Characterization and modeling of bonded hydrophobic interfaces for high-power BIMOS-devices

In this paper, a detailed investigation regarding the suitability of silicon-silicon wafer bonding to realize novel high-power thyristor-type devices is presented. The electrical characteristics of the bonding interface are examined both theoretically and experimentally. Moreover, a physical model of the grain boundary in silicon is illustrated and the current flow mechanisms at the potential barrier are explained for unipolar as well as bipolar carrier transport. For bipolar current transport, the relation between minority carrier excess at the bonding interface and the modification of the potential barrier is analytically derived. The different current components at the grain boundary due to thermal emission and carrier recombination are determined. Based on this calculation, a negligible impact of the grain boundary under bipolar current condition, which has been already observed in finite element simulations, is predicted. Finally, experimental results for bonded psn-diode structures are presented further supporting the rapidly decreasing potential barrier at the bonding interface in conductivity modulated devices.