Triggering Mechanism for Neutron Induced Single-Event Burnout in Power Devices

Abstract

Cosmic ray neutrons can trigger catastrophic failures in power devices. It has been reported that parasitic transistor action causes single-event burnout (SEB) in power metal–oxide–semiconductor field-effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs). However, power diodes do not have an inherent parasitic transistor. In this paper, we describe the mechanism triggering SEB in power diodes for the first time using transient device simulation. Initially, generated electron–hole pairs created by incident recoil ions generate transient current, which increases the electron density in the vicinity of the n-/n+ boundary. The space charge effect of the carriers leads to an increase in the strength of the electric field at the n-/n+ boundary. Finally, the onset of impact ionization at the n-/n+ boundary can trigger SEB. Furthermore, this failure is closely related to diode secondary breakdown. It was clarified that the impact ionization at the n-/n+ boundary is a key point of the mechanism triggering SEB in power devices.

Observation and Analysis of Neutron-Induced Single-Event Burnout in Silicon Power Diodes

“…The temporary decrease in the current just before 1 × 10 −9 s shown in Fig. 3 is caused by a decrease in the impact ionization rate at the n − /n + interface, when the peak electric field shifts to deep within the n + diffusion region [19], [20]. Finally, the current again increases due to impact ionization deep within the n + diffusion region.…”

“…3 from 0 to 2.55 × 10 −9 s. In addition, the potential distribution adopts a funnel-like shape during the SEB [19], [20]. The heat generation depth c is 150 μm in light of the potential deformation during the SEB shown in Fig.…”

“…2 shows the chip failure rate as a function of the applied voltage for Si power devices. The failure rate is seen to increase sharply at a particular voltage, which is defined as the SEB threshold voltage [20]. Transient 0885-8993 © 2014 IEEE.…”

“…Transient thermal simulations have been used to investigate the behavior of electron-hole pairs generated along the ion tracks in power devices under the influence of the applied voltage. The electrostatic potential adopts a funnel-like shape and the highly localized current results in an increase in the electron density in the vicinity of the n − drift region/n + diffusion region interface [16], [18]- [20], [22]. This space charge effect leads to a shift of the peak electric field from the p − body region/n − drift region interface to the n − drift region/n + diffusion region interface.…”

“…It was clarified that the SEB mechanism in power diodes is thermal failure caused by local secondary breakdown. Moreover, it was shown to be possible to control the SEB threshold voltage by optimal choice of device parameters such as the drift region thickness [16]- [20].…”