Electrical-thermal-stress coupled-field effect in SOI and partial SOI lateral power diode

The requirement of electrical-thermal-stress (E-T-S) modeling of semiconductor devices, as indicated by ITRS2006, demands the use of finite-element analysis (FEA) for device simulation. In this study, we perform E-T-S coupled-field simulation from the first principle by considering the stress-induced modification of the Si band structures, and employ the FEA software COMSOL to apply the E-T-S model to the study of lateral power diodes as an example. This power diode is a basic building block for power electronic devices and circuits, and as a first attempt for the ETS model application, only the steady-state characteristics of the lateral power diodes are considered. Simulations are performed on two types of diodes, namely, silicon-on-insulator (SOI) and partial SOI (PSOI) lateral power diodes because the temperature and mechanical stress distributions are very different in these diodes even under the same operating conditions. From the comparison of the computational results of SOI and PSOI diodes, the results indicate that PSOI power diode structure enables efficient heat conduction from the hot junctions and offers higher breakdown voltage. However, it has larger reverse current, higher thermomechanical stress that can lead to reliability issues.