Characterization of SOI wafers by synchrotron X-ray topography

Synchrotron X-ray topographs were taken for bonded silicon-on-insulator wafers. Under the grazing incident condition, the topographs of the top Si layer and the substrate are similar, which represent the variation in incident angle due to surface undulation. Furthermore, a circular concentric pattern was observed in the topographs of the top Si layer both at the grazing and higher incident angles. This shows that the concentric pattern is not due to surface undulation, but due to lattice distortion.