PHOTOLUMINESCENCE SPECTROSCOPY OF DIRECT-BONDED SILICA-BASED WAFERS

We report results of an original photoinduced luminescence spectroscop y application to determine the process of direct bonding of silica waf ers. This application is based upon laser induced visible fluorescence of the defects created during the bonding process and can also be use d in the cases when neither electron microscopy nor optical near field analysis permit a junction observation. The results are related to tw o different assemblies: first we consider two pyrex glass wafers assem bled by direct wafer bonding technology and second we applied the same technology to two ion-exchanged wafers to obtain buried planar wavegu ide. The bonding process induces for both assemblies on the one hand a n enhancement of emitting defects at 570 nm which are present in the b lank wafer material and create on the other hand new defects emitting at 525 nm. (C) 1997 Elsevier Science B.V.