Influence of Negative Bias Temperature Instability on Single-Event Burnout in n-Channel Power VDMOS Transistors

Abstract

This article investigates the effects of cumulative damage, specifically negative bias temperature instability (NBTI), on the transient phenomenon known as single-event burnout (SEB) in power vertical diffused metal-oxide–semiconductor field-effect transistors (VDMOSFETs). Tantalum heavy ion irradiation (THII) experiments were conducted on devices subjected to various pretreatments: negative bias temperature stress (NBTS), hydrogen, low temperature, and a combination of hydrogen and NBTS. The results indicate that devices pretreated with NBTS exhibit increased sensitivity to SEB, whereas those subjected to other pretreatment methods demonstrate decreased sensitivity. In addition, the subthreshold mid-gap technique (SMGT) was employed to differentiate between interface traps and oxide charges, with subsequent technology computer-aided design (TCAD) simulations analyzing their impacts on SEB. The findings reveal that NBTS pretreatment primarily reduces the built-in potential ( $\varphi _{\text {B}}$ ) of parasitic bipolar junction transistor (BJT) conduction by generating oxide charges, thereby increasing SEB sensitivity. Conversely, pretreatments with hydrogen and low temperature promote the conversion of oxide charges into interface traps, resulting in decreased SEB sensitivity. Although the change in SEB sensitivity is relatively small, this research reveals a synergistic interaction between NBTI and SEB, which may lead to premature SEB occurrences and reduce the operational lifespan of power VDMOS transistors.