A field effect transistor includes a source region and a drain region formed within and/or above openings in a dielectric capping mask layer overlying a semiconductor substrate and a gate electrode. A source-side silicide portion and a drain-side silicide portion are self-aligned to the source region and to the drain region, respectively.

Embodiments include Multiple Gate Field-Effect Transistors (MuGFETs) and methods of forming them. In an embodiment, a structure includes a substrate, a fin, masking dielectric layer portions, and a raised epitaxial lightly doped source/drain (LDD) region. The substrate includes the fin. The masking dielectric layer portions are along sidewalls of the fin. An upper portion of the fin protrudes from the masking dielectric layer portions. A first spacer is along a sidewall of a gate structure over a channel region of the fin. A second spacer is along the first spacer. The raised epitaxial LDD region is on the upper portion of the fin, and the raised epitaxial LDD region adjoins a sidewall of the first spacer and is disposed under the second spacer. The raised epitaxial LDD region extends from the upper portion of the fin in at least two laterally opposed directions and a vertical direction.

In some embodiments, the present disclosure relates to a semiconductor device comprising a source and drain region arranged within a substrate. A conductive gate is disposed over a doped region of the substrate. A gate dielectric layer is disposed between the source region and the drain region and separates the conductive gate from the doped region. A bottommost surface of the gate dielectric layer is below a topmost surface of the substrate. First and second sidewall spacers are arranged along first and second sides of the conductive gate, respectively. An inner portion of the first sidewall spacer and an inner portion of the second sidewall spacer respectively cover a first and second top surface of the gate dielectric layer. A drain extension region and a source extension region respectively separate the drain region and the source region from the gate dielectric layer.

A semiconductor structure includes a semiconductor substrate, a trench being provided in the semiconductor substrate, and a gate being formed in the trench; an ion implantation layer located in the semiconductor substrate outside the trench, a top surface of the ion implantation layer being higher than that of the gate, and a bottom surface of the ion implantation layer being lower than the top surface of the gate and higher than a bottom surface of the gate; a transition layer located between the gate and the ion implantation layer, a bottom surface of the transition layer being lower than the top surface of the gate and higher than the bottom surface of the gate, and a doping concentration of the transition layer being lower than that of the ion implantation layer.

A includes depositing a gate electrode layer over a semiconductor substrate; patterning the gate electrode layer into a first gate electrode and a gate electrode extending portion; forming a first gate spacer alongside the first gate electrode; patterning the gate electrode extending portion into a second gate electrode after forming the first gate spacer; and forming a second gate spacer alongside the second gate electrode and a third gate spacer around the first spacer.

The present disclosure provides a semiconductor device structure in accordance with some embodiments. In some embodiments, the semiconductor device structure includes a semiconductor substrate of a first semiconductor material and having first recesses. The semiconductor device structure further includes a first gate stack formed on the semiconductor substrate and being adjacent the first recesses. In some examples, a passivation material layer of a second semiconductor material is formed in the first recesses. In some embodiments, first source and drain (S/D) features of a third semiconductor material are formed in the first recesses and are separated from the semiconductor substrate by the passivation material layer. In some cases, the passivation material layer is free of chlorine.

A method includes: forming a gate over a semiconductor substrate; forming doped regions in the semiconductor substrate; depositing a dielectric layer on sidewalls of the gate, the dielectric layer including vertical portions laterally surrounding a sidewall of the gate; depositing a spacer laterally surrounding the dielectric layer, the spacer including a carbon-free portion laterally surrounding the vertical portions of the dielectric layer and a carbon-containing portion laterally surrounding the carbon-free portion; forming source/drain regions in the semiconductor substrate; performing an etching operation to remove the gate and vertical portions of the dielectric layer using the carbon-free portion as an etching stop layer to thereby expose the carbon-free portion and form a recess; and forming a gate dielectric layer and a conductive layer in the recess, wherein the gate dielectric layer extends in at least a portion of an area where the vertical portions of the dielectric layer are etched.

A semiconductor substrate has a surface and a convex portion projecting upward from the surface. An n-type drift region has a portion located in the convex portion. The n.sup.−-type drain region has a higher n-type impurity concentration than the n-type drift region, and is arranged in the convex portion and on the n-type drift region such that the n.sup.−-type drain region and a gate electrode sandwich the n-type drift region in plan view.

A method for fabricating semiconductor device includes the steps of: forming a fin-shaped structure on a substrate; forming a gate dielectric layer on the fin-shaped structure; forming a gate electrode on the fin-shaped structure; performing a nitridation process to implant ions into the gate dielectric layer adjacent to two sides of the gate electrode; and forming an epitaxial layer adjacent to two sides of the gate electrode.

A construction of integrated circuitry comprises a trench isolation region in semiconductive material. The trench isolation region comprises laterally-opposing laterally-outermost first regions which comprise a first material and a second region laterally-inward of the first regions. The second region comprises a second material of different composition from that of the first material. A diffusion region is in the uppermost portion of the semiconductive material directly against a sidewall of one of the first regions. Insulator material is above the trench isolation region and the diffusion region. An elevationally-elongated conductive via is in the insulator material and extends to the diffusion region and the trench isolation region. The conductive via laterally overlaps the diffusion region and the one first region. The conductive via is directly against a top surface of the diffusion region, is directly against an upper portion of a sidewall of the diffusion region, and is directly against a laterally-outer sidewall of the second material of the second region of the trench isolation material. Other embodiments, including method, are disclosed.