In a method of the present invention during a salicide process, before a second thermal process, a dopant is implanted at a place located in a region ranging from a NixSi layer at meddle height down to a front thereof, or before formation of the NixSi layer, located in a region ranging from a silicon layer at a depth ranging from a half of a predetermined thickness of a NiSi layer down to a depth where is a predetermined front of the NiSi layer. The dopant is allowed to be heated with the NixSi layer together during the second thermal process to form a Si/NiSi2/NiSi interface which may reduce SBH and improve series resistance to obtain a semiconductor device having an excellent performance.