PARTS SYNTHESIS APPROACH FOR 3D INTEGRATION OF MEMS AND MICROSYSTEMS LEADING TO SYSTEM-ON-PACKAGE

This paper aims at developing Parts Synthesis Approach (PSA) for three-dimensional integration of MEMS and Microsystems leading to System-On-Package (SOP). This eliminates the interconnection related problems that arise when MEMS and its associated circuitry are packaged separately. A gas sensor array microsystem illustrates this. The novelty is that the electronics block at room temperature and the sensor at sensing temperature (250 degrees C-550 degrees C) coexist in the same SOP. Targeted specifications of the SOP are low power budget per sensor and low cost. Thermal and structural modelling and analysis has been done using ANSYS software. The SOP is modular in design and construction. In PSA the six physical parts of the SOP are first designed, optimized and fabricated individually and then integrated to form the desired SOP. The substrate is an integral and active part of the SOP. Power management is done by reducing thermal mass of the hotplate, increasing thermal resistance between the hotplate and the rest of the substrate and using pulsed power operation. Designs of the cavity structure, the coverlid and the bottom support help in thermal management. This technique circumvents the difficulties of forming deep cavities in LTCC technology. Since the six different parts of the SOP are fabricated separately and then integrated together the final yield is high. Designing in parallel reduces required time and cost.