A semiconductor device according to the present disclosure includes a first source/drain epitaxial feature and a second source/drain epitaxial feature each having an outer liner layer and an inner filler layer, a plurality of channel members extending between the first source/drain epitaxial feature and the second source/drain epitaxial feature along a first direction, and a gate structure disposed over and around the plurality of channel members. The plurality of channel members are in contact with the outer liner layer and are spaced apart from the inner filler layer. The outer liner layer comprises germanium and boron and the inner filler layer comprises germanium and gallium.

Integrated circuit structures having backside gate cut or backside trench contact cut, and methods of fabricating integrated circuit structures having backside gate cut or backside trench contact cut, are described. For example, an integrated circuit structure includes a first sub-fin structure over a first stack of nanowires. A second sub-fin structure is over a second stack of nanowires. A first gate electrode is around the first stack of nanowires. A second gate electrode is around the second stack of nanowires. A dielectric structure is between the first gate electrode and the second gate electrode. The dielectric structure is continuous along an entirety of a height of the first gate electrode and the first sub-fin structure.

Embodiments of the disclosure are in the field of advanced integrated circuit structure fabrication and, in particular, integrated circuit structures having channel structures with sub-fin dopant diffusion blocking layers are described. In an example, an integrated circuit structure includes a fin having a lower fin portion and an upper fin portion. The lower fin portion includes a dopant diffusion blocking layer on a first semiconductor layer doped to a first conductivity type. The upper fin portion includes a portion of a second semiconductor layer, the second semiconductor layer on the dopant diffusion blocking layer. An isolation structure is along sidewalls of the lower fin portion. A gate stack is over a top of and along sidewalls of the upper fin portion, the gate stack having a first side opposite a second side. A first source or drain structure at the first side of the gate stack.

Gate-all-around integrated circuit structures having source or drain structures with epitaxial nubs, and methods of fabricating gate-all-around integrated circuit structures having source or drain structures with epitaxial nubs, are described. For example, an integrated circuit structure includes a first vertical arrangement of horizontal nanowires and a second vertical arrangement of horizontal nanowires. A first pair of epitaxial source or drain structures includes vertically discrete portions aligned with the first vertical arrangement of horizontal nanowires. A second pair of epitaxial source or drain structures includes vertically discrete portions aligned with the second vertical arrangement of horizontal nanowires. A conductive contact structure is laterally between and in contact with the one of the first pair of epitaxial source or drain structures and the one of the second pair of epitaxial source or drain structures.

A method of forming a semiconductor device includes forming a first fin and a second fin protruding above a substrate; forming isolation regions on opposing sides of the first fin and the second fin; forming a metal gate over the first fin and over the second fin, the metal gate being surrounded by a first dielectric layer; and forming a recess in the metal gate between the first fin and the second fin, where the recess extends from an upper surface of the metal gate distal the substrate into the metal gate, where the recess has an upper portion distal the substrate and a lower portion between the upper portion and the substrate, where the upper portion has a first width, and the lower portion has a second width larger than the first width, the first width and the second width measured along a longitudinal direction of the metal gate.

A device includes a fin protruding from a semiconductor substrate; a gate stack over and along a sidewall of the fin; a gate spacer along a sidewall of the gate stack and along the sidewall of the fin; an epitaxial source/drain region in the fin and adjacent the gate spacer; and a corner spacer between the gate stack and the gate spacer, wherein the corner spacer extends along the sidewall of the fin, wherein a first region between the gate stack and the sidewall of the fin is free of the corner spacer, wherein a second region between the gate stack and the gate spacer is free of the corner spacer.

A device includes a semiconductor substrate, a first fin arranged over the semiconductor substrate, and an isolation structure. The first fin includes an upper portion, a bottom portion, and an insulator layer between the upper portion and the bottom portion. A top surface of the insulator layer is wider than a bottom surface of the upper portion of the first fin. The isolation structure surrounds the bottom portion of the first fin.

A semiconductor structure includes semiconductor layers disposed over a substrate and oriented lengthwise in a first direction, a metal gate stack disposed over the semiconductor layers and oriented lengthwise in a second direction perpendicular to the first direction, where the metal gate stack includes a top portion and a bottom portion that is interleaved with the semiconductor layers, source/drain features disposed in the semiconductor layers and adjacent to the metal gate stack, and an isolation structure protruding from the substrate, where the isolation structure is oriented lengthwise along the second direction and spaced from the metal gate stack along the first direction, and where the isolation structure includes a dielectric layer and an air gap.

A nitrogen plasma treatment is used on an adhesion layer of a contact plug. As a result of the nitrogen plasma treatment, nitrogen is incorporated into the adhesion layer. When a contact plug is deposited in the opening, an interlayer of a metal nitride is formed between the contact plug and the adhesion layer. A nitrogen plasma treatment is used on an opening in an insulating layer. As a result of the nitrogen plasma treatment, nitrogen is incorporated into the insulating layer at the opening. When a contact plug is deposited in the opening, an interlayer of a metal nitride is formed between the contact plug and the insulating layer.

A semiconductor device includes an active fin on a substrate, a gate electrode and intersecting the active fin, gate spacer layers on both side walls of the gate electrode, and a source/drain region in a recess region of the active fin at at least one side of the gate electrode. The source/drain region may include a base layer in contact with the active fin, and having an inner end and an outer end opposing each other in the first direction on an inner sidewall of the recess region. The source/drain region may include a first layer on the base layer. The first layer may include germanium (Ge) having a concentration higher than a concentration of germanium (Ge) included in the base layer. The outer end of the base layer may contact the first layer, and may have a shape convex toward outside of the gate electrode on a plane.