Wafer-Level Packaging Using High Force Bonding of AlGe

The AlGe high force bonding shows an increased capshear strength, which is caused by the increased bond force and resulting in thinner eutectic metal layers. The uniformity of the bonded structures over the wafer leads to a higher yield. The new heater design with its double side air cooling, with special thermal isolation and flange cooling, leads also to a better post bond bow of the bonded wafers. In summary one can say the new features lead to a high yield due to the homogeneity of the temperature and bonding force distribution in the XB8. In general for device manufacturers the key motiviation to transition to metal based waferlevel bonding is the increased hermeticity which improves device functionality but more importantly enables the continued scaling of the device to smaller sizes. But it also needs a better temperature and bond force homogeneity in the bond equipment itself. The economic and technological advantages of metal bonding in MEMS wafer-level packaging are clear and these methods will continue to increase in use as market became more consumer oriented and integration with other components increases.