The present disclosure describes a semiconductor device and methods for forming the same. The semiconductor device includes nanostructures on a substrate and a source/drain region in contact with the nanostructures. The source/drain region includes epitaxial end caps, where each epitaxial end cap is formed at an end portion of a nanostructure of the nanostructures. The source/drain region also includes an epitaxial body in contact with the epitaxial end caps and an epitaxial top cap formed on the epitaxial body. The semiconductor device further includes gate structure formed on the nanostructures.

A method includes forming a first and a second contact opening to reveal a first and a second source/drain region, respectively, forming a mask layer having a first and a second portion in the first and the second contact openings, respectively, forming a first and a second sacrificial ILD in the first and the second contact openings, respectively, removing the first sacrificial ILD from the first contact opening, filling a filler in the first contact opening, and etching the second sacrificial ILD. The filler protects the first portion of the mask layer from being etched. An ILD is formed in the second contact opening and on the second portion of the mask layer. The filler and the first portion of the mask layer are removed using a wet etch to reveal the first contact opening. A contact plug is formed in the first contact opening.

Gate-all-around integrated circuit structures having embedded GeSnB source or drain structures, and methods of fabricating gate-all-around integrated circuit structures having embedded GeSnB source or drain structures, are described. For example, an integrated circuit structure includes a vertical arrangement of horizontal nanowires above a fin, the fin including a defect modification layer on a first semiconductor layer, and a second semiconductor layer on the defect modification layer. A gate stack is around the vertical arrangement of horizontal nanowires. A first epitaxial source or drain structure is at a first end of the vertical arrangement of horizontal nanowires, and a second epitaxial source or drain structure is at a second end of the vertical arrangement of horizontal nanowires.

In an embodiment, a method of forming a semiconductor device includes forming a fin protruding above a substrate; forming a gate structure over the fin; forming a recess in the fin and adjacent to the gate structure; performing a wet etch process to clean the recess; treating the recess with a plasma process; and performing a dry etch process to clean the recess after the plasma process and the wet etch process.

A method for manufacturing a semiconductor structure includes forming a fin over a substrate, wherein the fin includes first semiconductor layers and second semiconductor layers alternating stacked. The method also includes forming an isolation feature around the fin, forming a dielectric feature over the isolation feature, forming a cap layer over the fin and the dielectric feature, oxidizing the cap layer to form an oxidized cap layer, forming source/drain features passing through the cap layer and in the fin, removing the second semiconductor layers in the fin to form nanostructures, and forming a gate structure wrapping around the nanostructures.

A method includes providing a substrate, an isolation structure, a semiconductor fin having a stack of first and second semiconductor layers, a dummy gate, and outer spacers on opposing sidewalls of the dummy gate; etching the semiconductor fin to form source/drain (S/D) trenches; etching the second semiconductor layers from the S/D trenches to form gaps vertically between the first semiconductor layers; forming inner spacers in the gaps; epitaxially growing S/D features in the S/D trenches; forming an inter-layer dielectric layer over the S/D features; etching the dummy gate and the outer spacers to form a gate-end trench away from the semiconductor fin and over the isolation structure; and forming a gate-end dielectric feature filling the gate-end trench, wherein a dielectric constant of the gate-end dielectric feature is higher than both a dielectric constant of the outer spacers and a dielectric constant of the inner spacers.

The present disclosure describes a method of fabricating a semiconductor structure that includes forming a fin structure on a substrate, forming a polysilicon gate structure on a first portion of the fin structure, forming an opening in a second portion of the fin structure, wherein the first and second portions of the fin structure is adjacent to each other, forming a recess laterally on a sidewall of the first portion of the fin structure underlying the polysilicon gate structure, and forming an inner spacer structure within the recess. The inner spacer structure comprises an inner air spacer enclosed by a first dielectric spacer layer and a second dielectric spacer layer.

A first gate structure, a second gate structure, and a third gate structure each extend in a first direction. A first gate via is disposed on the first gate structure. The first gate via has a first size. A second gate via is disposed on the second gate structure. The second gate via has a second size that is greater than the first size. A third gate via is disposed on the third gate structure. The third gate via has a third size that is less than the second size but greater than the first size. A first source contact is disposed adjacent to a first side of the first gate via. A first drain contact is disposed adjacent to a second side of the first gate via opposite the first side. A second drain contact is disposed adjacent to a first side of the third gate via.

A method for manufacturing a semiconductor device includes forming a plurality of semiconductor layers on a semiconductor substrate, and forming a plurality of gate structures spaced apart from each other on the semiconductor layers. The semiconductor layers are patterned into a plurality of patterned stacks spaced apart from each other, wherein the plurality of patterned stacks are under the plurality of gate structures. The method also includes forming a plurality of sacrificial spacers on lateral sides of the plurality of gate structures, and growing a plurality of source/drain regions. The source/drain regions are adjacent the patterned stacks and include a plurality of pillar portions formed on lateral sides of the sacrificial spacers. The sacrificial spacers and the plurality of pillar portions are removed.

A semiconductor structure includes a first semiconductor substrate, a second semiconductor substrate, a depletion layer, an isolation structure, a first gate structure, and a second gate structure. The first and second semiconductor substrates respectively have a first active region and a second active region overlapping the first active region. The depletion layer is disposed between the first active region and the second active region. The isolation structure surrounds the first and second active regions. The first gate structure is disposed in the second active region. The second gate structure is disposed in the second active region. The second active region has a portion between the first gate structure and the second gate structure.