The present invention discloses a method for manufacturing a semiconductor device, comprising: forming a gate stacked structure on a substrate; forming a source/drain region and a gate sidewall spacer at both sides of the gate stacked structure; depositing a Nickel-based metal layer at least in the source/drain region; performing a first annealing so that the silicon in the source/drain region reacts with the Nickel-based metal layer to form a Ni-rich phase of metal silicide; performing an ion implantation by implanting doping ions into the Ni-rich phase of metal silicide; performing a second annealing so that the Ni-rich phase metal silicide is transformed into a Nickel-based metal silicide, and meanwhile, forming a segregation region of the doping ions at an interface between the Nickel-based metal silicide and the source/drain region. The method according to the present invention performs the annealing after implanting the doping ions into the Ni-rich phase of metal silicide, thereby improving the solid solubility of the doping ions and forming a segregation region of highly concentrated doping ions, thus the SBH of the metal-semiconductor contact between the Nickel-based metal silica and the source/drain region is effectively reduced, the contact resistance is decreased, and the driving capability of the device is improved.