| Power electronic devices are widely used in space-borne and military applications. Power MOSFETs, however are vulnerable to catastrophic failures that can be triggered when a single energetic particle, such as heavy proton and ion, passes through the device structure. Single-event burnout (SEB) and single-event gate rupture (SEGR) are two common failure mechanisms that are triggered by a single particle. The failure mechanisms and the role that device structure parameters play on radiation hardening are investigated in this paper.First, the structure and process of VDMOS is introducted. Operating characteristics are discussed under the on and off state of VDMOS. The threshold voltage, transconductance, on-resistance, and breakdown voltage of VDMOS are discussed.Second, analytical model and 2-D simulation model of SEB are discussed. Analytical model focuses on avalanche multiplication effect and the turn-on of the parasitic BJT. Current response> position effect and the SEB safe work area are investigated with the help of MEDICI. Besides, the relationship between device structure parameters and the burnout threshold is discussed depending on both analytical model and 2-D simulation model of SEB.Third, analytical, semianalytical and simulation models have been developed to explain the process of SEGR. A new concept which is called "pool of holes" is put forward to explain the collection of holes at the Si-SiO2 interface. It also indicates that size of JFET plays an important role in SEGR sensitivity. Micro-breakdown of gate oxide is put forward according to the drain current response after radiation. It has shown that the sensitivity of SEGR and the sensitivity of SEB depend on each other.At last, a 150V radiation hardened VDMOS which is compatible with existing process conditions is designed. Radiation resistance of new device structures including super junction?trench and PSOI is evaluated which provides theoretical basis for the application of these devices in aerospace. |
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