By: Kevin Kröhnert, Markus Wöhrmann, Michael Schiffer, Georg Friedrich, Dzmitry Starukhin, Martin Schneider-Ramelow, Winfried Mayer, Tobias Chaloun, Thomas Galler, Christian Waldschmidt, Malte Schulz-Ruhtenberg, Norbert Ambrosius, Ulli Hansen.
In this work, we present the realized versatile hermetically sealed sensor packaging platform based on glass interposers which is applicable in industrial metrology, MEMS, photonics, life sciences and process automation application, among others. The sealed glass package can include passives and different active devices (radar, pressure, infrared sensors, etc.). Glass is used because it offers ideal properties for such a package by providing excellent chemical resistance, mechanical strength, advantageous RF characteristics and low costs. The capabilities of the platform are demonstrated in form of a radar level sensor which is operated at 160GHz. The level sensor includes our sensor packaging platform with an integrated SiGe ASIC and an RF port.
Due to the hermetic sealing of the ASIC inside, it is possible to utilize the package in hazardous environments, in this case in chemical microreactors. The package only measures 5.9 x 4.4 x 0.8 mm³ and uses TGVs (Through-Glass Vias) in this miniaturized sensor systems as vertical DC and RF interconnections with low parasitics which leads to low losses, while maintaining hermetic sealing. The performance of the TGVs regarding their reliability and their RF capabilities was investigated before and showed superior properties with less effort for fabrication. In this paper we will focus on all aspects of the final package with a fully functional radar ASIC inside. We consider the processing chain based on wafer-level processes, design and simulation, the analysis of the realized radar sensor demonstrator as well as the characterization and evaluation of the final package regarding reliability and hermeticity. The glass interposer processing steps and all the challenges which had to be solved for the via formation, the TGV filling and the hermetically sealing of the two interposers with the ASIC inside will be highlighted. The characterization and evaluation of the novel demonstrator system will consider RF performance, radar characteristics, reliability and hermetic sealing of the glass package.