2 SEE Mechanisms

The primary single-event effect (SEE) event of interest in the INA950-SEP is the destructive single-event latch-up (SEL). From a risk and impact point-of-view, 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 (LBCSOI2) process used for INA950 -SEP, the CMOS circuitry introduces a potential for 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-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 (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 INA950-SEP exhibited no SEL with heavy-ions up to a of LETEFF = 50.4MeV× cm² / mg at a fluence up to 1.0 × 10⁷ ions / cm² and a chip temperature of 125°C.

This study was performed to evaluate the SEL effects with a bias voltage of 5.5V on Vs. Heavy ions with LETEFF = 50.4MeV × cm² / mg were used to irradiate the devices. Flux of 1 × 10⁵ ions / s-cm² and fluence up to 1.0 × 10⁷ ions / cm²were used during the exposure at 125°C temperature.

Figure 2-1 shows a functional block diagram for this device.