Silicided shallow p+n junctions formed by BF2+ implantation into thin Co films on Si substrates to a low dosage (5 × 1014 cm-1) and subsequent rapid thermal annealing (RTA) or conventional furnace annealing (CFA) are used to show the impact of silicides on junction characteristics. CFA results in a lower leakage than RTA at a low bias as 5 V at high temperatures attributable to longer annealing time. All the diodes made by RTA exhibit a hard-breakdown behavior. For CFA 700°C annealing, however, an anomalously poor reverse I-V behavior indicative of athermal emission is found at high bias. In addition, the 800°C-formed diodes and the CFA-treated 1 × 1016 cm-2 implanted samples show good reverse characteristics even at high bias. As a result, annealing conditions should be properly chosen to reduce the impact of silicides on shallow junctions.