A method for manufacturing a semiconductor device is disclosed, comprising: providing a substrate, a gate region on the substrate and a semiconductor region at both sides of the gate region; forming sacrificial spacers, which cover a portion of the semiconductor region, on sidewalls of the gate region; forming a metal layer on a portion of the semiconductor region outside the sacrificial spacers and on the gate region; removing the sacrificial spacers; performing annealing so that the metal layer reacts with the semiconductor region to form a metal-semiconductor compound layer on the semiconductor region; and removing unreacted metal layer. By separating the metal layer from the channel and the gate region of the device with the thickness of the sacrificial spacers, the effect of metal layer diffusion on the channel and the gate region is reduced and performance of the device is improved.