White Beam Synchrotron Topographic Characterisation of Silicon Wafers Directly Bonded by Oxide Layer

Various types of layer structures obtained by direct bonding of oxidised silicon wafers were studied by means of different X-ray topographic methods using white synchrotron beam and the observation of selective etching pattern using scanning electron microscopy and optical microscopy with Nomarski contrast. In the present investigation the particularly important results were obtained with synchrotron section topography, which revealed different defects caused by bonding of thick wafers, in particular the dislocations and microcracks. The different situation was observed in the case of bonding with a very thin layer separated from a silicon substrate by high dose proton implantation. In this case a thin layer accommodated practically all induced strain and the bonded oxidised thick substrate remained defect-free in its inner volume.