Semiconductor fabrication method and structure using multiple sacrificial layers to form sidewall spacers

Semiconductor devices fabrication method is provided. The method for fabricating the semiconductor device includes: providing a semiconductor substrate; forming a gate structure on a surface of the semiconductor substrate; forming protective sidewall spacers on sidewall surfaces of the gate structure and to cover sidewall surfaces of the gate dielectric layer; forming sacrificial sidewall spacers on sidewall surfaces of the protective sidewall spacers and between the protective sidewall spacers and the gate structure; forming a first dielectric layer on the surface of the semiconductor substrate around the gate structure, the protective sidewall spacers and the sacrificial sidewall spacers; forming conductive plugs in the first dielectric layer at opposite sides of the gate structure, the protective sidewall spacers and the sacrificial sidewall spacers; and removing the sacrificial sidewall spacers to form air gap spacers between the protective sidewall spacers and the conductive plugs.