Growth, shrinkage, and stability of interfacial oxide layers between directly bonded silicon wafers
Models for the growth and shrinkage of an interfacial oxide layer and for the stability of the interfacial oxide layer are formulated. Predictions of these models are compared to results obtained by high-resolution transmission electron microscopy. Wafers containing different concentrations of oxygen interstitials are bonded. Depending on the starting concentration of oxygen interstitials in the wafers, the interfacial oxide layer grows or shrinks during long-time annealing at high temperatures. For much shorter annealing times, local disintegration of the oxide layer may occur, which is less severely influenced by the concentration of oxygen interstitials. Rather, it depends on the thickness of the interfacial oxide layer. The influence of rotational misorientation is examined by rotating wafers around their common axes perpendicular to a wafer plane and subsequent bonding. Above a critical angle of about 1-3°, a continuous oxide layer is formed, where below this critical angle, sufficiently thin oxide layers disintegrate
