Effect of wafer-level silicon cap packaging on BiCMOS embedded RF-MEMS switch performance

In this paper, the effect of silicon (Si) cap packaging on the BiCMOS embedded RF-MEMS switch performance is studied. The RF-MEMS switches are designed and fabricated in a 0.25μm SiGe BiCMOS technology for K-band (18 - 27 GHz) applications. The packaging is done based on a wafer-to-wafer bonding technique and the RF-MEMS switches are electrically characterized before and after the Si cap packaging. The experimental data shows the effect of the wafer-level Si cap package on the C-V and S-parameter measurements. The performed 3D FEM simulations prove that the low resistive Si cap, specifically 1Ω·cm, results in a significant RF performance degradation of the RF-MEMS switch in terms of insertion loss.