A method of manufacturing a semiconductor device is provided, in which after forming a gate stack and a first spacer thereof, a second spacer and a third spacer are formed; and then an opening is formed between the first spacer and the third spacer by removing the second spacer. The range of the formation for the raised active area 220 is limited by forming an opening 214 between the first spacer 208 and the third spacer 212. The raised active area 220 is formed in the opening 214 in a self-aligned manner, so that a better profile of the raised active area 220 may be achieved and the possible shorts between adjacent devices caused by an unlimited manner may be avoided. Moreover, based on such a manufacturing method, it is easy to make the gate electrode 204 to be flushed with the raised active area 220, and is also easy to implement the dual stress nitride process so as to increase the mobility of the device.