Advanced getter solutions at wafer level to assure high reliability to the last generations MEMS

The success of MEMS technology is related to the long term reliability and low cost of the final device. The wafer level package is a key technology to assure both long term stability and low cost. In an hermetically sealed MEMS, the degradation of the vacuum or inert atmosphere affect the working conditions of the devices, especially where moving parts are present. The most dangerous gas inside hermetically sealed MEMS is moisture, causing stiction problems of one part to another when the actuation of the moving part is performed by electrostatic actuation. A typical example of the stiction problem is the difficulty of moving mirrors in MEMS optical switches. Getters are a proven and experienced way to avoid vacuum degradation in hermetic environments and can selectively absorb gases such as moisture inside a filling gas. The current state of the art solution to integrate a getter inside a wafer to wafer bonded MEMS consists of 4" or 6" silicon or glass wafers with a getter film patterned inside cavities.