A method for manufacturing a semiconductor structure includes providing an n-type field effect transistor comprising a source region, a drain region, and a first gate; forming a tensile stress layer on the n-type field effect transistor; removing the first gate so as to form a gate opening; performing an anneal so that the source region and the drain region memorize a stress induced by the tensile stress layer; forming a second gate; removing the tensile stress layer; and forming an interlayer dielectric layer on the n-type field effect transistor. A replacement process is combined with a stress memorization technique for enhancing the stress memorization effect and increasing mobility of electrons, which in turn improves overall properties of the semiconductor structure.