Low-cost vacuum packaging has become one of the most important challenges in the MEMS industry for a number of emerging applications including resonant sensors and radiofrequency MEMS. Some essential features of a MEMS package include small size, vacuum/ hermetic capability, integrated sealed feedthroughs, wafer level processing, stability in harsh environmental conditions, and low cost. Simultaneously meeting all of these criteria is a challenge in the field of MEMS sensors and microsystems.
Researchers at the University of Michigan have developed a low-cost manufacturing method for vacuum or hermetically packaged micromachined device with vertical feedthrough wherein a minimum amount of die area is used. In this process, the MEMS device is fabricated in a conventional fashion with p++ layers bonded to a glass substrate. The electrical connections are formed by using metal lines on glass, where a combination layer of Ti/ Pt/ Au is typically used (Au on top layer). The feedthroughs are substantially vertical and are formed through the glass substrate.
Applications and Advantages
- Vacuum and/or hermetic packaging and feedthrough technology for micromachined or MEMS devices such as DWP sensors, in particular for vibratory gyroscopes
- Low susceptibility to damage
- Minimal die area consumed
- Easily formatted for surface mount applications
- Wafer level procedure with standard processing
- Process can be performed after MEMS-nl-fabrication