The wafer bonding technology, such as the anodic bonding, the eutectic bonding, the fusion bonding, the polymer bonding and the low-temperature glass bonding techniques, is applicable for vacuum sealing of microsensors or packaging of micromachine, especially the anodic and the eutectic bonding techniques may assure hermetic sealing and high interfacial bonding strength in sensor packages. In this study, my attention is concentrated on the anodic bonding technique using high voltage and application of fracture mechanics.
The anodic bonding apparatus was constructed for bonding of silicon and glass wafers, and the interfacial fracture toughness, which is suggested for a measure of bonding strength, was measured on the interface of bonded wafers using the blade test. Most of wafer bonding specimens can be reduced to the interface crack problem of the two infinite strips, where the energy release rate, the phase angle and the T-stress were evaluated by applying interfacial fracture mechanics and anisotropy elasticity, and the novel method was proposed for calculating the interfacial T-stress using conservation integrals. Also the universal relation of the T-stress, which is very useful relation for a sandwiched specimen with adhesive layer, was derived by employing path independency of the mutual integral.
The fracture mechanics approaches were developed for the wafer bonding test, and the blade test, which is proved to be useful method, was employed suitably in order to measure the interfacial fracture toughness of the anodically bonded wafers.
