2 Single-Event Effects (SEE) Mechanisms

The primary single-event effect (SEE) event of interest in the THVD9491-SEP is the destructive single-event latch-up. From a risk or impact perspective, the occurrence of an SEL is potentially the most destructive SEE event and the biggest concern for space applications. In mixed technologies such as the linear BiCMOS (LBC9) process used for THVD9491-SEP, the CMOS circuitry introduces a potential SEL susceptibility. SEL can occur if excess current injection caused by the passage of an energetic ion is high enough to trigger the formation of a parasitic cross-coupled PNP and NPN bipolar structure (formed between the p-substrate and n-well and n+ and p+ contacts). The parasitic bipolar structure initiated by a single-event creates a high-conductance path (inducing a steadystate current that is typically orders-of-magnitude higher than the normal operating current) between power and ground that persists (is latched) until power is removed or until the device is destroyed by the high-current state. The process modifications applied for SEL-mitigation were sufficient, as the THVD9491-SEP exhibited no SEL with heavy-ions up to an LET_EFF of 47.5MeV × cm²/mg at a fluence of 1 × 10⁷ions/cm² at a chip temperature of 125°C. The THVD9491-SEP was characterized for SET at a flux of approximately 10⁴ions/cm² × s and a fluence of approximately 10⁶ions/cm² with a die temperature of about 25°C. The device was characterized with two different bias schemes shown below. Under these bias conditions, all recorded VOUT voltage excursions self-recover with no external intervention.