Semiconductor device and fabrication method

A semiconductor device, comprising:

• a semiconductor substrate;
• a gate structure including a gate dielectric layer formed on a surface of the semiconductor substrate, wherein sidewall surfaces of the gate structure includes a first sidewall surface region and a second sidewall surface region above the first sidewall surface region;
• first sidewall spacers formed on the first sidewall surface region of the gate structure and covering sidewall surfaces of the gate dielectric layer;
• a first dielectric layer formed on the surface of the semiconductor substrate around the gate structure and the first sidewall spacers;
• conductive plugs formed in the first dielectric layer at both sides of the gate structure and the first sidewall spacers;
• and
• air gap spacers formed between the second sidewall surface region and the conductive plugs and above the first sidewall spacers.

A method for fabricating a semiconductor device, comprising:

• providing a semiconductor substrate;
• forming at least one gate structure on a surface of the semiconductor substrate, wherein the gate structure includes a gate dielectric layer formed on the 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, wherein the sacrificial sidewall spacers and the protective sidewall spacers are made of different materials;
• forming a first dielectric layer on the surface 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 both 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.