Formation of Deep pn Junctions by High-Energy Al and B Ion Implantations into SiC

Abstract

High-energy (MeV) implantation of Al⁺ and B⁺ into SiC epilayers has been investigated. A 3μm-deep pn junction is formed by room-temperature multiple Al⁺ or B⁺ implantation with implantation energies up to 6.2MeV or 3.4MeV, respectively. Rutherford backscattering channeling measurements have revealed that implantation-induced damages can be reduced close to a virgin level by high-temperature annealing at 1700_??_1800°. High electrical activation ratios over 90% have been achieved for both Al⁺- and B⁺-implanted layers by annealing at 1800°. Mesa pn diodes with a 15μm-thick n-layers formed by MeV implantation have exhibited high breakdown voltages of 2860_??_3080V. The reverse characteristics of the diodes have been substantially improved by increasing annealing temperature up to 1800°. The diode performance is discussed with the results of deep level analyses near the junctions.