Embodiments of the present invention are directed to methods and resulting structures for nanosheet devices having defect free channels. In a non-limiting embodiment of the invention, a nanosheet stack is formed over a substrate. The nanosheet stack includes alternating first sacrificial layers and second sacrificial layers. One layer of the first sacrificial layers has a greater thickness than the remaining first sacrificial layers. The first sacrificial layers are removed and semiconductor layers are formed on surfaces of the second sacrificial layers. The semiconductor layers include a first set and a second set of semiconductor layers. The second sacrificial layers are removed and an isolation dielectric is formed between the first set and the second set of semiconductor layers.

Non-planar semiconductor devices having doped sub-fin regions and methods of fabricating non-planar semiconductor devices having doped sub-fin regions are described. For example, a method of fabricating a semiconductor structure involves forming a plurality of semiconductor fins above a semiconductor substrate. A solid state dopant source layer is formed above the semiconductor substrate, conformal with the plurality of semiconductor fins. A dielectric layer is formed above the solid state dopant source layer. The dielectric layer and the solid state dopant source layer are recessed to approximately a same level below a top surface of the plurality of semiconductor fins, exposing protruding portions of each of the plurality of semiconductor fins above sub-fin regions of each of the plurality of semiconductor fins. The method also involves driving dopants from the solid state dopant source layer into the sub-fin regions of each of the plurality of semiconductor fins.

A semiconductor device includes a channel pattern including a first semiconductor pattern and a second semiconductor pattern, which are sequentially stacked on a substrate, and a gate electrode that extends in a first direction and crosses the channel pattern. The gate electrode includes a first portion interposed between the substrate and the first semiconductor pattern and a second portion interposed between the first and second semiconductor patterns. A maximum width in a second direction of the first portion is greater than a maximum width in the second direction of the second portion, and a maximum length in the second direction of the second semiconductor pattern is less than a maximum length in the second direction of the first semiconductor pattern.

A semiconductor device includes a substrate; a fin protruding above the substrate, the fin including a compound semiconductor material that includes a semiconductor material and a first dopant, the first dopant having a different lattice constant than the semiconductor material, where a concentration of the first dopant in the fin changes along a first direction from an upper surface of the fin toward the substrate; a gate structure over the fin; a channel region in the fin and directly under the gate structure; and source/drain regions on opposing sides of the gate structure, the source/drain regions including a second dopant, where a concentration of the second dopant at a first location within the channel region is higher than that at a second location within the channel region, where the concentration of the first dopant at the first location is lower than that at the second location.

A semiconductor device includes a semiconductor substrate, a first semiconductor stack, a second semiconductor stack, a first gate structure, and a second gate structure. The semiconductor substrate comprising a first device region and a second device region. The first semiconductor stack is located on the semiconductor substrate over the first device region, and has first channels. The second semiconductor stack is located on the semiconductor substrate over the second device region, and has second channels. A total number of the first channels is greater than a total number of the second channels. The first gate structure encloses the first semiconductor stack. The second gate structure encloses the second semiconductor stack.

A mask layer is formed over a semiconductor device. The semiconductor device includes: a gate structure, a first layer disposed over the gate structure, and an interlayer dielectric (ILD) disposed on sidewalls of the first layer. The mask layer includes an opening that exposes a portion of the first layer and a portion of the ILD. A first etching process is performed to etch the opening partially into the first layer and partially into the ILD. A liner layer is formed in the opening after the first etching process has been performed. A second etching process is performed after the liner layer has been formed. The second etching process extends the opening downwardly through the first layer and through the gate structure. The opening is filled with a second layer after the second etching process has been performed.

An integrated circuit device includes a fin-type active area along a first horizontal direction on a substrate, a device isolation layer on opposite sidewalls of the fin-type active area, a gate structure along a second horizontal direction crossing the first horizontal direction, the gate structure being on the fin-type active area and on the device isolation layer, and a source/drain area on the fin-type active area, the source/drain area being adjacent to the gate structure, and including an outer blocking layer, an inner blocking layer, and a main body layer sequentially stacked on the fin-type active area, and each of the outer blocking layer and the main body layer including a Si1-xGex layer, where x≠0, and the inner blocking layer including a Si layer.

A semiconductor device includes an active pattern on a substrate, a source/drain pattern on the active pattern, a channel pattern connected to the source/drain pattern, the channel pattern including semiconductor patterns stacked and spaced apart from each other, a gate electrode extending across the channel pattern, and inner spacers between the gate electrode and the source/drain pattern. The semiconductor patterns include stacked first and second semiconductor patterns. The gate electrode includes first and second portions, which are sequentially stacked between the substrate and the first and second semiconductor patterns, respectively. The inner spacers include first and second air gaps, between the first and second portions of the gate electrode and the source/drain pattern. The largest width of the first air gap is larger than that of the second air gap.

A semiconductor device includes an active pattern on a substrate, the active pattern extending in a first direction parallel to an upper surface of the substrate, a gate structure on the active pattern, the gate structure extending in a second direction parallel to the upper surface of the substrate and crossing the first direction, channels spaced apart from each other in a third direction perpendicular to the upper surface of the substrate, each of the channels extending through the gate structure, a source/drain layer on a portion of the active pattern adjacent the gate structure, the source/drain layer contacting the channels, and a sacrificial pattern on an upper surface of each of opposite edges of the portion of the active pattern in the second direction, the sacrificial pattern contacting a lower portion of a sidewall of the source/drain layer and including silicon-germanium.

A device includes a first vertical stack of nanostructures over a substrate, a second vertical stack of nanostructures over the substrate, a wall structure between and in direct contact with the first and second vertical stacks, a gate structure wrapping around three sides of the nanostructures and a source/drain region beside the first vertical stack of nanostructures.