silicon substrate using a standard thin film process and active devices are embedded in cavities of the silicon substrate. An organic lamination process is used to fill a gap between the silicon and embedded IC. The signal via on the laminated organic is made using an UV laser machine. The RF FEM is consisted of three active ICs, PA, LNA, and SPDT switch, where ICs are embedded in the silicon cavity. The depth of the silicon cavity is 120µm. Thin film capacitors and spiral inductors integrated on the silicon substrate are used for impedance matching or DC blocking. The measured insertion loss of the SPDT switch was 0.7 dB at 2.45 GHz and the LNA and PA shows more than 20 dB of gain respectively. The size of fabricated RF-FEM is only 2.5×4.1×0.2 mm3.