An enhanced quasi-monolithic integration technology for microwave and millimeter wave applications

A new technology for integration of high frequency active devices into low cost silicon substrate has been introduced. The novel fabrication process gives excellent advantages such as extremely low thermal resistance, and a much lower thermo-mechanical stress than the earlier quasimonolithic integration technology (QMIT) concept . This highly improves the packaging lifetime and electrical characteristics of the active devices. The fabrication process is simple and compatible with fabrication of high-Q passive elements. Successful integration of high-Q passive elements on low resistivity silicon substrate in this technology has been possible for the first time. In comparison to the earlier concept of QMIT, elimination of air-bridges in this technology not only reduces the parasitic elements 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. Furthermore, the enhanced QMIT can be considered as an organic deposited multi chip module (MCM-D), which is a potential candidate for integration an system on a package (SOP) at microwave and millimeterwave frequencies.