New generation quasi-monolithic integration technology (QMIT)

A new technology for integration of high frequency active devices into low cost silicon substrates has been introduced. The novel fabrication process gives excellent advantages such as extremely low thermal resistance, and a much lower thermal stress than the earlier QMIT concepts (Wasige et al., 1999; Joodaki et al., 2001 and 2002). This highly improves the packaging life-time and electrical characteristics of the active devices. The fabrication process is simple and compatible with fabrication of low-loss and high-Q passive elements. Successful integration of low-loss high-Q passive elements on low resistivity Si-substrates in this technology has been achieved for the first time (Joodaki et al., 2002). In comparison to the old concept of QMIT, the elimination of air-bridges in this technology not only reduces the parasitics but also enables the fabrication of the rest of the circuit after measuring the microwave characteristics of the embedded active devices. This makes very accurate microwave and millimeter-wave designs possible. Using the new fabrication process, microwave and millimeter-wave circuits (with both coplanar and microstrip lines) containing power devices have for the first time been possible.