Observation of Lattice Undulation of Commercial Bonded Silicon-On-Insulator Wafers by Synchrotron X-Ray Topography.

Synchrotron X-ray topographs of silicon-on-insulator (SOI) layers of two kinds of commercial bonded SOI wafers were obtained; one is fabricated by transferring an epitaxial layer over porous Si, and the other is processed using hydrogen-delamination-induced splitting. For the 2-µm-thick SOI layer of the former wafer, the quasi-periodical contrasts were observed in the topographs, which indicate that the lattice plane of the SOI layer undulated at spatial intervals of about 20 µm with a tilt angle of the order of ten arc seconds. It was also evident from the granular pattern in the topographs that the undulation existed in the SOI layer of 100 nm thickness for both of the wafers.