A semiconductor device and a method of forming the same are provided. In an embodiment, an exemplary semiconductor device includes two stacks of channel members; a source/drain feature extending between the two stacks of channel members along a direction; a source/drain contact disposed under and electrically coupled to the source/drain feature; two gate structures over and interleaved with the two stacks of channel members; a low-k spacer horizontally surrounding the source/drain contact; and a dielectric layer horizontally surrounding the low-k spacer.

A method of forming a semiconductor structure is provided. The method includes forming a gate structure over an active region of a substrate, forming an epitaxial layer comprising first dopants of a first conductivity type over portions of the active region on opposite sides of the gate structure, the epitaxial layer, applying a cleaning solution comprising ozone and deionized water to the epitaxial layer, thereby forming an oxide layer on the epitaxial layer, forming a patterned photoresist layer over the oxide layer and the gate structure to expose a portion of the oxide layer, forming a contact region second dopants of a second conductivity type opposite the first conductivity type in the portion of the epitaxial layer not covered by the patterned photoresist layer, and forming a contact overlying the contact region.

A semiconductor device includes a source/drain region, a source/drain silicide layer formed on the source/drain region, and a first contact disposed over the source/drain silicide layer. The first contact includes a first metal layer, an upper surface of the first metal layer is at least covered by a silicide layer, and the silicide layer includes a same metal element as the first metal layer.

Techniques and mechanisms for operating transistors that are in a stacked configuration. In an embodiment, an integrated circuit (IC) device includes transistors arranged along a line of direction which is orthogonal to a surface of a semiconductor substrate. A first epitaxial structure and a second epitaxial structure are coupled, respectively, to a first channel structure of a first transistor and a second channel structure of a second transistor. The first epitaxial structure and the second epitaxial structure are at different respective levels relative to the surface of the semiconductor substrate. A dielectric material is disposed between the first epitaxial structure and the second epitaxial structure to facilitate electrical insulation of the channels from each other. In another embodiment, the stacked transistors are coupled to provide a complementary metal-oxide-semiconductor (CMOS) inverter circuit.

A semiconductor device and its fabrication method are provided in the present disclosure. The method includes providing a substrate; forming a plurality of fins spaced apart on the substrate; forming a dummy gate structure across the plurality of fins and on the substrate; forming a first sidewall spacer on a sidewall of the dummy gate structure; forming an interlayer dielectric layer on the substrate and the fins, and on a portion of a sidewall of the first sidewall spacer, where a top of the interlayer dielectric layer is lower than a top of the first sidewall spacer; and forming a second sidewall spacer on the interlayer dielectric layer and on a sidewall of the first sidewall spacer.

An integrated circuit includes a first nanostructure transistor including a plurality of first semiconductor nanostructures over a substrate and a source/drain region in contact with each of the first semiconductor nanostructures. The integrated circuit includes a second nanostructure transistor including a plurality of second semiconductor nanostructures and a second source/drain region in contact with one or more of the second semiconductor nanostructures but not in contact with one or more other second semiconductor nanostructures.

A method of fabricating a semiconductor device includes forming at least one fin on a substrate, a plurality of dummy gates over the at least one fin, and a sidewall spacer on the dummy gates. Source and drain regions are epitaxially formed contacting the at least one fin and laterally adjacent the dummy gates, where forming the source and drain regions leaves a void below the source and drain regions and adjacent the dummy gates. The dummy gates are replaced with active gates, each having a gate dielectric on the sidewall spacer and a gate electrode on the gate dielectric. A patterned layer is formed exposing a selected active gate of the active gates. A first etch is performed to remove exposed portions of the gate electrode of the selected active gate. A second etch is performed, after the first etch, to remove exposed portions of a gate dielectric of the selected active gate.

A technique relates to a semiconductor device. A source/drain layer is formed. Fins with gate stacks are formed in a fill material, a dummy fin template including at least one fin of the fins and at least one gate stack of the gate stacks, the fins being formed on the source/drain layer. A trench is formed through the fill material by removing the dummy fin template, such that a portion of the source/drain layer is exposed in the trench. A source/drain metal contact is formed on the portion of the source/drain layer in the trench.

Techniques herein include methods of forming channel structures for field effect transistors having a channel current path parallel to a surface of a substrate. 3D in-situ horizontal or lateral growth of the channel and source/drain regions allows for a custom doping in the 3D horizontal nanosheet direction for NMOS and PMOS devices. An ultra-short channel length is achieved with techniques herein because the channel is epitaxially grown in the 3D horizontal nanosheet direction at the monolayer level. Since the channel is grown in a dielectric cavity, a precise channel cross sectional area can be tuned.

A method of forming a semiconductor device structure is provided. The method includes forming semiconductor fins at a first conductivity type region and a second conductivity type region of a substrate, forming a sacrificial gate structure across a portion of the semiconductor fins, wherein the sacrificial gate structure comprises a sacrificial gate dielectric layer and a sacrificial gate electrode layer over the sacrificial gate dielectric layer, and the sacrificial gate dielectric layer on the semiconductor fins of the first conductivity type region is asymmetrical in thickness between a top and a sidewall of the semiconductor fins. The method also includes forming a gate spacer on opposite sidewalls of the sacrificial gate structure, recessing the semiconductor fins not covered by the sacrificial gate structure and the gate spacer, forming source/drain feature on the recessed semiconductor fins, and removing the sacrificial gate structure to expose the top of the semiconductor fins.