Improvement of bonding time and quality of anodic bonding using the spiral arrangement of multiple point electrodes

The anodic bonding, a non-intermediate bonding technology, that is mainly used in glass to silicon wafer bonding, has become one of the important steps in the process of microelectromehanical systems (MEMS). However, anodic bonding may produce gas trapping in the bonding interface and affect the bonding quality. The point electrode can solve the gas-trapping problem, because the way of bonding region starting from the cathode tip and middle of the wafer can avoid the gas trapping. However, the bonding time is too slow. The planar cathode can bond large area in a short time, but the gas-trapping problem may get worse, thus the bonding quality is not quite well. In this paper a new method is developed, using multiple point electrodes in a spiral arrangement for not only solving the gas-trapping problem, but also significantly reducing the bonding time in anodic bonding.