(Invited) CMOS MEMS Integration

Abstract

The "More than Moore" trend in the microelectronics industry is driving a renewed interest in mixed-physics CMOS MEMS integration. Integration becomes a necessity for multi-component microsystems, where interconnect issues are significant. Integration also drives down parasitic capacitances and provides opportunities for ultra-low-power microsystems. Several monolithic approaches exist that create MEMS from the layers in the back-end-of-line CMOS stack or by adding materials on top of the CMOS stack. These processes have been used to create a variety of microsystems including inertial sensors, RF tunable capacitors and probe manipulators. Process extensions include addition of sensitizing polymers by inkjet for gravimetric gas chemical sensors, etch of intermediate metal layers followed by polymers fill for capacitive chemical sensors, and plasma polymer deposition on micro-meshes to form diaphragms. The chip-stacking approach to integration is still in its infancy but benefits from the rapid maturation of technologies for chip thinning and for through-silicon vias.