A process consideration for forming silicided shallow junctions, arising from silicidation process, has been discussed. The CoSi2 shallow p + n junctions formed by various schemes are characterized. The scheme that implants BFÂ‡ ions into thin Co films on Si substrates and subsequent silicidation yields good junctions, but the problems about the dopant drive-in and knock- on of metal deeply degrade this scheme. In the regime that implants the dopant into Si and then Co deposition, however, a large perimeter leakage of 0.1 nA/cm is caused. Generation current, associated with a defect-enhanced diffusion of Co in Si during silicidation, dominates the leakage. A high-temperature pre-activation prior to Co deposition reduces the perimeter leakage to 0.038 nA/cm but which deepens the junctions.