Post-CMOS integration technology of thick-film SOI MEMS devices using micro bridge interconnections

This paper reports a new post-CMOS process to integrate thick (>10 mum) SOI MEMS devices after standard CMOS process, which requires only three additional photomask steps. The additional MEMS processes are not severe and critical for the integrated CMOS devices. In this technology, high aspect ratio SOI MEMS devices and CMOS integrated circuits are electrically connected with 'micro bridge interconnection' fabricated by batch processing. Metal interconnections are placed on oxide bridge structures that are connecting between electrically isolated CMOS areas and MEMS areas in active layer of thick SOI wafer in order to connect the MEMS electrodes to terminals in CMOS circuits. This fabrication technology can be applicable widely to high-dense integration of monolithic CMOS/MEMS on thick-SOI wafers.