Currently, SCR (Silicon Controlled Rectifier) is widely used in power electronic devices to convert and control electrical energy.
If a rapidly rising anodic voltage is applied between the anode and the cathode without giving a gate trigger signal, the device is open even if it is much smaller than the breakover voltage under forward-off conditions. This turn-on mode is called dU/dt turn-on or dU/dt failure.
In thyristor fabrication, Al or Ni is used as electrode materials. Unlike the electrode structure of Al elements of p type, the emitter shorts structure was proposed for Ni electrode SCR, but it was not so useful because the emitter shorts effect was not significant and macroscopic shorts structure was found. One of the reasons is that the surface doping concentration of the shunt contact cannot be as high as the emitter region due to the limitation of emitter surface doping concentration when the device is fabricated, and the other is that the Al electrode structure does not suffer from the base-layer ohm contact problems, but the Ni electrode structure does not have ideal ohm contact. Therefore, increasing the p2 region surface doping concentration in a thyristor of Ni electrode structure is very important to improve the forward and reverse blocking voltage symmetry and dU/dt capability.
In order to enhance the cathode emitter shorts effect of SCR of Ni electrode structure, Kim Won Man, a researcher at the Institute of Semiconductor, has proposed a cathode groove etch scheme in which the surface doping concentration in the region p2 can be increased to the emitter region surface doping concentration value, and analyzed the relationship between the dU/dt capability and cathode groove etching structure parameters of the device.
The results show that forward and reverse blocking voltage symmetry is within 5% and the critical forward blocking voltage rise rate dU/dt is improved by 1.5 times.
His study results can be applied to power thyristors including TRIAC (Bidirectional Thyristor) with Ni electrodes and GTO (Gate-Turn-0ff Thyristor).