A semiconductor device includes a first semiconductor fin, a first epitaxial layer, a first alloy layer and a contact plug. The first semiconductor fin is on a substrate. The first epitaxial layer is on the first semiconductor fin. The first alloy layer is on the first epitaxial layer. The first alloy layer is made of one or more Group IV elements and one or more metal elements, and the first alloy layer comprises a first sidewall and a second sidewall extending downwardly from a bottom of the first sidewall along a direction non-parallel to the first sidewall. The contact plug is in contact with the first and second sidewalls of the first alloy layer.

A semiconductor device structure, along with methods of forming such, are described. The structure includes a substrate, a source/drain contact disposed over the substrate, a first dielectric layer disposed on the source drain contact, an etch stop layer disposed on the first dielectric layer, and a source/drain conductive layer disposed in the etch stop layer and the first dielectric layer. The structure further includes a spacer structure disposed in the etch stop layer and the first dielectric layer. The spacer structure surrounds a sidewall of the source/drain conductive layer and includes a first spacer layer having a first portion and a second spacer layer adjacent the first portion of the first spacer layer. The first portion of the first spacer layer and the second spacer layer are separated by an air gap. The structure further includes a seal layer.

Improved gate structures, methods for forming the same, and semiconductor devices including the same are disclosed. In an embodiment, a semiconductor device includes a gate structure over a semiconductor substrate, the gate structure including a high-k dielectric layer; a gate electrode over the high-k dielectric layer; a conductive cap over and in contact with the high-k dielectric layer and the gate electrode, a top surface of the conductive cap being convex; and first gate spacers on opposite sides of the gate structure, the high-k dielectric layer and the conductive cap extending between opposite sidewalls of the first gate spacers.

A method of manufacturing a semiconductor device includes forming a fin structure including a stacked layer of first semiconductor layers and second semiconductor layers disposed over a bottom fin structure and a hard mask layer over the stacked layer, forming an isolation insulating layer so that the hard mask layer and the stacked layer are exposed from the isolation insulating layer, forming a sacrificial cladding layer over at least sidewalls of the exposed hard mask layer and stacked layer, forming layers of a first dielectric layer and an insertion layer over the sacrificial cladding layer and the fin structure, performing an annealing operation to convert a portion of the layers of the first dielectric layer and the insertion layer from an amorphous form to a crystalline form, and removing the remaining amorphous portion of the layers of the first dielectric layer and the insertion layer to form a recess.

A field effect transistor (FET) structure upon a substrate formed by forming a stack of nanosheets upon a semiconductor substrate, the stack including alternating layers of a compound semiconductor material and an elemental semiconductor material, forming a dummy gate structure upon the stack of nanosheets, recessing the stack of nanosheets in alignment with the dummy gate structure, recessing the compound semiconductor layers beyond the edges of the dummy gate, yielding indentations between adjacent semiconductor nanosheets. Further by filling the indentations with a bi-layer dielectric material, epitaxially growing source/drain regions adjacent to the nanosheet stack and bi-layer dielectric material, removing remaining portions of the compound semiconductor nanosheet layers, recessing the bi-layer dielectric material to expose an inner material layer, and forming gate structure layers in contact with first and second dielectric materials of the bi-layer dielectric material.

Techniques for recovering the width of a top gate spacer in a field-effect transistor (FET) device are provided. In one aspect, a FET device includes: at least one gate; source/drain regions present on opposite sides of the at least one gate; gate spacers offsetting the at least one gate from the source/drain regions, wherein each of the gate spacers includes an L-shaped spacer alongside the at least one gate and a dielectric liner disposed on the L-shaped spacer; and at least one channel interconnecting the source/drain regions. A method of forming a FET device is also provided which includes recovering the width of the top gate spacer using the dielectric liner.

A CFET includes a fin that has a bottom channel portion, a top channel portion, and a channel isolator between the bottom channel portion and the top channel portion. The CFET further includes a source and drain stack that has a bottom source or drain (S/D) region connected to the bottom channel portion, a top S/D region connected to the top channel portion, a source-drain isolator between the bottom S/D region and the top S/D region. The CFET further includes a spacer foot physically connected to a base sidewall portion of the bottom S/D region and a buried S/D contact that is physically connected to an upper sidewall portion of the bottom S/D region. The CFET may further include a common gate around the bottom channel portion, around the top channel portion, and around the channel isolator.

A semiconductor device with air spacers and air caps and a method of fabricating the same are disclosed. The semiconductor device includes a substrate and a fin structure disposed on the substrate. The fin structure includes a first fin portion and a second fin portion. The semiconductor device further includes a source/drain (S/D) region disposed on the first fin portion, a contact structure disposed on the S/D region, a gate structure disposed on the second fin portion, an air spacer disposed between a sidewall of the gate structure and the contact structure, a cap seal disposed on the gate structure, and an air cap disposed between a top surface of the gate structure and the cap seal.

A method of forming a semiconductor device includes: forming a dummy gate over a fin, where the fin protrudes above a substrate; surrounding the dummy gate with a dielectric material; and replacing the dummy gate with a replacement gate structure, where replacing the dummy gate includes: forming a gate trench in the dielectric material, where forming the gate trench includes removing the dummy gate; forming a metal-gate stack in the gate trench, where forming the metal-gate stack includes forming a gate dielectric layer, a first work function layer, and a gap-filling material sequentially in the gate trench; and enlarging a volume of the gap-filling material in the gate trench.

Isolation schemes for gate-all-around (GAA) transistor devices are provided herein Integrated circuit structures including increased transistor source/drain contact area using a sacrificial source/drain layer are provided herein. In some cases, the isolation schemes include changing the semiconductor nanowires/nanoribbons in a targeted channel region between active or functional transistor devices to electrically isolate those active devices. The targeted channel region is referred to herein as a dummy channel region, as it is not used as an actual channel region for an active or functional transistor device. The semiconductor nanowires/nanoribbons in the dummy channel region can be changed by converting them to an electrical insulator and/or by adding dopant that is opposite in type relative to surrounding source/drain material (to create a p-n junction). The isolation schemes described herein enable neighboring active devices to retain strain in the nanowires/nanoribbons of their channel regions, thereby improving device performance.