Fin field effect transistor fabrication and devices having inverted t-shaped gate

A method of forming a fin field effect transistor (finFET), comprising:

• forming a sacrificial gate layer on a vertical fin, wherein the sacrificial gate layer has a thickness in a range of about 7 nm to about 15 nm;
• forming two gate spacer layers on the sacrificial gate layer, wherein the two gate spacer layers each have a thickness in the range of about 1.5 nm to about 3 nm, and wherein each gate spacer layer covers a portion of the sacrificial gate layer;
• removing an exposed portion of the sacrificial gate layer not between the sacrificial gate layers;
• forming a source/drain spacer layer on the outward-facing sidewall of each gate spacer layer and the outward-facing sidewalls of a remaining portion of the sacrificial gate layer, wherein a segment of the sacrificial gate layer is between the two source/drain spacer layers;
• removing the segment of the sacrificial gate layer between the two source/drain spacer layers to form a recessed cavity in each gate spacer layer that exposes an inward facing sidewall of each of the source/drain spacer layers, wherein the recessed cavity in each gate spacer layer has a depth equal to the thickness of the gate spacer layer.

A method of forming a fin field effect transistor (finFET) having an inverted-T gate, comprising;

• forming a sacrificial gate layer on a vertical fin on a substrate;
• forming a dummy gate layer on at least a portion of the sacrificial gate layer;
• forming a gate spacer layer on opposite sidewalls of the dummy gate layer;
• removing at least a portion of the sacrificial gate layer not covered by the dummy gate layer and gate spacer layers;
• forming a source/drain spacer layer on each of the outward-facing sidewalls of the gate spacer layers and the outward-facing sidewalls of the sacrificial gate layer, wherein a segment of the sacrificial gate layer is between the two source/drain spacer layers;
• removing the dummy gate layer to expose the inward-facing sidewalls of the gate spacer layers and the portion of the sacrificial gate layer between the gate spacer layers;
• and
• removing the segment of the sacrificial gate layer between the two source/drain spacer layers to form a plurality of recessed cavities.