Methods of forming a low-resistance source/drain feature for a multi-gate device are provided. A example method includes forming a fin-shaped structure that includes a plurality of channel layers interleaved by a plurality of sacrificial layers, recessing a source/drain region of the fin-shaped structure to form a source/drain recess, selectively and partially recessing sidewalls of the plurality of sacrificial layers to form inner spacer recesses, forming inner spacers in the inner spacer recesses, forming a bottom dielectric layer over the substrate, depositing a first epitaxial layer over the inner spacers and the sidewalls of the plurality of the channel layers, performing a thermal treatment to reshape the first epitaxial layer, after the performing of the thermal treatment, depositing a second epitaxial layer over the first epitaxial layer. The first epitaxial layer includes germanium and the second epitaxial layer is free of germanium.

A semiconductor structure and a method of forming the same are provided. In an embodiment, an exemplary method includes forming a fin-shaped active region over a substrate and comprising a number of channel layers interleaved by a number of sacrificial layers, removing a source/drain region of the fin-shaped active region to form a source/drain opening, forming a source/drain feature in the source/drain opening, selectively removing the number of sacrificial layers to form a number of gate openings, and forming a gate structure in the number of gate openings, where the gate structure includes a first portion formed in a first gate opening of the number of gate openings and a second portion formed in a second gate opening of the number of gate openings, a gate length of the first portion is different from a gate length of the second portion.

Inner spacers between a source/drain region of a nanostructure transistor and sacrificial nanostructure layers of the nanostructure transistor are removed prior to formation of a gate structure of the nanostructure transistor. The sacrificial nanostructure layers are removed, and then the inner spacers are removed. The sacrificial nanostructure layers are then replaced with the gate structure of the nanostructure transistor such that the gate structure and the source/drain region are spaced apart by air gaps that result from the removal of the inner spacers. The dielectric constant (or relative permittivity) of the air gaps between the source/drain region and the gate structure is less than the dielectric constant of the material of the inner spacers. The lesser dielectric constant of the air gaps reduces the amount of capacitance between the source/drain region and the gate structure.

A method of forming a complementary field-effect transistor (CFET) device includes: forming a plurality of channel regions stacked vertically over a fin; forming an isolation structure between a first subset of the plurality of channel regions and a second subset of the plurality of channel regions; forming a gate dielectric material around the plurality of channel regions and the isolation structure; forming a work function material around the gate dielectric material; forming a silicon-containing passivation layer around the work function material; after forming the silicon-containing passivation layer, removing a first portion of the silicon-containing passivation layer disposed around the first subset of the plurality of channel regions and keeping a second portion of the silicon-containing passivation layer disposed around the second subset of the plurality of channel regions; and after removing the first portion of the silicon-containing passivation layer, forming a gate fill material around the plurality of channel regions.

A semiconductor device and a manufacturing method thereof are provided. The semiconductor device includes a semiconductor substrate, semiconductor nanosheets vertically stacked upon one another and disposed above the semiconductor substrate, a gate structure surrounding each of the semiconductor nanosheets, inner spacers laterally covering the gate structure and interposed between the semiconductor nanosheets, and source/drain (S/D) regions disposed over the semiconductor substrate and laterally abutting the semiconductor nanosheets. The semiconductor nanosheets serve as channel regions. A bottommost inner spacer of the inner spacers underlying a bottommost semiconductor nanosheet of the semiconductor nanosheets is thinner than a topmost inner spacer of the inner spacers underlying a topmost semiconductor nanosheet of the semiconductor nanosheets. The S/D regions are separated from the gate structure through the inner spacers.

Semiconductor structures and methods for manufacturing the same are provided. The semiconductor structure includes an isolation structure formed over a substrate, and first nanostructures formed over an isolation structure along a first direction. The semiconductor includes second nanostructures adjacent to the first nanostructure along the first direction. The semiconductor also includes a dielectric wall between the first nanostructures and the second nanostructures, and the dielectric wall includes a low-k dielectric material. The dielectric wall is in direct contact with the first nanostructures and the second nanostructures, and a top surface of the dielectric wall is higher than a top surface of the isolation structure. The semiconductor includes a gate structure formed over the first nanostructures along a second direction, and a cutting structure formed over the dielectric wall. The gate structure is divided into two portions by the cutting structure.

A semiconductor device comprising: a substrate including an active pattern; a channel pattern on the active pattern, wherein the channel pattern includes a plurality of semiconductor patterns; a source/drain pattern connected to the plurality of semiconductor patterns; a gate electrode extending in a first direction on the channel pattern, wherein the gate electrode includes an inner gate electrode between first and second semiconductor patterns among the plurality of semiconductor patterns; and an inner gate spacer between the inner gate electrode and the source/drain pattern, wherein the inner gate spacer includes a center portion and an edge portion, the center portion has a first thickness in a second direction, the edge portion has a second thickness in the second direction, the first thickness is greater than the second thickness, the first and second semiconductor patterns are adjacent to each other in a third direction.

A method includes alternately stacking first semiconductor layers and second semiconductor layers over a substrate, patterning the first and second semiconductor layers into a fin structure, forming a dummy gate structure across the fin structure, depositing gate spacers over sidewalls of the dummy gate structure, removing the dummy gate structure to form a recess, removing the first semiconductor layers, depositing an interfacial layer wrapping the second semiconductor layers, depositing a high-k dielectric layer over the interfacial layer and over the sidewalls of the gate spacers, depositing a first gate electrode over the high-k dielectric layer, recessing the first gate electrode and the high-k dielectric layer to expose a top portion of the sidewalls of the gate spacers, depositing a low-k dielectric layer over the recessed high-k dielectric layer, and depositing a second gate electrode over the first gate electrode.

A method for manufacturing a gate-all-around TFET device. The method comprises: forming, on a substrate, a channel stack comprising channel layer(s) and sacrificial layer(s) that alternate with each other; forming, on the substrate, a dummy gate astride the channel stack; forming a first spacer at a surface of the dummy gate; etching the sacrificial layer(s) to form recesses on side surfaces of the channel stack; forming second spacers in the recesses, respectively; fabricating a source and a drain separately, where a region for fabricating the source is shielded by a dielectric material when fabricating the drain, and a region for fabricating the drain is shielded by another dielectric material when fabricating the source; etching the dummy gate and the sacrificial layer(s) to form a space for a surrounding gate; and fabricating a surrounding dielectric-metal gate in the space.

The present disclosure describes a semiconductor device and methods for forming the same. The semiconductor device includes nanostructures on a substrate and a source/drain region in contact with the nanostructures. The source/drain region includes epitaxial end caps, where each epitaxial end cap is formed at an end portion of a nanostructure of the nanostructures. The source/drain region also includes an epitaxial body in contact with the epitaxial end caps and an epitaxial top cap formed on the epitaxial body. The semiconductor device further includes gate structure formed on the nanostructures.