A semiconductor structure and a method of forming the same are provided. In an embodiment, a semiconductor structure includes a first plurality of channel members over a backside dielectric layer, a second plurality of channel members over the backside dielectric layer, a silicide feature disposed in the backside dielectric layer, and a source/drain feature disposed over the silicide feature and extending between the first plurality of channel members and the second plurality of channel members. The silicide feature extends through an entire depth of the backside dielectric layer.

An integrated circuit device includes a substrate including first and second fin-type active areas, a gate structure on the first and second fin-type active areas, first and second source/drain regions on the first and second fin-type active areas, respectively, a first source/drain contact on the first source/drain region and comprising first and second portions, a second source/drain contact on the second source/drain region and comprising first and second portions, the second portion having an upper surface at a lower level than an upper surface of the first portion, a first stressor layer on the upper surface of the second portion of the first source/drain contact, and a second stressor layer on the upper surface of the second portion of the second source/drain contact, the second stressor layer including a material different from a material included in the first stressor layer.

Integrated circuitry comprising transistor structures having a channel portion over a base portion of fin. The base portion of the fin is an insulative amorphous oxide, or a counter-doped crystalline material. Transistor structures, such as channel portions of a fin and source and drain materials may be first formed with epitaxial processes seeded by a front side of a crystalline substrate. Following front side processing, a backside of the transistor structures may be exposed and the base portion of the fin modified from the crystalline substrate composition into the amorphous oxide or counter-doped crystalline material using backside processes and low temperatures that avoid degradation to the channel material while reducing transistor off-state leakage.

Contact over active gate (COAG) structures with conductive trench contact taps are described. In an example, an integrated circuit structure includes a plurality of gate structures above a substrate, each of the gate structures including a gate insulating layer thereon. A plurality of conductive trench contact structures is alternating with the plurality of gate structures, each of the conductive trench contact structures including a trench insulating layer thereon. One of the plurality of conductive trench contact structures includes a conductive tap structure protruding through the corresponding trench insulating layer. An interlayer dielectric material is above the trench insulating layers and the gate insulating layers. A conductive structure is in direct contact with the conductive tap structure of the one of the plurality of conductive trench contact structures.

A long channel field-effect transistor is incorporated in a semiconductor structure. A semiconductor fin forming a channel region is configured as a loop having an opening therein. A dielectric isolation region is within the opening. Source/drain regions epitaxially grown on fin end portions within the opening are electrically isolated by the isolation region. The source/drain regions, the isolation region and the channel are arranged as a closed loop. The semiconductor structure may further include a short channel, vertical transport field-effect transistor.

Gate aligned contacts and methods of forming gate aligned contacts are described. For example, a method of fabricating a semiconductor structure includes forming a plurality of gate structures above an active region formed above a substrate. The gate structures each include a gate dielectric layer, a gate electrode, and sidewall spacers. A plurality of contact plugs is formed, each contact plug formed directly between the sidewall spacers of two adjacent gate structures of the plurality of gate structures. A plurality of contacts is formed, each contact formed directly between the sidewall spacers of two adjacent gate structures of the plurality of gate structures. The plurality of contacts and the plurality of gate structures are formed subsequent to forming the plurality of contact plugs.

A semiconductor device includes an active region extending on a substrate in a first direction, a gate electrode intersecting the active region and extending in a second direction, perpendicular to the first direction, a contact structure disposed on the active region on one side of the gate electrode and extending in the second direction, and a first via disposed on the contact structure to be connected to the contact structure and has a shape in which a length in the second direction is greater than a length in the first direction. A plurality of first metal interconnections are provided, which extend in the first direction on the first via, and are connected to the first via. A second via is provided, which is disposed on the plurality of first metal interconnections to be connected to the plurality of first metal interconnections and has a shape in which a length in the second direction is greater than a length in the first direction.

A semiconductor structure and its fabrication method are provided. The semiconductor structure includes: a substrate including a base substrate, fins, and an isolation structure; a first dielectric layer; gate structures in the first dielectric layer, where each gate structure includes a gate electrode layer and a gate dielectric layer; air spacers and second spacers on sidewalls of gate electrode layers, where the air spacers are located between the gate electrode layers and the second spacers to expose the sidewalls of the gate electrode layers and the second spacers; source/drain layers in the fins at sides of each gate structure; first conductive structures in the first dielectric layer and on the source/drain layers; and a second dielectric layer on the first dielectric layer and the gate structures, located on the air spacers. The air spacers are also located between the first conductive structures and the gate electrode layers.

Embodiments of the invention are directed to a transistor device that includes a channel stack having stacked, spaced-apart, channel layers. A first source or drain (S/D) region is communicatively coupled to the channel stack. A tunnel extends through the channel stack, wherein the tunnel includes a central region and a first set of end regions. The first set of end regions is positioned closer to the first S/D region than the central region is to the first S/D region. A first type of work-function metal (WFM) is formed in the first set of end regions, the first WFM having a first work-function (WF). A second type of WFM is formed in the central region, the second type of WFM having a second WF, wherein the first WF is different than the second WF.

Semiconductor structure and forming method thereof are provided. The forming method includes: forming a substrate including a power rail region, the power rail region including a first area and a second area, the power rail region having a first fin and a second fin spanning the second area; forming sidewall spacers on sidewall surfaces of the first fin and the second fin after forming the first fin and the second fin; forming a first patterned layer on the substrate, the first patterned layer having a first opening in the first patterned layer exposing the power rail region; etching the substrate using the first patterned layer as a mask to form power rail openings in the substrate; forming isolation films on inner wall surfaces of the power rail openings; and forming buried power rails in the power rail openings after forming the isolation films.