A Novel Fabrication Technology for Waferlevel Vacuum Packaged Microscanning Mirrors

This paper presents a novel fabrication technology for wafer level hermetic encapsulated MEMS micro scanning mirrors. This wafer level package enables vacuum operation of the electrostatically driven resonant scanners reducing the required driving voltage and enhancing the mechanical deflection angle even at resonance frequencies of more than 100 kHz. Two nearly independently structured 30 microns thick epipoly silicon layers offer a high design variability due to the possibility to create active silicon structures with two different thicknesses. A buried isolated interconnection layer between the two thick epipoly silicon layers enables the fabrication of lateral feedthroughs which are vital to set up a hermetic package. A structured glass wafer with up to 900 microns deep cavities seals the device wafer at the front side via anodic bonding. An AuSi-eutectic bonded silicon wafer completes the wafer scale vacuum packaging process.