A semiconductor device includes semiconductor wires or sheets disposed over a substrate, a source/drain epitaxial layer in contact with the semiconductor wires or sheets, a gate dielectric layer disposed on and wrapping around each channel region of the semiconductor wires or sheets, a gate electrode layer disposed on the gate dielectric layer and wrapping around each channel region, and insulating spacers disposed in spaces, respectively. The spaces are defined by adjacent semiconductor wires or sheets, the gate electrode layer and the source/drain region. The source/drain epitaxial layer includes multiple doped SiGe layers having different Ge contents and at least one of the source/drain epitaxial layers is non-doped SiGe or Si.

A method of making a vertical field effect transistor includes forming a semiconductor nanowire that extends from a substrate surface. A first sacrificial layer is deposited over the substrate surface, and a second sacrificial layer is deposited over the first sacrificial layer such that each of the first and second sacrificial layers are formed peripheral to the nanowire. The second sacrificial layer is then patterned to form a dummy gate structure. Thereafter, the first sacrificial layer is removed and source and drain regions are deposited via epitaxy directly over respective portions of the nanowire.

A method of fabricating a device includes forming a dummy gate over a plurality of fins. Thereafter, a first portion of the dummy gate is removed to form a first trench that exposes a first hybrid fin and a first part of a second hybrid fin. The method further includes filling the first trench with a dielectric material disposed over the first hybrid fin and over the first part of the second hybrid fin. Thereafter, a second portion of the dummy gate is removed to form a second trench and the second trench is filled with a metal layer. The method further includes etching-back the metal layer, where a first plane defined by a first top surface of the metal layer is disposed beneath a second plane defined by a second top surface of a second part of the second hybrid fin after the etching-back the metal layer.

A semiconductor device structure is provided. The semiconductor device structure includes a fin structure formed over a substrate, and a hard mask layer formed over the fin structure. The semiconductor device structure also includes a gate structure formed surrounding the hard mask layer and the fin structure, and a portion of the gate structure is interposed between the fin structure and the hard mask layer. The semiconductor device structure further includes a source/drain (S/D) structure formed adjacent to the gate structure.

A method and structure for suppressing band-to-band tunneling current in a semiconductor device having a high-mobility channel material includes forming a channel region adjacent to and in contact with one of a source region and a drain region. A tunnel barrier layer may be formed such that the tunnel barrier layer is interposed between, and in contact with, the channel region and one of the source region and the drain region. In some embodiments, a gate stack is then formed over at least the channel region. In various examples, the tunnel barrier layer includes a first material, and the channel region includes a second material different than the first material. In some embodiments, the semiconductor device may be oriented in one of a horizontal or vertical direction, and the semiconductor device may include one of a single-gate or multi-gate device.

A method is provided that may include providing a plurality of semiconductor pillars extending from a surface of a substrate, wherein a spacer is present on sidewall surfaces of each semiconductor pillar. A seed hole is then formed in a portion of each spacer that exposes a portion of at least one sidewall surface of each semiconductor pillar. Next, a semiconductor nanowire is epitaxially grown from the exposed portion of the at least one sidewall surface of each semiconductor pillar and entirely through each seed hole. A gate structure is then formed straddling over a channel portion of each semiconductor nanowire.

A semiconductor device structure is provided. The semiconductor device includes a first nanowire structure over a second nanowire structure, a gate stack wrapping around the first nanowire structure and the second nanowire structure, a source/drain feature adjoining the first nanowire structure and the second nanowire structure, a gate spacer layer over the first nanowire structure and between the gate stack and the source/drain feature, and an inner spacer layer between the first nanowire structure and the second nanowire structure and between the gate stack and the source/drain feature. The gate spacer layer has a first carbon concentration, the inner spacer has a second carbon concentration, and the second carbon concentration is lower than the first carbon concentration.

A method for manufacturing a semiconductor device includes forming a bottom source/drain region on a substrate, forming a semiconductor layer on the bottom source/drain region, patterning the semiconductor layer into a plurality of channel regions extending vertically with respect to the substrate, conformally forming a lower dielectric layer on the patterned semiconductor layer, forming a lower spacer layer on a portion of the lower dielectric layer, removing an exposed portion of the lower dielectric layer, forming a gate structure around the plurality of channel regions and on the lower spacer layer, and doping portions of the plurality of channel regions corresponding to the lower spacer layer, wherein the doping comprises diffusing a dopant from the lower dielectric layer into the portions of the plurality of channel regions.

A semiconductor device structure is provided. The semiconductor device structure includes a substrate. The semiconductor device structure includes a first nanostructure over the substrate. The semiconductor device structure includes a gate stack over the substrate and surrounding the first nanostructure. The semiconductor device structure includes a first source/drain layer surrounding the first nanostructure and adjacent to the gate stack. The semiconductor device structure includes a contact structure surrounding the first source/drain layer, wherein a first portion of the contact structure is between the first source/drain layer and the substrate.

A semiconductor device includes a first source/drain, a second source/drain isolated from direct contact with the first source/drain in a horizontal direction, a channel extending between the first source/drain and the second source/drain, a gate surrounding the channel, an upper inner spacer between the gate and the first source/drain and above the channel, and a lower inner spacer between the gate and the first source/drain and under the channel, in which the channel includes a base portion extending between the first source/drain and the second source/drain, an upper protrusion portion protruding upward from a top surface of the base portion, and a lower protrusion portion protruding downward from a bottom surface of the base portion, and a direction in which a top end of the upper protrusion portion is isolated from direct contact with a bottom end of the lower protrusion portion is oblique with respect to a vertical direction.