A method for fabricating a semiconductor device includes the steps of first forming a gate dielectric layer on a substrate, forming a gate material layer on the gate dielectric layer, patterning the gate material layer and the gate dielectric layer to form a gate structure, removing a portion of the gate dielectric layer, forming a spacer adjacent to the gate structure and at the same time forming an air gap between the gate dielectric layer and the spacer, and then forming a source/drain region adjacent to two sides of the spacer.

A method for fabricating a semiconductor device includes the steps of first forming a gate dielectric layer on a substrate, forming a gate material layer on the gate dielectric layer, patterning the gate material layer and the gate dielectric layer to form a gate structure, removing a portion of the gate dielectric layer, forming a spacer adjacent to the gate structure and at the same time forming an air gap between the gate dielectric layer and the spacer, and then forming a source/drain region adjacent to two sides of the spacer.

The present disclosure provides a semiconductor structure. The semiconductor structure includes a substrate having an active region and an isolation region. The semiconductor structure includes gate stacks on the substrate that extend over the active region and the isolation region. The semiconductor structure includes a gate spacer on sidewalls of the gate stacks. The semiconductor structure includes an interlevel dielectric (ILD) layer over the substrate and implanted with one or more dopants, the ILD layer having a top implanted portion over a bottom nonimplanted portion. The top implanted portion seals an air gap between a sidewall of the ILD layer and the gate spacer.

A method for manufacturing a semiconductor structure includes forming a first dielectric layer on a gate structure and a source drain structure. A recess is formed at least partially in the first dielectric layer. A protection layer is formed at least on a sidewall of the recess. The recess is deepened to expose the source drain structure. A bottom conductor is formed in the recess and is electrically connected to the source drain structure. The protection layer is removed to form a gap between the bottom conductor and the sidewall of the recess.

A semiconductor device that includes a gate structure on a channel region of a semiconductor device. Source and drain regions may be present on opposing sides of the channel region. The semiconductor device may further include a composite gate sidewall spacer present on a sidewall of the gate structure. The composite gate sidewall spacer may include a first composition portion having an air gap encapsulated therein, and a second composition portion that is entirely solid and present atop the first composition portion.

A semiconductor device includes an isolation layer, first and second fin structures, a gate structure and a source/drain structure. The isolation layer is disposed over a substrate. The first and second fin structures are disposed over the substrate, and extend in a first direction in plan view. Upper portions of the first and second fin structures are exposed from the isolation layer. The gate structure is disposed over parts of the first and second fin structures, and extends in a second direction crossing the first direction. The source/drain structure is formed on the upper portions of the first and second fin structures, which are not covered by the first gate structure and exposed from the isolation layer, and wraps side surfaces and a top surface of each of the exposed first and second fin structures. A void is formed between the source/drain structure and the isolation layer.

A semiconductor device that includes a gate structure on a channel region of a semiconductor device. Source and drain regions may be present on opposing sides of the channel region. The semiconductor device may further include a composite gate sidewall spacer present on a sidewall of the gate structure. The composite gate sidewall spacer may include a first composition portion having an air gap encapsulated therein, and a second composition portion that is entirely solid and present atop the first composition portion.

A semiconductor device includes an isolation layer, first and second fin structures, a gate structure and a source/drain structure. The isolation layer is disposed over a substrate. The first and second fin structures are disposed over the substrate, and extend in a first direction in plan view. Upper portions of the first and second fin structures are exposed from the isolation layer. The gate structure is disposed over parts of the first and second fin structures, and extends in a second direction crossing the first direction. The source/drain structure is formed on the upper portions of the first and second fin structures, which are not covered by the first gate structure and exposed from the isolation layer, and wraps side surfaces and a top surface of each of the exposed first and second fin structures. A void is formed between the source/drain structure and the isolation layer.

An electrical circuit comprising at least two negative capacitance insulators connected in series, one of the two negative capacitance insulators is biased to generate a negative capacitance. One of the negative capacitance insulators may include an air-gap which is part of a nanoelectromechnical system (NEMS) device and the second negative capacitance insulator includes a ferroelectric material. Both of the negative capacitance insulators may be located between the channel and gate of a field effect transistor. The NEMS device may include a movable electrode, a dielectric and a fixed electrode and arranged so that the movable electrode is attached to at least two points and spaced apart from the dielectric and fixed electrode, and the ferroelectric capacitor is electrically connected to either of the electrodes.

A semiconductor device that includes a gate structure on a channel region of a semiconductor device. Source and drain regions may be present on opposing sides of the channel region. The semiconductor device may further include a composite gate sidewall spacer present on a sidewall of the gate structure. The composite gate sidewall spacer may include a first composition portion having an air gap encapsulated therein, and a second composition portion that is entirely solid and present atop the first composition portion.