US Patent 11908731 Via-first self-aligned interconnect formation process

A structure includes a dielectric layer, and a metal line in the dielectric layer. The metal line has a first straight edge and a second straight edge extending in a lengthwise direction of the metal line. The first straight edge and the second straight edge are parallel to each other. A via is underlying and joined to the metal line. The via has a third straight edge underlying and vertically aligned to the first straight edge, and a first curved edge and a second curved edge connecting to opposite ends of the third straight edge.