Schottky barrier diodes are fabricated on silicon surfaces whose impurity concentrations are controlled by ion implantation techniques. The barriers are produced by PtSi or Al‐Si. The forward characteristics of the diodes show that the forward voltages of Schottky barrier diodes made by PtSi are lower than those made by Al‐Si for implanted doses of 2×1013cm−2and higher. Spreading resistance measurements show that the implanted phosphorus atoms are piled up near the PtSi‐Si interface during PtSi formation. This phenomenon causes reduction of the effective barrier height.