Processes for the Integration of MEMS and CMOS

Abstract

Wafer to wafer bonding was an enabling technology for MEMS because it provided the needed protection for the devices by capping them at the wafer level allowing them to survive in the required operating environments such as the automotive environment. The two earliest bonding processes used for this wafer level capping were anodic and glass frit bonding. Due to the constant pressures for cost reduction, size reduction, performance increase, increased integration, and shortened product life cycles the integration of MEMS devices with CMOS based circuitry is increasingly being considered and implemented. Consequentially, bonding, whether wafer to wafer or chip to wafer, has the additional role of being an enabling technology for the integration of CMOS and MEMS device. In this technology, the bond joint typically has multiple roles such as providing mechanical strength, electrical signal conductance, and sealing against various environmental agents or for vacuum encapsulation.