Abstract
3D integration of micro electromechanical systems (MEMS) together with integrated circuits (ICs) brings in several specific requirements. For instance, 3D integration of the different modules that make up a Tire Pressure Monitor System (TPMS) is a real technological challenge. A TPMS typically consists of a MEMS device, an application specific integrated circuit (ASIC), a power supply, a radio and an antenna. As part of the European project e-CUBES, a miniaturized TMPS demonstrator is being fabricated in which the MEMS, ASIC and radio devices are 3D integrated into a heterogeneous system. Au stud bump bonding (Au SBB), SnAg micro bumps and Cu/Sn solid liquid interdiffusion soldering (SLID) are used for electrical and mechanical interconnection between the individual layers. W filled through silicon vias (TSV) are applied through the transceiver chip whereas two different types of TSVs are demonstrated for the cap wafer of the MEMS device. The maturity of the applied technologies spans from brand new to well established, but combining these into a single 3D integrated device is nevertheless a significant logistical and technological challenge. As a follow-up to previous publications, this paper will focus mainly on the technological studies performed for the Au SBB, the SLID connections and the TSVs for the MEMS cap wafer. Visual, electrical and mechanical characterization will be presented, including reliability studies. Some results from the final miniaturized TPMS demonstrator will also be presented.
