Ion implantation p+/n diodes: post-implantation annealing in a Silane ambient in a cold-wall low pressure CVD reactor

This work reports the realization and characterization of 4H-SiC p+/n diodes with the p+ anodes made by Al+ ion implantation at 400°C and post-implantation annealing in silane ambient in a cold-wall low-pressure CVD reactor. The Al depth profile was almost box shaped with a height of 6×1019 cm-3 and a depth of 160 nm. Implant anneals were performed in the temperature range from 1600°C to 1700°C. As the annealing temperature was increased, the silane flow rate was also increased. This annealing process yields a smooth surface with a roughness of the implanted area of 1.7 - 5.3 nm with increasing annealing temperature. The resistivity of the implanted layer, measured at room temperature, decreased for increasing annealing temperatures with a minimum value of 1.40-cm measured for the sample annealed at 1700°C. Considering only the current-voltage characteristic of a diode that could be modeled as an abrupt p/n junction within the frame of the Shockley theory, the diode process yield and the diode leakage current decreased, respectively, from 93% to 47% and from 2×10-7 Acm-2 to 1×10-8 Acm-2 at 100 V reverse bias, for increasing post implantation annealing temperature.