A method to form a semiconductor structure with an active region and a compatible dielectric layer is described. In one embodiment, a semiconductor structure has a dielectric layer comprised of an oxide of a first semiconductor material, wherein a second (and compositionally different) semiconductor material is formed between the dielectric layer and the first semiconductor material. In another embodiment, a portion of the second semiconductor material is replaced with a third semiconductor material in order to impart uniaxial strain to the lattice structure of the second semiconductor material.

A field effect transistor (FET) with an underlying airgap and methods of manufacture are disclosed. The method includes forming an amorphous layer at a predetermined depth of a substrate. The method further includes forming an airgap in the substrate under the amorphous layer. The method further includes forming a completely isolated transistor in an active region of the substrate, above the amorphous layer and the airgap.

A replacement channel and a method for forming the same in a semiconductor device are provided. A channel area is defined in a substrate which is a surface of a semiconductor wafer or a structure such as a fin formed over the wafer. Portions of the channel region are removed and are replaced with a replacement channel material formed by an epitaxial growth/deposition process to include a first dopant concentration level less than a first dopant concentration level. A subsequent doping operation or operations is then used to boost the average dopant concentration to a level greater than the first dopant concentration level. The replacement channel material is formed to include a gradient in which the upper portion of the replacement channel material has a greater dopant concentration than the lower portion of replacement channel material.

Some embodiments of the present disclosure provide a semiconductor structure, including a substrate having a top surface; a first doped region in proximity to the top surface; a non-doped region positioned in proximity to the top surface and adjacent to the first doped region, having a first width; a metal gate positioned over the non-doped region and over a portion of the first doped region, having a second width. The first width is smaller than the second width, and material constituting the non-doped region is different from material constituting the substrate.

Transistor structures having channel regions comprising alternating layers of compressively and tensilely strained epitaxial materials are provided. The alternating epitaxial layers can form channel regions in single and multigate transistor structures. In alternate embodiments, one of the two alternating layers is selectively etched away to form nanoribbons or nanowires of the remaining material. The resulting strained nanoribbons or nanowires form the channel regions of transistor structures. Also provided are computing devices comprising transistors comprising channel regions comprised of alternating compressively and tensilely strained epitaxial layers and computing devices comprising transistors comprising channel regions comprised of strained nanoribbons or nanowires.

A method of fabricating a MOSFET with an undoped channel is disclosed. The method comprises fabricating on a substrate a semiconductor structure having a dummy poly gate, dummy interlayer (IL) oxide, and a doped channel. The method further comprises removing the dummy poly gate and the dummy IL oxide to expose the doped channel, removing the doped channel from an area on the substrate, forming an undoped channel for the semiconductor structure at the area on the substrate, and forming a metal gate for the semiconductor structure. Removing the dummy poly gate may comprise dry and wet etch operations. Removing the dummy IL oxide may comprise dry etch operations. Removing the doped channel may comprise anisotropic etch operations on the substrate. Forming an undoped channel may comprise applying an epitaxial process to grow the undoped channel. The method may further comprise growing IL oxide above the undoped channel.

The present disclosure relates to a transistor device. In some embodiments, the transistor device has an epitaxial layer disposed over a substrate. The epitaxial layer is arranged between a source region and a drain region separated along a first direction. Isolation structures are arranged on opposite sides of the epitaxial layer along a second direction, perpendicular to the first direction. A gate dielectric layer is disposed over the epitaxial layer, and a conductive gate electrode is disposed over the gate dielectric layer. The epitaxial layer overlying the substrate improves the surface roughness of the substrate, thereby improving transistor device performance.

A method to form a semiconductor structure with an active region and a compatible dielectric layer is described. In one embodiment, a semiconductor structure has a dielectric layer comprised of an oxide of a first semiconductor material, wherein a second (and compositionally different) semiconductor material is formed between the dielectric layer and the first semiconductor material. In another embodiment, a portion of the second semiconductor material is replaced with a third semiconductor material in order to impart uniaxial strain to the lattice structure of the second semiconductor material.

Some embodiments of the present disclosure relate to a method. In this method, a semiconductor substrate, which has an active region disposed in the semiconductor substrate, is received. A shallow trench isolation (STI) structure is formed to laterally surround the active region. An upper surface of the active region bounded by the STI structure is recessed to below an upper surface of the STI structure. The recessed upper surface extends continuously between inner sidewalls of the STI structure and leaves upper portions of the inner sidewalls of the STI structure exposed. A semiconductor layer is epitaxially grown on the recessed surface of the active region between the inner sidewalls of the STI structure. A gate dielectric is formed over the epitaxially-grown semiconductor layer. A conductive gate electrode is formed over the gate dielectric.

A method of fabricating a field effect transistor (FET) includes forming a channel portion over a first surface of a substrate, wherein the channel portion comprises germanium and defines a second surface above the first surface. The method further includes forming cavities that extend through the channel portion and into the substrate. The method further includes epitaxially-growing a strained material in the cavities, wherein the strained material comprises SiGe, Ge, Si, SiC, GeSn, SiGeSn, SiSn or a III-V material.