Oxide Electric Field-Induced Degradation of SiC MOSFET for Heavy-Ion Irradiation

This work presents an experimental study of heavy-ion irradiation with different particle linear energy transfer (LET), gate biases, and drain biases. The results reveal that when the irradiation biases are low, the SiC MOSFET does not experience single event effect (SEE) and the electrical properties remain unchanged (the devices are in the safe operating area (SOA)). However, the oxide breakdown voltage of the device is significantly decreased due to the latent damage generated by the irradiation. The experimental results, along with TCAD simulations, suggest that the latent damage induced by the irradiation in the gate oxide is closely related to the peak electric field in the gate oxide at the time of particle incidence. This peak electric field is determined by the potential difference between the two sides of the gate oxide, which is affected by the particle LET, gate biases, and drain biases together. The high potential is determined by the combined effect of the LET and the drain-source voltage. The impact ionization of the particle by the applied electric field causes the accumulation of holes in the JFET oxide, which leads to a decrease in the doping of the N- epitaxial layer and eventually causes a rise in the high potential near the JFET oxide. The low potential is determined by the gate bias, and the negative bias applied to the gate can further increase the potential difference between the two sides of the oxide, causing an increase in the peak electric field in the gate oxide and aggravating the gate oxide damage.