Stacking Fault Knocking-Down by High-Energy Ion Implantation (SF-KHII™) Method to Fabricate Reliable SiC Devices

Silicon carbide (SiC) devices are becoming popular as power semiconductor devices for inverter drive in electric railway vehicles and electric cars. In recent years, SiC devices have been installed in the Shinkansen train N700S, which began operation in 2020. However, SiC devices are more expensive than silicon (Si) devices, so their introduction into hybrid vehicles with internal combustion engines and electric vehicles is still difficult. There are several factors that make SiC devices expensive, but one of them is the lack of increase in the manufacturing yield of devices with long-term operational reliability. One phenomenon that impedes the long-term operational reliability of SiC devices is called bipolar degradation. Bipolar degradation occurs when electron-hole pairs are injected from a p-n junction inside a SiC device and recombine at basal plane dislocations (BPDs) in the 4H-SiC crystal, causing stacking faults (SFs) to expand. The expanded SFs bring electrical resistance components inside the device and become a source of leakage current, degrading the performance of SiC devices. This degradation is difficult to detect in the early stages of device operation, and therefore not only reduces manufacturing yields but also increases the cost of reliability testing. Therefore, methods to suppress this bipolar degradation have been discussed for many years. Recently, we have developed a new method called stacking fault knocking-down by high-energy ion implantation (SF-KHII™) to suppress the bipolar degradation [1]–[7], and this paper introduces the outline of this method.