Integration of 0/1-level packaged RF-MEMS devices on MCM-D at millimeter-wave frequencies

This paper reports on the optimization of 0/1-level packaged CPW lines and RF-MEMS switches up to millimeter wave frequencies. The 0-level package consists of an on-chip cavity obtained by flip-chip mounting a capping chip over the RF-MEMS device using BCB (BenzoCyclo-butene) as the bonding and sealing material. The 0-level coplanar RF feedthroughs are implemented using BCB as the dielectric; gold stud-bumps and thermocompression are used for realizing the 1-level package. The 0-level packaged switches have been flip-chip mounted on a multi-layer thin-film interconnect substrate using a high-resistivity Si carrier with embedded passives and substrate cavities. The insertion loss of a single 0/1-level transition is below -0.15dB at 50GHz. The measured return loss of a 0/1-level packaged 50Q CPW line remains better than -19dB up to 71GHz and better than -15dB up to 90GHz.