Investigations of the interface strength of bonded silicon wafers

Tensile tests were applied to determine the strength properties of bonded contacts (prepared by Direct Wafer Bonding) in micromechanical components. In addition to material properties, as the specific interface energy, the measured fracture stress depends also on the geometry of structures in the bonded interface. A fracture mechanics approach allowed to separate these factors and, thus, to determine the interface energy to testing of small components. The results of tensile tests are compared to data obtained from the crack propagation method on whole wafers. The investigation proved that tensile tests can be applied to characterize the quality of bond processes during micromechanical device manufactoring.