Improvement in breakdown voltage characteristics of SiC Schottky barrier diode by incorporating a guard ring-assisted field limiting ring and an internal ring

Abstract

We investigate the width, spacing, and number dependencies of an Al +-implanted field limiting ring (FLR) and the influence of an Al +-implanted internal ring on the breakdown voltage characteristics of a silicon carbide (SiC) Schottky barrier diode (SBD). SiC-SBDs having an Al +-implanted guard ring-assisted FLR surrounding a Schottky contact edge and an internal ring inside a Schottky contact were fabricated via ion implantation, annealing, photolithography, and metal lift-off techniques. The breakdown voltage characteristics of the SiC-SBD are enhanced by incorporation of the guard ring-assisted FLR at the Schottky contact edge and the internal ring at Schottky contact region. The breakdown voltage characteristics of the guard ring-assisted FLR SiC-SBDs with an internal ring are significantly dependent on the width, spacing, and number of FLRs. The breakdown voltage is improved as either the FLR width and FLR number increase or the FLR spacing decreases. 1650 V maximal breakdown voltage, corresponding to 82% ideal breakdown voltage, is observed with seven FLRs having 5 μm width and 1 μm spacing. The results indicate that a greater number of FLRs, as well as increased FLR width and decreased spacing can effectively suppress electric field crowding at the periphery of the Schottky contact edge, resulting in higher breakdown voltage. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA.