Tight pitch via structures enabled by orthogonal and non-orthogonal merged vias

A back end of line metallization interconnect structure, comprising:

• a first wire segment in a first metallization layer;
• a second wire segment in a second metallization layer, wherein the end of the second wire segment is above the end of the first wire segment, and the first wire segment is orthogonal to the second wire segment;
• a third wire segment in the first metallization layer;
• a fourth wire segment in the second metallization layer, wherein the end of the fourth wire segment is above the end of the third wire segment, and the third wire segment is orthogonal to the fourth wire segment, and wherein the fourth wire segment is co-linear with the second wire segment;
• a fifth wire segment in the first metallization layer;
• and
• a sixth wire segment in the second metallization layer, wherein the end of the sixth wire segment is above the end of the fifth wire segment, and the fifth wire segment is orthogonal to the sixth wire segment, and the fifth wire segment is orthogonal to the first wire segment and the third wire segment.

A method of forming a merged via, comprising:

• forming a plurality of metal lines in a first metallization layer on a substrate, wherein each adjacent pair of metal lines is separated by a dielectric line;
• forming a cap layer on each dielectric line;
• forming a dielectric layer on the plurality of metal lines in a first metallization layer and cap layers;
• forming a hard mask layer on the dielectric layer;
• forming a plurality of trench templates on the hard mask layer;
• forming a via mask layer on the plurality of trench templates;
• and
• forming a merged via opening in the via mask layer, wherein the via mask opening includes a compound shape having a first rectangular opening portion and a second rectangular opening portion that intersect at an angle.