Abstract: Metal based wafer bonding for WLP has several advantages including enhanced hermeticity and it facilitates vertical integration. These advantages allow for reduction in die size and cost savings with improved device performance. Until recently, first level packaging for MEMS was done using glass frit or anodic bond process. The glass based bonding methods are used in over 80% of volume MEMS production for high volume products such as pressure sensors, accelerometers and gyroscopes. All of these products as well as RF resonators require vacuum packaging. The physical properties of glass and frit sealing materials translate into seal geometries that are in the range of 100’s of microns.
Using advanced bonding and bond alignment equipment, in combination with metal bonding methods significant improvements in COO and device performance can be realized.