2 SEE Mechanisms

The primary SEE events of interest in the TMP461-SP are single-event latch-up (SEL), single-event burn-out (SEB), and single-event transient (SET). From a risk and impact point-of-view, the occurrence of an SEL and SEB is potentially the most destructive SEE event and the biggest concern for space applications. In mixed technologies such as the LBC8LV process used for the TMP461-SP, the CMOS circuitry introduces a potential for SEL and SEB 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-sub and n-well and n+ and p+ contacts). The parasitic bipolar structure initiated by a single-event creates a high-conductance path (inducing a steady-state current that is typically orders-of-magnitude higher than the normal operating current) between power and ground that persists (and 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 TMP461-SP exhibited no SEL with heavy ions up to an LET_EFF of 76.18 MeV-cm²/mg at a fluence of 10⁷ ions/cm² and a chip temperature of 125°C.

This study was performed to evaluate the cross section and transient effects with a bias voltage of 3.6 V and 2.5 V. To capture different SET signature events, the trigger was set with ±2° variance. Heavy ions with LET_EFF 65.65 MeV-cm²/mg were used to irradiate the devices. Flux of 10⁵ ions/s-cm² and fluence of 10⁷ ions/cm² were used during the exposure at room temperature. The output temperature data was processed and analyzed.

Figure 2-1 Functional Block Diagram of the TMP461-SP