The present disclosure relates to semiconductor structures and, more particularly, to cavity structures under shallow trench isolation regions and methods of manufacture. The structure includes: one or more cavity structures provided in a substrate material and sealed with an epitaxial material; and a shallow trench isolation region directly above the one or more cavity structures in the substrate material.

Disclosed is a semiconductor device for improving a gate induced drain leakage and a method for fabricating the same, and the method may include forming a trench in a substrate, lining a surface of the trench with an initial gate dielectric layer, forming a gate electrode to partially fill the lined trench, forming a sacrificial material spaced apart from a top surface of the gate electrode and to selectively cover a top corner of the lined trench, removing a part of the initial gate dielectric layer of the lined trench which is exposed by the sacrificial material in order to form an air gap, and forming a capping layer to cap a side surface of the air gap, over the gate electrode.

Semiconductor devices and methods are provided to fabricate FET devices. For example, a semiconductor device can include a functional gate structure on a channel region of a fin structure; and a source/drain region on each side of the functional gate structure. The functional gate structure has an insulator material abutting a portion of the sidewalls of the functional gate structure and the source drain region and the top surface of the fin. The functional gate structure further includes a dielectric top layer. The dielectric top layer seals an air gap between the top surface of the insulator material and the dielectric top layer.

A device is disclosed. The device includes a gate conductor, a first source-drain region and a second source-drain region. The device includes a first air gap space between the first source-drain region and a first side of the gate conductor and a second air gap space between the second source-drain region and a second side of the gate conductor. A hard mask layer that includes holes is under the gate conductor, the first source-drain region, the second source-drain region and the air gap spaces. A planar dielectric layer is under the hard mask.

A semiconductor device and a method of forming the same are provided. The method includes forming a sacrificial gate structure over an active region. A first spacer layer is formed along sidewalls and a top surface of the sacrificial gate structure. A first protection layer is formed over the first spacer layer. A second spacer layer is formed over the first protection layer. A third spacer layer is formed over the second spacer layer. The sacrificial gate structure is replaced with a replacement gate structure. The second spacer layer is removed to form an air gap between the first protection layer and the third spacer layer.

A method for forming a gaseous spacer in a semiconductor device and a semiconductor device including the gaseous spacer are disclosed. In an embodiment, the method may include forming a gate stack over a substrate, depositing a first gate spacer on sidewalls of the gate stack, epitaxially growing source/drain regions on opposite sides of the gate stack, and depositing a second gate spacer over the first gate spacer to form a gaseous spacer below the second gate spacer. The gaseous spacer may be disposed laterally between the source/drain regions and the gate stack.

A semiconductor device includes a gate having a gate spacer formed on a semiconductor substrate and a source or drain (S/D) formed on the substrate a distance away from the gate. A S/D contact including a contact spacer is formed on an upper surface of the S/D. A dielectric layer is interposed between the gate spacer and the contact spacer; and an airgap is in the dielectric layer.

A method includes forming a gate stack over a semiconductor region, and forming a first gate spacer on a sidewall of the gate stack. The first gate spacer includes an inner sidewall spacer, and a dummy spacer portion on an outer side of the inner sidewall spacer. The method further includes removing the dummy spacer portion to form a trench, and forming a dielectric layer to seal a portion of the trench as an air gap. The air gap and the inner sidewall spacer in combination form a second gate spacer. A source/drain region is formed to have a portion on an outer side of the second gate spacer.

The present disclosure provides a method of fabricating a semiconductor structure in accordance with some embodiments. The method includes receiving a substrate having an active region and an isolation region; forming gate stacks on the substrate and extending from the active region to the isolation region; forming an inner gate spacer and an outer gate spacer on sidewalls of the gate stacks; forming an interlevel dielectric (ILD) layer on the substrate; removing the outer gate spacer in the isolation region, resulting in an air gap between the inner gate spacer and the ILD layer; and performing an ion implantation process to the ILD layer, thereby expanding the ILD layer to cap the air gap.

A semiconductor structure is provided in which an L-shaped airgap spacer is located between a functional gate structure and a source/drain contact structure. The L-shaped airgap spacer is sandwiched between a lower dielectric material spacer that is L-shaped and an upper dielectric material spacer that is also L-shaped.