Modular Monolithic Microelectromechanical (MEMS) System Technology (M3S)
Final technical rept. May 1997-Apr 2002
CALIFORNIA UNIV BERKELEY REGENTS OF THE UNIV OF CALIFORNIA
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Surface micromachining with monolithic integrated electronic evaluation circuits is an attractive technology for low-cost, highly compact sensors. Unfortunately, past monolithic sensorcircuits processes suffer from technology complexity resulting from the combination of two complex fabrication processes. The complex interactions slow down progress and preclude a straightforward upgrade path when a better circuit process becomes available. The technology developed here overcomes the disadvantages. By fabricating the mechanical structures first and embedding them in a planarized wafer, it achieves a high degree of separation between the two processes. In fact, the mechanical structures are fabricated by Analog Devices, while a CMOS foundry adds electronic circuits. New circuit options are added by simply sending the wafers to a different foundry. A full complement of gyroscopes and accelerometers fabricated in the modular process demonstrates the practicality Of the approach. Compared to conventional processes, the sensors benefit from unproved circuits performance and higher integration capability. A 5-V only gyroscope operating at ambient pressure underscores the flexibility of the approach to implement functions that normally require special technologies, such as high voltage transistors or vacuum packaging. The simpler approach greatly reduces cost and should be of value particularly in cost-sensitive applications such as smart ammunition or micro-air-vehicles.
- Electrical and Electronic Equipment