A method includes forming a fin structure on the substrate, wherein the fin structure includes a first fin active region; a second fin active region; and an isolation feature separating the first and second fin active regions; forming a first gate stack on the first fin active region and a second gate stack on the second fin active region; performing a first recessing process to a first source/drain region of the first fin active region by a first dry etch; performing a first epitaxial growth to form a first source/drain feature on the first source/drain region; performing a fin sidewall pull back (FSWPB) process to remove a dielectric layer on the second fin active region; and performing a second epitaxial growth to form a second source/drain feature on a second source/drain region of the second fin active region.

Embodiments disclose a semiconductor structure and a fabrication method thereof. The method includes: providing a substrate; forming a stack structure on a surface of the substrate, where the stack structure includes a first semiconductor material layer and a first sacrificial layer alternately stacked from bottom to top; patterning and etching the stack structure and removing part of the first sacrificial layer to form a horizontal strip-shaped structure; forming a gate-all-around structure, where the gate-all-around structure covers part of a surface of the horizontal strip-shaped structure; and forming a bit line, where the bit line is formed in a same horizontal plane as the horizontal strip-shaped structure and the horizontal strip-shaped structure is segmented by the bit line, and the bit line is connected to a segmentation of the horizontal strip-shaped structure.

Techniques for improved extreme ultraviolet (EUV) patterning using assist features, related transistor structures, integrated circuits, and systems, are disclosed. A number of semiconductor fins and assist features are patterned into a semiconductor substrate using EUV. The assist features increase coverage of absorber material in the EUV mask, thereby reducing bright field defects in the EUV patterning. The semiconductor fins and assist features are buried in fill material and a mask is patterned that exposes the assist features and covers the semiconductor fins. The exposed assist features are partially removed and the protected active fins are ultimately used in transistor devices.

A semiconductor device includes a substrate. The semiconductor device includes a dielectric fin that is formed over the substrate and extends along a first direction. The semiconductor device includes a gate isolation structure vertically disposed above the dielectric fin. The semiconductor device includes a gate structure extending along a second direction perpendicular to the first direction. The gate structure includes a first portion and a second portion separated by the gate isolation structure and the dielectric fin. The first portion of the gate structure presents a first beak profile and the second portion of the gate structure presents a second beak profile. The first and second beak profiles point toward each other.

A semiconductor device includes a first semiconductor fin and a second semiconductor fin extending along a first direction. The semiconductor device includes a dielectric fin, extending along the first direction, that is disposed between the first and second semiconductor fins. The semiconductor device includes a gate isolation structure vertically disposed above the dielectric fin. The semiconductor device includes a metal gate layer extending along a second direction perpendicular to the first direction, wherein the metal gate layer includes a first portion straddling the first semiconductor fin and a second portion straddling the second semiconductor fin. The gate isolation structure has a central portion and one or more side portions, the central portion extends toward the dielectric fin a further distance than at least one of the one or more side portions.

A method includes forming a first semiconductor fin and a second semiconductor fin over a substrate that both extend along a first direction. The method includes forming a dielectric fin extending along the first direction and is disposed between the first and second semiconductor fins. The method includes forming a dummy gate structure extending along a second direction and straddling the first and second semiconductor fins and the dielectric fin. The method includes removing a portion of the dummy gate structure over the dielectric fin to form a trench by performing an etching process that includes a plurality of stages. Each of the plurality of stages includes a combination of anisotropic etching and isotropic etching such that a variation of a distance between respective inner sidewalls of the trench along the second direction is within a threshold.

A semiconductor device includes a first stack of nanowires above a substrate with a first gate structure over, around, and between the first stack of nanowires and a second stack of nanowires above the substrate with a second gate structure over, around, and between the second stack of nanowires. The device also includes a first source/drain region contacting a first number of nanowires of the first nanowire stack and a second source/drain region contacting a second number of nanowires of the second nanowire stack such that the first number and second number of contacted nanowires are different.

Techniques are disclosed for forming nanowire transistors employing carbon-based layers. Carbon is added to the sacrificial layers and/or non-sacrificial layers of a multilayer stack forming one or more nanowires in the transistor channel region. Such carbon-based layers reduce or prevent diffusion and intermixing of the sacrificial and non-sacrificial portions of the multilayer stack. The reduction of diffusion/intermixing can allow for the originally formed layers to effectively maintain their original thicknesses, thereby enabling the formation of relatively more nanowires for a given channel region height because of the more accurate processing scheme. The techniques can be used to benefit group IV semiconductor material nanowire devices (e.g., devices including Si, Ge, and/or SiGe) and can also assist with the selective etch processing used to form the nanowires. The carbon concentration of the sacrificial and/or non-sacrificial layers can be adjusted to facilitate etch process to liberate nanowires in the channel region.

Fin trim plug structures for imparting channel stress are described. In an example, an integrated circuit structure includes a fin including silicon, the fin having a top and sidewalls. The fin has a trench separating a first fin portion and a second fin portion. A first gate structure including a gate electrode is over the top of and laterally adjacent to the sidewalls of the first fin portion. A second gate structure including a gate electrode is over the top of and laterally adjacent to the sidewalls of the second fin portion. An isolation structure is in the trench of the fin, the isolation structure between the first gate structure and the second gate structure. The isolation structure includes a first dielectric material laterally surrounding a recessed second dielectric material distinct from the first dielectric material, the recessed second dielectric material laterally surrounding an oxidation catalyst layer.

A structure includes a semiconductor substrate including a first semiconductor region and a second semiconductor region, a first transistor in the first semiconductor region, and a second transistor in the second semiconductor region. The first transistor includes a first gate dielectric over the first semiconductor region, a first work function layer over and contacting the first gate dielectric, and a first conductive region over the first work function layer. The second transistor includes a second gate dielectric over the second semiconductor region, a second work function layer over and contacting the second gate dielectric, wherein the first work function layer and the second work function layer have different work functions, and a second conductive region over the second work function layer.