Reliability Concern on Extended E-SOA of SOI Power Devices With P-Sink Structures

The P-sink structure is widely used in silicon-on-insulator (SOI) power devices (SOI-LIGBT and SOI-LDMOS) to extend the electrical safe operating area (E-SOA) as it can suppress the trigger of the parasitic transistor. In this paper, the electrical behavior and reliability issues in the extended E-SOA for 200-V SOI power devices with P-sink structures are investigated for the first time. For SOI-LIGBT, the normal I-V curve and small hot-carrier-induced degradation are observed in the extended E-SOA; thereby, the P-sink structure plays a good role. However, for SOI-LDMOS, two mechanisms dominate the electrical behavior in the extended E-SOA so as to bring the unusual “hump” in the I- V curve; meanwhile, it results in serious hot-carrier-induced degradation, reducing the lifetime of the device in practical applications. As a result, the P-sink structure is not the best choice to extend the E-SOA of SOI-LDMOS.