A second metal structure such as a metal plug is formed over a first metal structure, such as a metal line, by causing metal material from the first metal structure to migrate into an opening in a dielectric layer over the first metal structure. The metal material, which may be copper, is of a type that undergoes a reduction in density as it oxidizes. Migration is induced using gases that alternately oxidize and reduce the metal material. Over many cycles, the metal material migrates into the opening. In some embodiments, the migrated metal material partially fills the opening. In some embodiments, the migrated metal material completely fills the opening.

A method includes forming a conductive pad over an interconnect structure of a wafer, forming a capping layer over the conductive pad, forming a dielectric layer covering the capping layer, and etching the dielectric layer to form an opening in the dielectric layer. The capping layer is exposed to the opening. A wet-cleaning process is then performed on the wafer. During the wet-cleaning process, a top surface of the capping layer is exposed to a chemical solution used for performing the wet-cleaning process. The method further includes depositing a conductive diffusion barrier extending into the opening, and depositing a conductive material over the conductive diffusion barrier.

Methods of processing thin film by oxidation at high pressure are described. The methods are generally performed at pressures greater than 2 bar. The methods can be performed at lower temperatures and have shorter exposure times than similar methods performed at lower pressures. Some methods relate to oxidizing tungsten films to form self-aligned pillars.

The present disclosure describes a method for forming a barrier structure between liner-free conductive structures and underlying conductive structures. The method includes forming openings in a dielectric layer disposed on a contact layer, where the openings expose conductive structures in the contact layer. A first metal layer is deposited in the openings and is grown thicker on top surfaces of the conductive structures and thinner on sidewall surfaces of the openings. The method further includes exposing the first metal layer to ammonia to form a bilayer with the first metal layer and a nitride of the first metal layer, and subsequently exposing the nitride to an oxygen plasma to convert a portion of the nitride of the first metal layer to an oxide layer. The method also includes removing the oxide layer and forming a semiconductor-containing layer on the nitride of the first metal layer.

Semiconductor structures and method for forming the same are provided. The semiconductor structure includes a substrate and a gate structure formed over the substrate. The semiconductor structure further includes a source/drain structure formed adjacent to the gate structure in the substrate and a contact formed over the source/drain structure. The semiconductor structure further includes a metal-containing layer formed over the contact and a dielectric layer covering the gate structure and the metal-containing layer. The semiconductor structure further includes a first conductive structure formed through dielectric layer and the metal-containing layer and landing on the contact. In addition, a bottom surface of the metal-containing layer is higher than a top surface of the gate structure.

The present disclosure describes a method for forming a barrier structure between liner-free conductive structures and underlying conductive structures. The method includes forming openings in a dielectric layer disposed on a contact layer, where the openings expose conductive structures in the contact layer. A first metal layer is deposited in the openings and is grown thicker on top surfaces of the conductive structures and thinner on sidewall surfaces of the openings. The method further includes exposing the first metal layer to ammonia to form a bilayer with the first metal layer and a nitride of the first metal layer, and subsequently exposing the nitride to an oxygen plasma to convert a portion of the nitride of the first metal layer to an oxide layer. The method also includes removing the oxide layer and forming a semiconductor-containing layer on the nitride of the first metal layer.

A method is provided. The method includes forming an interconnect structure electrically connected to a semiconductor device; forming a tantalum-based barrier layer over the interconnect structure; oxidizing the tantalum-based barrier layer to form a tantalum oxide over the tantalum-based barrier layer; and forming a metal layer over the tantalum oxide.

An interconnect structure is provided. The interconnect structure includes a first via in a first dielectric layer, a first metal line on and electrically connected to the first via, a first etching stop layer over the first dielectric layer, a second metal line over the first etching stop layer, and an encapsulating layer. The encapsulating layer includes a first vertical portion along a sidewall of the first metal line, a horizontal portion along an upper surface of the first etching stop layer, and a second vertical portion along a sidewall of the second metal line. The interconnect structure also includes a second dielectric layer nested within the encapsulating layer.

A method for filling recessed features with a low-resistivity metal includes providing a patterned substrate containing a recessed feature formed in a first layer and a second layer that is exposed in the recessed feature, pre-treating the substrate with a surface modifier that increases metal deposition selectivity on the second layer relative to on the first layer, and depositing a metal layer on the substrate by vapor phase deposition, where the metal layer is preferentially deposited on the second layer in the recessed feature. The method further includes removing metal nuclei deposited on the first layer, including on a field area and on sidewalls of the first layer in the recessed feature, to selectively form the metal layer on the second layer in the recessed feature, where the removing includes exposing the patterned substrate to an etching gas containing ozone.

A method includes depositing a dielectric cap over a gate structure. A source/drain contact is formed over a source/drain region after forming the dielectric cap. A top of the dielectric cap is doped to form a doped region in the dielectric cap. After doping the top of the dielectric cap, a etch stop layer and an interlayer dielectric (ILD) layer are deposited over the dielectric cap. A via opening is formed to extend though the ILD layer and the etch stop layer to expose the source/drain contact. A source/drain via is filled in the via opening.