Method of manufacturing a semiconductor device

In a method of manufacturing a semiconductor device, a fin structure in which first semiconductor layers and second semiconductor layers are alternately stacked is formed, a sacrificial gate structure is formed over the fin structure, a source/drain region of the fin structure, which is not covered by the sacrificial gate structure, is etched thereby forming a source/drain space, a stressor layer is formed in the source/drain space, a metal gate structure including part of the second semiconductor layer as channel regions is formed by a gate replacement process, after the metal gate structure is formed, the stressor layer is at least partially removed, and a source/drain contact comprising metal or a metallic material is formed in the source/drain space from which the stressor layer is at least partially removed.