Abstract:

To analyze the failure mechanisms of the silicon carbide field-effect transistor (SiC MOSFET) and silicon field-effect transistor (Si MOSFET) under the short-circuit condition, numerical models for the silicon carbide field-effect transistor and silicon field-effect transistor have been built by technology computer aided design (TCAD), which can replicate the short-circuit failure of the silicon carbide field-effect transistor and silicon field-effect transistor. In the numerical models, the self-heating effect has been introduced to simulate the temperature change and thermal transmission inside the device, and the Fowler-Nordheim tunneling effect and Poole-Frenkel emission simulate the leakage current of the gate oxide. Experimental results have verified the numerical models. With the numerical models, the change of the gate driving voltage, the distribution of current flowlines and the temperature inside the two devices have been compared. The results have shown that the short-circuit failure of the silicon carbide field-effect transistor originates from the metal melting of the gate surface electrode and serious oxide degradation. By contrast, the short-circuit failure for the silicon field-effect transistor comes from the triggering of the parasitic bipolar transistor. As a result, the leakage current inside the silicon field-effect transistor is out of control, which leads to the catastrophic damage.

Key words: silicon carbide, field-effect transistor, short-circuit failure, parasitic bipolar transistor, degradation