Semiconductor devices with airgap spacers and methods of forming the same include forming a lower spacer that defines a gate region. A sacrificial upper spacer is formed directly above the lower spacer. A gate stack is formed in the gate region. The sacrificial upper spacer is etched away to form an upper spacer opening. An airgap spacer is formed in the upper spacer opening. The airgap spacer includes a dielectric material that encapsulates an internal void.

A semiconductor structure and a method for forming the same are provided. The semiconductor structure includes a gate stack structure formed over a substrate. The gate stack structure includes a gate electrode structure having a first portion and a second portion and a first conductive layer below the gate electrode structure. In addition, the first portion of the gate electrode structure is located over the second portion of the gate electrode structure, and a width of a top surface of the first portion of the gate electrode structure is greater than a width of a bottom surface of the second portion of the gate electrode structure.

After forming a sacrificial gate structure straddling a stacking of a semiconductor mandrel structure and a dielectric mandrel cap and spacers present on sidewalls of the stack, portions of the spacers located on opposite sides of the sacrificial gate structure are removed. Epitaxial source/drain regions are formed on exposed sidewalls of portions of the semiconductor mandrel structure located on opposite sides of the sacrificial gate structure. The sacrificial gate structure is removed to provide a gate cavity. Next, portions of the spacers exposed by the gate cavity are removed to expose sidewalls of a portion of the semiconductor mandrel structure. III-V compound semiconductor channel portions are then formed on exposed sidewalls of the semiconductor mandrel structure. Portions of the semiconductor mandrel structure and the dielectric mandrel cap exposed by the gate cavity are subsequently removed from the structure, leaving only the III-V compound semiconductor channel portions.

A method of forming a semiconductor device that includes forming a strain relaxed buffer (SRB) layer atop a supporting substrate, and epitaxially forming a tensile semiconductor material atop a first portion of the strain relaxed buffer layer (SRB) layer. A second portion of the SRB layer is then removed, and a semiconductor material including a base material of silicon and phosphorus is formed atop a surface of the supporting substrate exposed by removing the second portion of the SRB layer. A compressive semiconductor material is epitaxially forming atop the semiconductor material including the base material of silicon and phosphorus. Compressive FinFET structures can then be formed from the compressive semiconductor material and tensile FinFET structures can then be formed from the tensile semiconductor material.

Aspects of the present disclosure include fabricating integrated circuit (IC) structures using a boron etch-stop layer, and IC structures with a boron-rich region therein. Methods of forming an IC structure according to the present disclosure can include: growing a conductive epitaxial layer on an upper surface of a semiconductor element; forming a boron etch-stop layer directly on an upper surface of the conductive epitaxial layer; forming an insulator on the boron etch-stop layer; forming an opening within the insulator to expose an upper surface of the boron etch-stop layer; annealing the boron etch-stop layer to drive boron into the conductive epitaxial layer, such that the boron etch-stop layer becomes a boron-rich region; and forming a contact to the boron-rich region within the opening, such that the contact is electrically connected to the semiconductor element through at least the conductive epitaxial layer.

A method of fabricating a semiconductor device comprises providing a substrate with a shallow trench isolation (STI) within the substrate and a gate stack. A cavity is formed between the gate stack and the STI. The cavity comprises one sidewall formed by the STI, one sidewall formed by the substrate, and a bottom surface formed by the substrate. A film is grown in the cavity and thereafter an opening formed by removing a first portion of the strained film until exposing the bottom surface of the substrate while a second portion of the strained film adjoins the STI sidewall. Another epitaxial layer is then grown in the opening.

A device includes a substrate and insulation regions over a portion of the substrate. A first semiconductor region is between the insulation regions and having a first conduction band. A second semiconductor region is over and adjoining the first semiconductor region, wherein the second semiconductor region includes an upper portion higher than top surfaces of the insulation regions to form a semiconductor fin. The semiconductor fin has a tensile strain and has a second conduction band lower than the first conduction band. A third semiconductor region is over and adjoining a top surface and sidewalls of the semiconductor fin, wherein the third semiconductor region has a third conduction band higher than the second conduction band.

A semiconductor device may include: a semiconductor substrate, a device isolating layer embedded within the semiconductor substrate and defining an active region, a channel region formed in the active region, a gate electrode disposed above the channel region, a gate insulating layer provided between the channel region and the gate electrode, and a silicon germanium epitaxial layer adjacent to the channel region within the active region and including a first epitaxial layer containing a first concentration of germanium, a second epitaxial layer containing a second concentration of germanium, higher than the first concentration, and a third epitaxial layer containing a third concentration of germanium, lower than the second concentration, the first to third epitaxial layers being sequentially stacked on one another in that order.

A method includes forming a gate, a first dielectric layer, a first contact structure, and a second contact structure over a substrate. The first contact structure and the second contact structure are over a source region and a drain region respectively. The first dielectric layer surrounds the gate, the first contact structure, and the second contact structure. The method includes forming a second dielectric layer over the first dielectric layer. The second dielectric layer has an opening exposing the gate, the first contact structure, and the second contact structure. A conductive layer is formed in the opening to electrically connect the gate to the first contact structure and the second contact structure.

Semiconductor devices are provided. A semiconductor device includes a substrate. The semiconductor device includes an isolation layer defining active portions of the substrate that are spaced apart from each other in a direction. The semiconductor device includes an epitaxial layer on the active portions. The semiconductor device includes a metal silicide layer on the epitaxial layer. Moreover, the semiconductor device includes a contact structure that only partially overlaps the metal silicide layer on the epitaxial layer. Related methods of forming semiconductor devices are also provided.