Synchrotron X-ray topography of lattice undulation of bonded silicon-on-insulator wafers

Lattice undulation of Silicon-on-Insulator (SOI) layers of bonded SOI wafers was observed by synchrotron X-ray topography. Patterns observed on topographs depended on the thickness of the SOI layer, the camera distance between a specimen and an X-ray film. and the diffraction geometry of the Laue and Bragg cases. The dependence was interpreted as the effects of the geometrical relation in reciprocal space among the Ewald sphere, the reciprocal lattice vector, and the surface normal direction. To confirm the origin of the pattern formation, the topographic images were simulated in the framework of the kinematical diffraction theory. Based on the simulation, it was found that a granular pattern observed in the 115 Bragg case was due to the divergence/convergence effect of X-rays diffracted from the undulated SOI layer.