A semiconductor device includes a substrate; two source/drain (S/D) regions over the substrate; a gate stack over the substrate and between the two S/D regions; a spacer layer covering sidewalls of the gate stack; an S/D contact metal over one of the two S/D regions; a first dielectric layer covering sidewalls of the S/D contact metal; and an inter-layer dielectric (ILD) layer covering the first dielectric layer, the spacer layer, and the gate stack, thereby defining a gap. A material of a first sidewall of the gap is different from materials of a top surface and a bottom surface of the gap, and a material of a second sidewall of the gap is different from the materials of the top surface and the bottom surface of the gap.

Transistors having partially recessed gates are constructed on silicon-on-insulator (SOI) semiconductor wafers provided with a buried oxide layer (BOX), for example, FD-SOI and UTBB devices. An epitaxially grown channel region relaxes constraints on the design of doped source and drain profiles. Formation of a partially recessed gate and raised epitaxial source and drain regions allow further improvements in transistor performance and reduction of short channel effects such as drain induced barrier lowering (DIBL) and control of a characteristic subthreshold slope. Gate recess can be varied to place the channel at different depths relative to the dopant profile, assisted by advanced process control. The partially recessed gate has an associated high-k gate dielectric that is initially formed in contact with three sides of the gate. Subsequent removal of the high-k sidewalls and substitution of a lower-k silicon nitride encapsulant lowers capacitance between the gate and the source and drain regions.

A method includes forming a dummy gate stack, forming a dielectric layer, with the dummy gate stack located in the dielectric layer, removing the dummy gate stack to form a opening in the dielectric layer, forming a metal layer extending into the opening, and etching back the metal layer. The remaining portions of the metal layer in the opening have edges lower than a top surface of the dielectric layer. A conductive layer is selectively deposited in the opening. The conductive layer is over the metal layer, and the metal layer and the conductive layer in combination form a replacement gate.

In fabricating metal-oxide-semiconductor field-effect transistors (MOSFETs), the implanting of lightly doped drain regions is performed before forming gate regions with a physical gate length that is associated with a reference channel length. The step of implanting lightly doped drain regions includes forming an implantation mask defining the lightly doped drain regions and an effective channel length of each MOSFET. The forming of the implantation mask is configured to define an effective channel length of at least one MOSFET that is different from the respective reference channel length.

A method includes forming a dummy gate stack, forming a dielectric layer, with the dummy gate stack located in the dielectric layer, removing the dummy gate stack to form a opening in the dielectric layer, forming a metal layer extending into the opening, and etching back the metal layer. The remaining portions of the metal layer in the opening have edges lower than a top surface of the dielectric layer. A conductive layer is selectively deposited in the opening. The conductive layer is over the metal layer, and the metal layer and the conductive layer in combination form a replacement gate.

Partial self-aligned contact structures are provided. In one aspect, a method of forming a semiconductor device includes: patterning fins in a substrate; forming a gate(s) over the fins, separated from source/drains by first spacers, wherein a lower portion of the gate(s) includes a workfunction-setting metal, and an upper portion of the gate(s) includes a core metal between a metal liner; recessing the metal liner to form divots in the upper portion of the gate(s) in between the first spacers and the core metal; forming second spacers in the divots such that the first spacers and the second spacers surround the core metal in the upper portion of the gate(s); forming lower source/drain contacts in between the first spacers over the source/drains; recessing the lower source/drain contacts to form gaps over the lower source/drain contacts; and forming source/drain caps in the gaps. A semiconductor device is also provided.

Partial self-aligned contact structures are provided. In one aspect, a method of forming a semiconductor device includes: patterning fins in a substrate; forming a gate(s) over the fins, separated from source/drains by first spacers, wherein a lower portion of the gate(s) includes a workfunction-setting metal, and an upper portion of the gate(s) includes a core metal between a metal liner; recessing the metal liner to form divots in the upper portion of the gate(s) in between the first spacers and the core metal; forming second spacers in the divots such that the first spacers and the second spacers surround the core metal in the upper portion of the gate(s); forming lower source/drain contacts in between the first spacers over the source/drains; recessing the lower source/drain contacts to form gaps over the lower source/drain contacts; and forming source/drain caps in the gaps. A semiconductor device is also provided.

A structure for a field-effect transistor includes a semiconductor body, a first gate structure extending over the semiconductor body, and a second gate structure extending over the semiconductor body. A recess is in the semiconductor body between the first and second gate structures. A three part source/drain region includes a pair of spaced semiconductor spacers in the recess; a first semiconductor layer laterally between the pair of semiconductor spacers; and a second semiconductor layer over the first semiconductor layer. The pair of spaced semiconductor spacers, the first semiconductor layer and the second semiconductor layer may all have different dopant concentrations.

A semiconductor component including: a semiconductor substrate; and a semiconductor device provided thereon, the device being a field-effect transistor that includes: a gate insulating film provided on the substrate; a gate electrode provided via the film; and a pair of source-drain regions provided to sandwich the electrode, the substrate including a patterned surface in a portion where the electrode is provided, the patterned surface of the substrate including a raised portion where the film is formed to cover a surface that lies on the same plane as a surface of the pair of source-drain regions, and the electrode is formed on a top surface of the film, and the patterned surface of the substrate including a recessed portion where the film is formed to cover surfaces of a groove formed toward the interior than the surface of the pair of source-drain regions, and the electrode is formed so as to fill the groove provided with the film.

A semiconductor device includes a substrate; two source/drain (S/D) regions over the substrate; a gate stack over the substrate and between the two S/D regions; a spacer layer covering sidewalls of the gate stack; an S/D contact metal over one of the two S/D regions; a first dielectric layer covering sidewalls of the S/D contact metal; and an inter-layer dielectric (ILD) layer covering the first dielectric layer, the spacer layer, and the gate stack, thereby defining a gap. A material of a first sidewall of the gap is different from materials of a top surface and a bottom surface of the gap, and a material of a second sidewall of the gap is different from the materials of the top surface and the bottom surface of the gap.