Fin field effect transistor (FinFET)

A fin field effect transistor (FinFET), comprising:

• a substrate;
• a first trench defining a first gate over the substrate, the first trench being filled with metallic material and comprising top and bottom portions of different widths;
• a second trench defining a second gate over the substrate, the second trench being filled with the metallic material and comprising top and bottom portions of different widths, wherein each of the first and second trenches further comprises a middle portion (i) disposed between the top and bottom portions of the respective first and second trenches, and (ii) having a tapered profile that continuously narrows in a direction from the top portions to the bottom portions;
• first spacer material disposed adjacent to lateral sides of the first trench, the first spacer material having a first height on a first side that is equal to a combined height of the middle and bottom portions of the first trench;
• a first inter-layer dielectric layer formed between the first trench and the second trench in an interposed manner;
• a second inter-layer dielectric layer patterned over the first inter-layer dielectric layer and including openings that define the widths of the top portions of the first and second trenches, the second inter-layer dielectric layer comprising (i) a top surface having a first width, (ii) a bottom portion disposed below the top surface relative to the substrate and having a second width that is greater than the first width, and (iii) a middle portion disposed between the top surface and the bottom portion of the second inter-layer dielectric layer and having a width that continuously decreases in a direction from the bottom portion to the top surface, wherein the second inter-layer dielectric layer is different from the first inter-layer dielectric layer;
• and
• an oxidation film that coats the second inter-layer dielectric layer, wherein the oxidation film coats the top surface of the second inter-layer dielectric layer and the middle portion of the second inter-layer dielectric layer such that a tapered shape formed by the top surface and the middle portion is maintained,
• wherein the oxidation film, the first spacer material, the first inter-layer dielectric layer, and the second inter-layer dielectric layer converge at the first height of the first spacer material.

A fin field effect transistor (FinFET), comprising:

• a first inter-layer dielectric layer formed on a substrate;
• a second inter-layer dielectric layer formed over the first inter-layer dielectric layer, the second inter-layer dielectric layer including (i) openings formed therein that are aligned with openings of the first inter-layer dielectric layer, and (ii) a structure between adjacent openings that comprises a top surface having a first width, a bottom portion disposed below the top surface relative to the substrate and having a second width that is greater than the first width, and a middle portion disposed between the top surface and the bottom portion of the second inter-layer dielectric layer and having a width that continuously decreases in a direction from the bottom portion to the top surface, wherein the second inter-layer dielectric layer is different from the first inter-layer dielectric layer;
• spacer material adjacent to lateral sides of the first inter-layer dielectric layer in the openings of the first inter-layer dielectric layer, the spacer material comprising tapered portions with thicknesses that continuously decrease as a distance from the substrate increases, wherein the spacer material has a first height on a first side that is equal to a thickness of the first inter-layer dielectric layer and;
• metallic gate material formed inside the openings of the first and second inter-layer dielectric layers;
• and
• an oxidation film that coats the second inter-layer dielectric layer and the spacer material, wherein the oxidation film coats the top surface of the second inter-layer dielectric layer and the middle portion of the second inter-layer dielectric layer such that a tapered shape formed by the top surface and the middle portion is maintained,
• wherein the oxidation film, the spacer material, the first inter-layer dielectric layer, and the second inter-layer dielectric layer converge at the first height of the spacer material.