Characterization of bond and etch-back silicon-on-insulator wafers by photoluminescence under ultraviolet excitation

Abstract

Photoluminescence (PL) spectroscopy under the ultraviolet (UV) light excitation has been used for the characterization of bond and etch-back silicon-on-insulator (BESOI) wafers. Since the UV light can excite only the silicon-on-insulator (SOI) layer and the SOI structure prevents the photoexcited carriers from diffusing into the base wafer, the PL light is emitted only from the SOI layer. We have detected defects induced during the photoassisted chemical etching process in BESOI wafers. The defect-related emission disappears and the electron-hole droplet signal appears after annealing at 800 °C for 30 min. This allows us to suggest that the annealed SOI layer is comparable in crystalline quality with that of conventional bulk Si wafers and that the recombination velocity at the interfaces is low.