A multiple-floating-zone-assisted graded-step-JTE for high-voltage 4H-SiC GTO thyristor

In this work, a multiple-floating-zone-assisted graded-step junction termination extension (MAGS-JTE) is proposed for 4H-silicon carbide (SiC) GTO thyristor. The MAGS-JTE combines the advantages of two-steps JTE (TS-JTE) and multiple-floating-zone JTE (MFZ-JTE), and gradual doping profile is formed by varying the implantation dose of each zone, which is effective to suppress the electric field crowding in termination region and widen the JTE dose window. The fabricated SiC GTO with 60 mu m drift layer achieves an ultra-high breakdown voltage of 9.3 kV by adopting the MAGS-JTE, reaching about 93% of the theoretical value of 10 kV. The yield of over 6 kV SiC GTO in 4'' wafer is about 78% with chip size of 6.9 mm x 6.9 mm, which shows that the MAGS-JTE structure is well suited for high-voltage device applications.

Automated summary

A multiple-floating-zone-assisted graded-step junction termination extension (MAGS-JTE) is proposed for 4H-silicon carbide (SiC) GTO thyristor, which combines the advantages of two-steps JTE (TS-JTE) and multiple-floating-zone JTE (MFZ-JTE). By varying the implantation dose of each zone, the MAGS-JTE forms a gradual doping profile that effectively suppresses electric field crowding and widens the JTE dose window. The fabricated SiC GTO achieves an ultra-high breakdown voltage of 9.3 kV, reaching about 93% of the theoretical value of 10 kV. The MAGS-JTE structure shows great potential for high-voltage device applications.