A method for forming a semiconductor structure is provided. The method includes forming a first active region in which first semiconductor layers and second semiconductor layers are alternatingly stacked over a first lower fin element. In a plan view, the active region includes a first portion and a second portion narrower than the first portion. The method also includes removing the first semiconductor layers of the first active region. The second semiconductor layers of the first portion of the first active region form first nanostructures, and the second semiconductor layers of the second portion of the first active region form second nanostructures. The method also includes forming a first gate stack to surround the first nanostructures, and forming a second gate stack to surround the second nanostructures.

A semiconductor apparatus may include a substrate including a first region and a second region; a first device on the first region; and a second device on the second region. The first device may include a channel structure including an insulating isolation pattern, first semiconductor patterns stacked under a lower surface of the insulating isolation pattern and including silicon germanium, and second semiconductor patterns stacked on an upper surface of the insulating isolation pattern and including silicon. The second device may include a semiconductor stack at a level corresponding to a level of the channel structure. The semiconductor stack may include an intermediate semiconductor layer, first lower semiconductor layers and second lower semiconductor layers alternately stacked under a lower surface of the intermediate semiconductor layer, and first upper semiconductor layers and second upper semiconductor layers alternately stacked on an upper surface of the intermediate semiconductor layer.

In a method of manufacturing a semiconductor device, a fin structure in which first semiconductor layers and second semiconductor layers are alternately stacked is formed over a substrate, a sacrificial gate structure is formed over the fin structure, a source/drain region of the fin structure is etched thereby forming a source/drain space, ends of the first semiconductor layers is laterally etched, an insulating layer is formed on a sidewall of the source/drain space, the insulating layer is partially etched, thereby forming one or more inner spacers on an etched end face of each of one or more first semiconductor layers and leaving a part of the insulating layer as a remaining insulating layer, and a source/drain epitaxial layer is formed in the source/drain space. After the source/drain epitaxial layer is formed, an end face of at least one of the second semiconductor layers is covered by the remaining insulating layer.

A device includes: a substrate having a semiconductor fin; a stack of semiconductor channels on the substrate and positioned over the fin; a gate structure wrapping around the semiconductor channels; a source/drain abutting the semiconductor channels; an inner spacer positioned between the stack of semiconductor channels and the fin; an undoped semiconductor layer vertically adjacent the source/drain and laterally adjacent the fin; and an isolation structure that laterally surrounds the undoped semiconductor layer, the isolation structure being between the source/drain and the inner spacer.

Semiconductor structures and methods of forming the same are provided. In an embodiment, an exemplary semiconductor structure includes a vertical stack of channel members disposed over a substrate, a gate structure wrapping around each channel member of the vertical stack of channel members, a dielectric feature disposed directly on the substrate and in direct contact with a portion of the vertical stack of channel members, and a source/drain feature disposed directly on the dielectric feature and electrically coupled to a remaining portion of the vertical stack of channel members.

A semiconductor structure includes a first stack of active channel layers and a second stack of active channel layers disposed over a semiconductor substrate, where the second stacking include a dummy channel layer and the first stack is free of any dummy channel layer, a gate structure engaged with the first stack and the second stack, and first S/D features disposed adjacent to the first stack and second S/D features disposed adjacent to the second stack, where the second S/D features overlap with the dummy channel layer.

Semiconductor structures and methods of forming the same are provided. In an embodiment, an exemplary semiconductor structure includes a first transistor. The first transistor includes a first gate structure wrapping around a plurality of first nanostructures disposed over a substrate, a first source/drain feature electrically coupled to a topmost nanostructure of the plurality of first nanostructures and isolated from a bottommost nanostructure of the plurality of first nanostructures by a first dielectric layer, and a first semiconductor layer disposed between the substrate and the first source/drain feature, wherein the first source/drain feature is in direct contact with a top surface of the first semiconductor layer.

Provided is a semiconductor device which includes: a substrate; a channel structure on the substrate; a source/drain pattern connected to the channel structure; a gate structure on the channel structure; an inner spacer structure comprising an inner spacer between the source/drain pattern and the gate structure, and an inner spacer residue connected to the inner spacer structure; and an inner isolation structure between the inner spacer residue and a bottom surface of the source/drain pattern.

A semiconductor device includes a semiconductor substrate. The semiconductor device further includes a fin protruding above the semiconductor substrate. The semiconductor device further includes a gate dielectric layer traversing a channel region of the fin. The semiconductor device further includes a gate structure including a gate dielectric layer traversing a channel region of the fin and a gate electrode disposed over the gate dielectric layer. The semiconductor device further includes a source region disposed in and over the fin. The semiconductor device further includes a drain region disposed in and over the fin. In some embodiments, the source region and the drain region are disposed on opposing sides of the gate structure.

A method includes forming Complementary Field-Effect Transistors including a lower transistor comprising a lower source/drain region, and an upper transistor including an upper source/drain region. An upper dielectric layer over the upper source/drain region and a lower dielectric layer under the upper source/drain region are etched to form an opening. A sidewall of the upper source/drain region and a top surface of the lower source/drain region are exposed to the opening. An epitaxy process is performed to form a first semiconductor layer on the sidewall of the upper source/drain region, and a second semiconductor layer on the top surface of the lower source/drain region. The first semiconductor layer is then removed, a contact plug is formed in the opening to electrically connects the upper source/drain region to the second semiconductor layer and the lower source/drain region.