Semiconductor structure including low-resistance interconnect and integrated circuit device having the same

A semiconductor structure, comprising:

• a first metal feature in a first dielectric layer;
• a first conductive feature and a second conductive feature extending over the first dielectric layer, wherein the first conductive feature is directly over and electrically coupled to the first metal feature via a metal cap and the metal cap is disposed in the first dielectric layer;
• and
• an isolation feature over the first dielectric layer and disposed between the first conductive feature and the second conductive feature,
• wherein the isolation feature includes an encapsulating layer and a dielectric filling layer over the encapsulating layer, wherein the encapsulating layer comprises a first portion on the first dielectric layer and a second portion extending on sidewalls of the first conductive feature and the second conductive feature.

An integrated circuit device comprising:

• a first metal feature in a dielectric layer and a capping layer over the first metal feature;
• and
• a second metal feature coupled to the capping layer at an interface, wherein sidewalls of the second metal feature are lined by an encapsulating layer, and the encapsulating layer comprises silicon oxide, silicon oxycarbide, silicon oxynitride, silicon carbonitride, or silicon oxy-carbonitride,
• wherein the capping layer and the interface are free of metal nitride.