Double-implanted 4H-SiC superjunction UMOSFET without bipolar degradation

Abstract We demonstrated trench-gate 4H-SiC superjunction MOSFET (SJUMOS) without bipolar degradation using a double implantation process with a multi-epitaxial method. A conventional SJUMOS with a single implantation of aluminum ions can suppress bipolar degradation at the current stress below 1000 A cm −2 because the carrier lifetime of the 4H-SiC epitaxial film is shortened by the damage generated during aluminum ions implantation for p-column formation. To further suppress the bipolar degradation at above 1500 A cm −2 , this study developed SJUMOS with the double implantation process. The n-column was formed by low doping density epitaxial growth and additional phosphorus ions implantation, and the p-column was formed by aluminum ions implantation. The double-implanted SJUMOS showed a forward voltage shift of the body diode below 0.5% after a current stress of 1500 A cm −2 . This was because the additional damage from phosphorus ions implantation further shortened the carrier lifetime of 4H-SiC epitaxial film, and this resulted in stable forward voltage.