Previous layer self-aligned via and plug patterning for back end of line (BEOL) interconnects

A method of fabricating an interconnect structure for an integrated circuit, the method comprising:

• providing a previous layer metallization structure comprising an alternating metal line and dielectric line grating pattern having a first direction;
• forming a polymer structure above the grating pattern, the polymer structure comprising a first polymer species disposed above and aligned with the metal lines of the grating pattern and a second polymer species disposed above and aligned with the dielectric lines of the grating pattern;
• removing the first polymer species from the polymer structure;
• forming a sacrificial material above and aligned with the metal lines of the grating pattern, and adjacent to the second polymer species;
• removing the second polymer species from the polymer structure;
• forming a first permanent dielectric layer above and aligned with the dielectric lines of the grating pattern, and adjacent to the sacrificial material;
• replacing the sacrificial material with a second permanent dielectric layer, the second permanent dielectric material layer disposed above and aligned with the metal lines of the grating pattern, and adjacent to the first permanent dielectric layer;
• forming a plurality of trenches in the first permanent dielectric layer and in the second permanent dielectric layer, the plurality of trenches having a grating pattern having a second direction, perpendicular to the first direction;
• forming a dielectric material in the plurality of trenches;
• etching one or more via locations in the second permanent dielectric layer, exposing portions of the metal lines of the grating pattern of the previous layer metallization structure;
• protecting one or more plug locations by forming a hardmask pattern on portions of the first permanent dielectric layer;
• recessing exposed portions of the first and second permanent dielectric layers;
• and
• forming a metal layer in the recessed portions of the first and second permanent dielectric layers.