Semiconductor devices are provided. The semiconductor device includes an active fin which extends along a first direction and has a protruding shape, a gate structure which is disposed on the active fin to extend along a second direction intersecting the first direction, and a spacer which is disposed on at least one side of the gate structure, wherein the gate structure includes a first area and a second area which is adjacent to the first area in the second direction, wherein a first width of the first area in the first direction is different from a second width of the second area in the first direction, and the spacer extends continuously along both the first area and the second area.

Semiconductor devices having necked semiconductor bodies and methods of forming semiconductor bodies of varying width are described. For example, a semiconductor device includes a semiconductor body disposed above a substrate. A gate electrode stack is disposed over a portion of the semiconductor body to define a channel region in the semiconductor body under the gate electrode stack. Source and drain regions are defined in the semiconductor body on either side of the gate electrode stack. Sidewall spacers are disposed adjacent to the gate electrode stack and over only a portion of the source and drain regions. The portion of the source and drain regions under the sidewall spacers has a height and a width greater than a height and a width of the channel region of the semiconductor body.

Semiconductor devices having necked semiconductor bodies and methods of forming semiconductor bodies of varying width are described. For example, a semiconductor device includes a semiconductor body disposed above a substrate. A gate electrode stack is disposed over a portion of the semiconductor body to define a channel region in the semiconductor body under the gate electrode stack. Source and drain regions are defined in the semiconductor body on either side of the gate electrode stack. Sidewall spacers are disposed adjacent to the gate electrode stack and over only a portion of the source and drain regions. The portion of the source and drain regions under the sidewall spacers has a height and a width greater than a height and a width of the channel region of the semiconductor body.

A method for fabricating semiconductor device includes: forming a first semiconductor layer and an insulating layer on a substrate; removing the insulating layer and the first semiconductor layer to form openings; forming a second semiconductor layer in the openings; and patterning the second semiconductor layer, the insulating layer, and the first semiconductor layer to form fin-shaped structures.

A semiconductor device and a method of manufacturing a semiconductor device, the device including a first semiconductor pattern on a substrate, the first semiconductor pattern including a lower channel; a second semiconductor pattern on the first semiconductor pattern and spaced apart from the first semiconductor pattern in a vertical direction, the second semiconductor pattern including an upper channel extending in the vertical direction; a gate electrode covering the lower channel and surrounding the upper channel; and source/drain patterns on opposite sides of the upper channel, wherein the substrate and the first semiconductor pattern have a doping concentration of 10.sup.19/cm.sup.3 or less.

A method may include forming a dummy dielectric layer over a substrate, and forming a dummy gate over the dummy dielectric layer. The method may also include forming a first spacer adjacent the dummy gate, and removing the dummy gate to form a cavity, where the cavity is defined at least in part by the first spacer. The method may also include performing a plasma treatment on portions of the first spacer, where the plasma treatment causes a material composition of the portions of the first spacer to change from a first material composition to a second material composition. The method may also include etching the portions of the first spacer having the second material composition to remove the portions of the first spacer having the second material composition, and filling the cavity with conductive materials to form a gate structure.

An IC structure includes first, second, and third circuits. The first circuit includes a first semiconductor fin, a first gate electrode extending across the first semiconductor fin, and a first gate dielectric layer spacing the first gate electrode apart from the first semiconductor fin. The second circuit includes a second semiconductor fin, a second gate electrode extending across the second semiconductor fin, and a second gate dielectric layer spacing the second gate electrode apart from the second semiconductor fin. The third circuit includes a third semiconductor fin, a third gate electrode extending across the third semiconductor fin, and a third gate dielectric layer spacing the third gate electrode apart from the third semiconductor fin. The first gate dielectric layer has a greater thickness than the second gate dielectric layer. The third semiconductor fin has a smaller width than the second semiconductor fin.

Semiconductor devices having necked semiconductor bodies and methods of forming semiconductor bodies of varying width are described. For example, a semiconductor device includes a semiconductor body disposed above a substrate. A gate electrode stack is disposed over a portion of the semiconductor body to define a channel region in the semiconductor body under the gate electrode stack. Source and drain regions are defined in the semiconductor body on either side of the gate electrode stack. Sidewall spacers are disposed adjacent to the gate electrode stack and over only a portion of the source and drain regions. The portion of the source and drain regions under the sidewall spacers has a height and a width greater than a height and a width of the channel region of the semiconductor body.

An exemplary method includes receiving a hybrid fin device layout for a hybrid fin device that includes a gate disposed over a single-fin active region and a multi-fin active region. The single-fin active region and the multi-fin active region extend lengthwise along a first direction. The gate extends lengthwise along a second direction, the second direction is different than the first direction, and the gate has a width along the first direction. The single-fin active region and a first portion of the gate form a first fin-based device having a first electrical characteristic. The multi-fin active region and a second portion of the gate form a second fin-based device having a second electrical characteristic that is different than the first electrical characteristic. The method further includes tuning the width of the gate to reduce a difference between the first electrical characteristic and the second electrical characteristic.

In a method of manufacturing a semiconductor device a fin structure is formed in which first semiconductor layers and second semiconductor layers are alternately stacked over a substrate. A sacrificial gate structure is formed over the fin structure. A source/drain region of the fin structure that is not covered by the sacrificial gate structure is etched to form a source/drain space. An isolation region is formed at a bottom portion of the source/drain space. A source/drain epitaxial layer is formed over the isolation region in the source/drain space, and a void region in the isolation region is produced between the source/drain epitaxial layer and the substrate to cause electrical isolation between the source/drain region and the substrate.