Reliability Study on Absolute Pressure Sensitive Chip Vacuum Packaging

The anodic bonding technology has been widely utilized in the packaging of the microelectromechanical systems (MEMS), but its relatively high bonding temperature, sometimes relatively weak bonding strength due to micro-bubbles generated along the bonding interface prevent its wider application. In this paper, the studying results demonstrate that can improved bonding strength to carry out the bonding process under vacuum. The experimental results show that the anodic bonding interface is uniform, much less bubbles, and its shear strength as high as 29Mpa. This technology can satisfy requirements of hermetic/vacuum packaging by used to absolute pressure sensors, gyroscopes, and so on. The investigation to absolute pressure sensors indicates that the internal and outside pressure difference has bigger influence to the micro cavity structure, this influence should be considered in designing the absolution pressure chip, especially in a thin sealing cavity, so that avoids the micro cavity to deform big too and even appears the collapsing phenomenon for smaller membrane thickness and strength.