Chip scale package of a MEMS microphone and ASIC stack

Most MEMS microphone systems on the market are packaged by conventional chip bonding and wire bonding.. A significant step towards miniaturization was achieved earlier by applying flip-chip bonding to MEMS microphone packaging. This technology is called chip scale MEMS package (CSMP). Thereby the package size could be reduced to 2.8 × 2.05 × 0.9 mm³ compared to a standard size of 3.76 × 2.95 × 1.1 mm³. In this paper the next step in miniaturization is presented. A further reduction to a total size of only 2.05 × 2.05 × 0.95 mm³ was achieved by placing the ASIC directly under the microphone chip inside a cavity in the substrate. This design is called stacked CSMP.