A method of fabricating a device includes providing a fin having a stack of epitaxial layers including a plurality of semiconductor channel layers interposed by a plurality of dummy layers. A source/drain etch process is performed to remove portions of the stack of epitaxial layers in source/drain regions to form trenches that expose lateral surfaces of the stack of epitaxial layers. A dummy layer recess process is performed to laterally etch the plurality of dummy layers to form recesses along sidewalls of the trenches. An inner spacer material is deposited along sidewalls of the trenches and within the recesses. An inner spacer etch-back process is performed to remove the inner spacer material from the sidewalls of the trenches and to remove a portion of the inner spacer material from within the recesses to form inner spacers having a dish-like region along lateral surfaces of the inner spacers.

A semiconductor device includes a fin protruding from a substrate and extending in a first direction, a gate structure extending on the fin in a second direction, and a seal layer located on the sidewall of the gate structure. A first peak carbon concentration is disposed in the seal layer. A first spacer layer is located on the seal layer. A second peak carbon concentration is disposed in the first spacer layer. A second spacer layer is located on the first spacer layer.

A semiconductor structure and a method for preparing a semiconductor structure are provided. The method for preparing the semiconductor structure includes operations as follows. A substrate is provided, and a plurality of gate structures are arranged at intervals on the substrate. A sacrificial sidewall with a preset thickness is formed on a sidewall of the gate structure. A first dielectric layer is formed between adjacent sacrificial sidewalls, a top of the first dielectric layer being flush with a top of the gate structure and a top of the sacrificial sidewalls. The sacrificial sidewall is removed and an air gap structure is formed on the sidewall of the gate structure. A second dielectric layer is formed, the second dielectric layer covering the top of the gate structure, a top opening of the air gap structure and the top of the first dielectric layer.

A semiconductor device structure is provided. The semiconductor device structure includes a substrate having a base and a fin over the base. The semiconductor device structure includes a gate stack over a top portion of the fin. The semiconductor device structure includes a first nanostructure over the fin and passing through the gate stack. The semiconductor device structure includes a second nanostructure over the first nanostructure and passing through the gate stack. The first nanostructure is thicker than the second nanostructure. The semiconductor device structure includes a stressor structure over the fin and connected to the first nanostructure and the second nanostructure.

Semiconductor devices are provided. A semiconductor device includes a substrate. The semiconductor device includes a stack structure on the substrate. The stack structure includes a first insulating material and a second insulating material that is on the first insulating material. The semiconductor device includes a spacer that extends from a sidewall of the first insulating material of the stack structure to a portion of a sidewall of the second insulating material of the stack structure. Moreover, the semiconductor device includes a conductive line that is on the spacer. Methods of forming semiconductor devices are also provided.

A method of forming a semiconductor device that includes forming a trench adjacent to a gate structure to expose a contact surface of one of a source region and a drain region. A sacrificial spacer may be formed on a sidewall of the trench and on a sidewall of the gate structure. A metal contact may then be formed in the trench to at least one of the source region and the drain region. The metal contact has a base width that is less than an upper surface width of the metal contact. The sacrificial spacer may be removed, and a substantially conformal dielectric material layer can be formed on sidewalls of the metal contact and the gate structure. Portions of the conformally dielectric material layer contact one another at a pinch off region to form an air gap between the metal contact and the gate structure.

The structure of a semiconductor device with negative capacitance (NC) dielectric structures and a method of fabricating the semiconductor device are disclosed. A method of fabricating the semiconductor device includes forming a fin structure with a fin base portion and a fin top portion on a substrate, forming a spacer structure in a first region of the fin top portion, and forming a gate structure on a second region of the fin top portion. The spacer structure includes a first NC dielectric material and the gate structure includes a gate dielectric layer with a second NC dielectric material different from the first NC dielectric material.

A semiconductor device includes a semiconductor substrate, a first semiconductor stack, a second semiconductor stack, a first gate structure, and a second gate structure. The semiconductor substrate comprising a first device region and a second device region. The first semiconductor stack is located on the semiconductor substrate over the first device region, and has first channels. The second semiconductor stack is located on the semiconductor substrate over the second device region, and has second channels. A total number of the first channels is greater than a total number of the second channels. The first gate structure encloses the first semiconductor stack. The second gate structure encloses the second semiconductor stack.

The present application discloses a semiconductor device including a substrate; a first semiconductor stack having a first threshold voltage and comprising a first insulating stack positioned on the substrate; a second semiconductor stack having a second threshold voltage and comprising a second insulating stack positioned on the substrate; and wherein the first threshold voltage is different the second threshold voltage; a thickness of the first insulating stack is different from a thickness of the second insulating stack.

Techniques and mechanisms to impose stress on a transistor which includes a channel region and a source or drain region each in a fin structure. In an embodiment, a gate structure of the transistor extends over the fin structure, wherein a first spacer portion is at a sidewall of the gate structure and a second spacer portion adjoins the first spacer portion. Either or both of two features are present at or under respective bottom edges of the spacer portions. One of the features includes a line of discontinuity on the fin structure. The other feature includes a concentration of a dopant in the second spacer portion being greater than a concentration of the dopant in the source or drain region. In another embodiment, the fin structure is disposed on a buffer layer, wherein stress on the channel region is imposed at least in part with the buffer layer.