Interface defects of bonded silicon wafers

The structure of interface defects of bonded silicon/silicon wafer pairs was investigated by high-resolution electron microscopy. Defects in the interface of bonded hydrophilic wafers appear after annealing at 1100 degrees C. They are identified as microtwins. Furthermore, bonded hydrophobic wafer pairs are characterized after analogous annealing by a disturbed interface region containing a large number of defects. In cross-sectional samples the defects are visible solely in atomic dimensions, having a typical V-shape parallel to {111} - lattice planes. Simulations of their HREM images revealed that they probably represent stacking-fault like defects caused by the incorporation of self-interstitials.