Structural characterization of a bonded silicon-on-insulator layer with voids by micro-Raman spectroscopy

Crystalline quality in a void region of a bonded silicon‐on‐insulator (SOI) wafer is evaluated by micro‐Raman spectroscopy. Downshifting and broadening of the Si optical‐phonon peak are observed at the edge of the void, while spectra within the void are little different from those outside the void. Comparison with calculated results based on the theory of the phonon localization shows that both the shift and the broadening are mainly due to structural disorder and not strain. Electrical properties in a void region are also evaluated by a laser‐microwave method. The lifetime of excess carriers has its minimum value at the void edge. Those results consistently show that the SOI layer is deformed plastically rather than elastically at the boundary of the void