Self-enclosed asymmetric interconnect structures

A multilayer integrated circuit device, comprising:

• a first insulator structure having a metal feature therein;
• a second insulator structure having a metal feature therein;
• an electromigration barrier layer between the first and second insulator structures, the electromigration barrier layer having a relatively lower etch rate for a given etchant than the second insulator structure, the electromigration barrier layer including a convex protrusion, wherein the first insulator structure, the electromigration barrier layer, and the second insulator structure are arranged in a vertical stack, wherein the electromigration barrier layer is a single layer having no discernible interface within that electromigration barrier layer;
• and
• a conductive interconnect feature connecting the metal feature of the first insulator structure to the metal feature of the second insulator structure, the conductive interconnect feature passing through both the electromigration barrier layer and the second insulator structure in at least one horizontal common plane, wherein the conductive interconnect feature includes an asymmetric taper that causes a concave depression on only one side of the the conductive interconnect feature, wherein the concave depression tapers towards an opposing side of the conductive interconnect feature to cause the conductive interconnect feature to only partially land on the metal feature of the first insulator structure, and wherein the concave depression of the conductive interconnect feature is conformal to the convex protrusion of the electromigration barrier layer.

A method for forming a semiconductor device, comprising:

• providing a first insulator structure having a metal feature therein;
• providing a second insulator structure having a metal feature therein, wherein the second insulator structure is a single layer having no discernible interface within the single layer;
• providing an intervening layer that is distinct from and between the first and second insulator structures, the intervening layer having a relatively lower etch rate for a given etchant than the second insulator structure, the intervening layer including a convex protrusion, wherein the first insulator structure, the intervening layer, and the second insulator structure are arranged in a vertical stack;
• and
• providing a conductive interconnect feature connecting the metal feature of the first insulator structure to the metal feature of the second insulator structure, the conductive interconnect feature passing through both the intervening layer and the second insulator structure in at least one horizontal common plane, wherein the conductive interconnect feature includes an asymmetric taper that causes a concave depression on only one side of the conductive interconnect feature, wherein the concave depression tapers towards an opposing side of the conductive interconnect feature to cause the conductive interconnect feature to at least partially land on the metal feature of the first insulator structure, and wherein the concave depression of the conductive interconnect feature is conformal to the convex protrusion of the intervening layer.