Evaluation using A Noncontact Laser Beam Induced Conductivity/Current Method for the Silicon-on-Insulator made by Wafer Bonding

Abstract

ABSTRACTIn this study, we evaluate the electrical characteristics of the silicon on insulator (SOI) layer made by the wafer bonding method using a photoconductivity modulation method, in other words, noncontact laser beam induced conductivity/current (LBIC) method. The He-Ne laser pulse (λ= 633nm, pulse width=2ms) is used as the carrier-injection light source.The detected signal intensity decreases at the void area as compared with at the center area of the SOI layer where there are no voids. The positions of the voids revealed by the proposed method are in good agreement with those by X-ray topography. We also measure the lifetime using the photoconductivity decay method using the laser diode. The lifetime at the void area is much shorter than that at the center area. It is considered that the decrease in the detected signal intensity at the void area is due to reduction in the minority carrier lifetime.