Semiconductor structures and methods of forming the same are provided. In one embodiment, a semiconductor structure includes an active region over a substrate, a gate structure disposed over the active region, and a gate contact that includes a lower portion disposed over the gate structure and an upper portion disposed over the lower portion.

A method of forming a semiconductor structure includes forming a semiconductor device over a substrate, forming a combination of a connection-level dielectric layer and a connection-level metal interconnect structure over the semiconductor device, where the connection-level metal interconnect structure is electrically connected to a node of the semiconductor device and is embedded in the connection-level dielectric layer, forming a line-and-via-level dielectric layer over the connection-level dielectric layer, forming an integrated line-and-via cavity through the line-and-via-level dielectric layer over the connection-level metal interconnect structure, selectively growing a conductive via structure containing cobalt from a bottom of the via portion of the integrated line-and-via cavity without completely filling a line portion of the integrated line-and-via cavity, and forming a copper-based conductive line structure that contains copper at an atomic percentage that is greater than 90% in the line portion of the integrated line-and-via cavity on the conductive via structure.

There is provided a semiconductor device capable of capable of improving element performance and reliability. A semiconductor device includes a lower conductive pattern disposed on a substrate, an upper conductive pattern disposed on the lower conductive pattern, and a first plug pattern disposed between the lower conductive pattern and the upper conductive pattern and connected to the lower conductive pattern and the upper conductive pattern. The first plug pattern includes a first barrier pattern that defines a first plug recess and a first plug metal pattern that fills the first plug recess, and the first plug metal pattern includes a first molybdenum pattern and a first tungsten pattern disposed on the first molybdenum pattern.

A semiconductor device structure, along with methods of forming such, are described. The semiconductor device structure includes a device, a first dielectric material disposed over the device, and an opening is formed in the first dielectric material. The semiconductor device structure further includes a conductive structure disposed in the opening, and the conductive structure includes a first sidewall. The semiconductor device structure further includes a surrounding structure disposed in the opening, and the surrounding structure surrounds the first sidewall of the conductive structure. The surrounding structure includes a first spacer layer and a second spacer layer adjacent the first spacer layer. The first spacer layer is separated from the second spacer layer by an air gap.

Embodiments provide a method and resulting structure that includes forming an opening in a dielectric layer to expose a metal feature, selectively depositing a metal cap on the metal feature, depositing a barrier layer over the metal cap, and depositing a conductive fill on the barrier layer.