Interconnect structures with fully aligned vias

A structure comprising:

• a trench stop hardmask above and in direct contact with a first ILD;
• a cap layer covering the a portion of a first metal line in the first ILD, wherein the cap layer is in direct contact with a top surface of the first metal line and sidewalls of the first ILD, and wherein an uppermost surface of a portion of the cap layer is substantially flush with an uppermost surface of the trench stop hardmask such that the cap layer is entirely below the uppermost surface of the trench stop hardmask;
• a second ILD on the cap layer;
• and
• a via extending vertically from the top surface of the first metal line to a bottom surface of a second metal line, wherein the second metal line is above and perpendicular to the first metal line, the via is fully aligned to the first metal line and the second metal line.