Design and Simulation of 1.2kV Semi-Super Junction FRD with Vertical Variation Doping

A 1200V vertical variable doped semi-super junction fast recovery diode (VVD-Semi-SJ-FRD) is presented in this paper. In super junction structure, P-pillar and drift region are needed to maintain charge balance. As a result, the reverse breakdown voltage of the semi-super junction fast recovery diode is very sensitive to the doping concentration of P-pillar, resulting in a narrow process window for ion implantation of P-pillar. The structure proposed in this paper uses three epitaxial layers, the epitaxial layer near the side of the P-type region and the epitaxial layer below the P-pillar is low-doping, and the middle is high-doping. By analyzing the influence of P-pillar concentration on reverse breakdown voltage and the electric field distribution at different concentrations, it is shown that the proposed structure can effectively reduce the sensitivity of reverse breakdown voltage to P-pillar doping concentration, thus enlarges the process window of P-pillar ion implantation.