White beam synchrotron topographic characterisation of silicon wafers directly bonded by oxide layer

Various types of layer structures obtained by direct bonding of oxidised si licon wafers were studied by means of different X-ray topographic methods u sing white synchrotron beam and the observation of selective etching patter n using scanning electron microscopy and optical microscopy with Nomarski c ontrast. In the present investigation the particularly important results we re obtained with synchrotron section topography, which revealed different d efects caused by bonding of thick wafers, in particular the dislocations an d microcracks. The different situation was observed in the case of bonding with a very thin layer separated from a silicon substrate by high dose prot on implantation. In this case a thin layer accommodated practically all ind uced strain and the bonded oxidised thick substrate remained defect-free in its inner volume.