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 semiconductor device and a method of forming the same are provided. A semiconductor device according to the present disclosure includes a first source/drain feature, a second source/drain feature, a first semiconductor channel member and a second semiconductor channel member extending between the first and second source/drain features, and a first dielectric feature and a second dielectric feature each including a first dielectric layer and a second dielectric layer different from the first dielectric layer. The first and second dielectric features are sandwiched between the first and second semiconductor channel members.

A method includes providing a substrate, an isolation structure, a semiconductor fin having a stack of first and second semiconductor layers, a dummy gate, and outer spacers on opposing sidewalls of the dummy gate; etching the semiconductor fin to form source/drain (S/D) trenches; etching the second semiconductor layers from the S/D trenches to form gaps vertically between the first semiconductor layers; forming inner spacers in the gaps; epitaxially growing S/D features in the S/D trenches; forming an inter-layer dielectric layer over the S/D features; etching the dummy gate and the outer spacers to form a gate-end trench away from the semiconductor fin and over the isolation structure; and forming a gate-end dielectric feature filling the gate-end trench, wherein a dielectric constant of the gate-end dielectric feature is higher than both a dielectric constant of the outer spacers and a dielectric constant of the inner spacers.

The present disclosure is directed to gate-all-around (GAA) transistor structures with a low level of leakage current and low power consumption. For example, the GAA transistor includes a semiconductor layer with a first source/drain (S/D) epitaxial structure and a second S/D epitaxial structure disposed thereon, where the first and second S/D epitaxial structures are spaced apart by semiconductor nano-sheet layers. The semiconductor structure further includes isolation structures interposed between the semiconductor layer and each of the first and second S/D epitaxial structures. The GAA transistor further includes a gate stack surrounding the semiconductor nano-sheet layers.

Sub-fin isolation schemes for gate-all-around (GAA) transistor devices are provided herein. In some cases, the sub-fin isolation schemes include forming one or more dielectric layers between each of the source/drain regions and the substrate. In some such cases, the one or more dielectric layers include material native to the gate sidewall spacers, for example, or other dielectric material. In other cases, the sub-fin isolation schemes include substrate modification that results in oppositely-type doped semiconductor material under each of the source/drain regions and in the sub-fin. The oppositely-type doped semiconductor material results in the interface between that material and each of the source/drain regions being a p-n or n-p junction to block the flow of carriers through the sub-fin. The various sub-fin isolation schemes described herein enable better short channel characteristics for GAA transistors (e.g., employing one or more nanowires, nanoribbons, or nanosheets), thereby improving device performance.

A semiconductor device includes a heat dissipation substrate and a device layer. The thermal conductivity of the heat dissipation substrate is greater than 200 Wm.sup.−1K.sup.−1 and the device layer is disposed on the heat dissipation substrate. The device layer includes a transistor. A method of forming a semiconductor device includes providing a base substrate, forming a heat dissipation substrate on the base substrate, wherein a thermal conductivity of the heat dissipation substrate is greater than 200 Wm.sup.−1K.sup.−1. The method further includes forming a device layer on the heat dissipation substrate, wherein the device layer comprises a transistor. The method further includes removing the base substrate.

The present disclosure describes a semiconductor device includes a first fin structure, an isolation structure in contact with a top surface of the first fin structure, a substrate layer in contact with the isolation structure, an epitaxial layer in contact with the isolation structure and the substrate layer, and a second fin structure above the first fin structure and in contact with the epitaxial layer.

A semiconductor device according to the present disclosure includes a substrate including a plurality of atomic steps that propagate along a first direction, and a transistor disposed on the substrate. The transistor includes a channel member extending a second direction perpendicular to the first direction, and a gate structure wrapping around the channel member.

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.

A semiconductor device includes a substrate including an active region that extends in a first direction; a gate structure that intersects the active region and that extends in a second direction; a source/drain region on the active region on at least one side of the gate structure; a contact plug on the source/drain region on the at least one side of the gate structure; and a contact insulating layer on sidewalls of the contact plug, wherein a lower end of the contact plug is closer to the substrate than a lower end of the source/drain region.