Fin-based semiconductor device structure including self-aligned contacts and method for forming the same

A semiconductor device structure, comprising:

• a fin structure formed over a substrate, wherein the fin structure comprises a plurality of nanostructures;
• a gate structure formed over the nanostructures, wherein the gate structure comprises:
• a gate dielectric layer formed over the nanostructures;
• a first conductive layer formed over the gate dielectric layer, wherein a topmost surface of the first conductive layer is lower than a top surface of the gate dielectric layer;
• a fill layer formed over the first conductive layer;
• and
• a protection layer formed over the fill layer, wherein the protection layer is a conductive layer;
• and
• a gate spacer layer formed adjacent to the gate structure, wherein an outer sidewall surface of the gate spacer layer extends beyond a sidewall surface of the protection layer.

A method for forming a semiconductor device structure, comprising:

• forming a fin structure over a substrate;
• forming a dummy gate structure over the fin structure;
• forming a dielectric layer over the dummy gate structure;
• forming a gate spacer layer adjacent to the dummy gate structure;
• removing the dummy gate structure to form a trench in the dielectric layer;
• forming a gate dielectric layer in the trench;
• forming a first layer over the gate dielectric layer, wherein a top surface of the first layer is lower than a top surface of the gate spacer layer;
• forming a fill layer over the first layer;
• forming a protection layer over the fill layer;
• and
• forming an insulating layer on the protection layer, wherein a top surface and sidewall surfaces of the protection layer are covered by the insulating layer, and a portion of the insulating layer is in direct contact with the gate spacer layer.