Semi-super junction SiGe high voltage fast and soft recovery switching diodes

Abstract

Semi-super junction (S-SJ) is developed on the basis of the super junction (SJ) structure by adding BAL (bottom assist layer) in the base region. One should only adjust the depth and the doping concentration of the BAL in the S-SJ structure to obtain higher working voltages. At the same on resistance, the aspect ratio of p-column in the S-SJ structure is less than that in the super junction structure, which means simpler process of epitaxial growth and ion implantation, which is very effective in reducing the process difficulty and the manufacture cost. Because the band gap of SiGe material can be adjusted by changing the Gefraction and the epilayers strain, the carrier mobility is increased with the increasing Ge content, the manufacture process is compatible with Si process, and great importance has been gradually attached to the SiGe material. To meet the requirements of low forward conducting voltage drop, high breakdown voltage, minimum reverse leakage current, and fast and soft reverse recovery process for power diodes in high frequency power electronics circuits, a S-SJ SiGe diode with remarkable improvement in all these characteristics of present power diode is proposed by combining both merits of S-SJ structure and SiGe material in this paper.