Study of SiO2 encapsulation for aluminum and phosphorus implant activation in 4H-SiC

SiO2 encapsulation layer was studied for aluminum (Al) and phosphorus (P) implant activation anneal in 4H-SiC. Both Al- and P+ implantation were carried out at 650 °C followed by activation anneal at 1400 °C to 1500 °C. X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and four-point-probe (FPP) measurements were performed to examine surface stoichiometry, roughness, and sheet resistance of the implanted SiC regions. The effect of using SiO2 encapsulation layer for Al implant activation on the performance of 4H-SiC p-i-n diodes with both p-type active region and JTE region formed by Al implantation was also investigated. Forward and reverse characteristics including saturation current density J0, ideality factor η, reverser leakage current density JL and threshold breakdown voltage VBR have been extracted. The results show that SiO2 encapsulation effectively protects the SiC surface during high temperature implant activation for both Al- and P+.