Disclosed is a method of manufacturing a semiconductor device. First, a silicidation blocking layer is formed on a semiconductor substrate by a plasma enhanced chemical vapor deposition process. Next, the silicidation blocking layer in a region in which a metal silicide contact is to be formed is removed by a wet etching process. Next, after a metal layer is formed on the resultant, the silicon in the region and the metal of the metal layer are reacted to form the metal silicide. Since the silicidation blocking layer consisting of PE-SiON is formed at a low temperature of less than 400 Celsius Degrees, it is possible to prevent diffusion and redistribution of impurities in gate and source/drain regions of a transistor during the deposition of the silicidation blocking layer.