Method of manufacturing a semiconductor device and a semiconductor device

A method of manufacturing a semiconductor device, comprising:

• forming a fin structure over a semiconductor substrate in which first semiconductor layers A, second semiconductor layers B, and third semiconductor layers C are stacked in a repeating sequence ABAC,
• wherein the first semiconductor, second semiconductor, and third semiconductor layers comprise different materials;
• forming a sacrificial gate structure defining a gate region over the fin structure;
• removing the third semiconductor layers from source/drain regions of the fin structure, which are not covered by the sacrificial gate structure;
• forming source/drain epitaxial layers in the source/drain regions;
• removing the sacrificial gate structure;
• removing the third semiconductor layers from the gate region;
• and
• forming a gate electrode structure in the gate region, wherein the gate electrode structure wraps around the first and second semiconductor layers.

A semiconductor device comprising:

• at least one semiconductor nanowire disposed over a semiconductor substrate;
• a gate structure wrapping around the at least one semiconductor nanowire;
• and
• source/drain structures disposed over the semiconductor substrate on opposing sides of the gate structure,
• wherein the at least one semiconductor nanowire comprises two opposing layers composed of a first semiconductor material sandwiching a layer of a second semiconductor material different from the first semiconductor material.