Non-Simultaneous Triggering Induced Failure of CS-MCT Under Repetitive High-Current Pulse Condition

This work demonstrates the failure mechanism of the cathode-short MOS controlled thyristor (CS-MCT) under repetitive high-current pulse condition. It is found that the hot spot and burn-out point localized at the boundary between the active area and terminal region. This is due to the premature triggering of the edge cells compared to the inner cells, which results in the non-uniform distribution of pulse current, consequently destroying the device. Furthermore, it is testified that this failure mode of non-simultaneous triggering will be more severe for the device with large gate parasitic resistance. The mixed-mode 3D TCAD simulations with electro-thermal model were carried out to give an insight of this failure mechanism. The simulation and analysis results were confirmed by experiment results, such as infrared thermography, EMMI, and SEM. Next, an effective approach was proposed to avoid this failure. Finally, the device achieves over 3000 pulses at current more than 5200A without any degradation detected.