A semiconductor structure includes a stacked device structure having a first field-effect transistor having a first source/drain region, and a second field-effect transistor vertically stacked above the first field-effect transistor, the second field-effect transistor having a second source/drain region and a gate region having first sidewall spacers. The stacked device structure further includes a frontside source/drain contact disposed on a first portion of a sidewall and a top surface of the second source/drain region, a first metal via connected to the frontside source/drain contact and to a first backside power line, and second sidewall spacers disposed on a first portion of the first metal via. The first sidewall spacers comprise a first dielectric material and the second sidewall spacers comprise a second dielectric material different than the first dielectric material.

Forces applied to the channel regions of semiconductor slabs in a first direction relative to the semiconductor slab, can create strains in the crystal structure that improve carrier mobility to improve drive strength in the channel region. In a three-dimensional (3D) FET structure, a work function metal layer is provided on opposing faces of semiconductor slabs to cause a force to be exerted on the channel regions in a first direction corresponding to current flow. The force in the first direction is either tensile force or compressive force, depending on a FET type (N or P) employing the semiconductor slab, and is provided to create strain in a crystalline structure of the semiconductor slab to improve carrier mobility in the channel region. Increasing carrier mobility in the channel regions in a 3D FET structure increases drive strength of the 3D FET, which saves area in an integrated circuit.

A method includes forming a fin structure including a first channel layer, a sacrificial layer, and a second channel layer over a substrate; forming a dummy gate structure across the fin structure; recessing the fin structure; epitaxially growing first source/drain epitaxial structures on opposite sides of the first channel layer; forming first dielectric layers to cover the first source/drain epitaxial structures, respectively; epitaxially growing second source/drain epitaxial structures on opposite sides of the second channel layer; removing the dummy gate structure and the sacrificial layer to form a gate trench between the first source/drain epitaxial structures and between the second source/drain epitaxial structures; and forming a metal gate structure in the gate trench. The second source/drain epitaxial structures are over the first dielectric layers, respectively.

Semiconductor structures and methods are provided. A semiconductor structure according to the present disclosure includes a semiconductor substrate, a high-Kappa dielectric layer disposed on the semiconductor substrate, a first plurality of nanostructures disposed over the high-Kappa dielectric layer, a middle dielectric layer disposed over the first plurality of nanostructures, a second plurality of nanostructures over the middle dielectric layer, a first gate structure wrapping around the first plurality of nanostructures, a second gate structure wrapping around the second plurality of nanostructures. The high-Kappa dielectric layer includes metal nitride, metal oxide, silicon carbide, graphene, or diamond.

Semiconductor structures and methods of forming the same are provided. An exemplary method includes depositing a contact etch stop layer (CESL) and an interlayer dielectric (ILD) layer over a bottom epitaxial source/drain feature formed in a bottom portion of a source/drain trench, etching back the CESL and the ILD layer to expose a top portion of the source/drain trench, performing a plasma-enhanced atomic layer deposition process (PEALD) to form an insulating layer over the source/drain trench, where the insulating layer comprises a non-uniform deposition thickness and comprises a first portion in direct contact with the ILD layer and a second portion extending along a sidewall surface of the top portion of the source/drain trench. Method also includes removing the second portion of the insulating layer and forming a top bottom epitaxial source/drain feature on the second portion of the insulating layer and in the source/drain trench.

A method for manufacturing a semiconductor structure includes: forming a channel portion on a fin portion; forming two source/drain portions on the fin portion and at two opposite sides of the channel portion, in which each of the two source/drain portions includes a first semiconductor material that is doped with dopant impurities; and forming two bottom portions each of which is disposed between the fin portion and a corresponding one of the two source/drain portions, in which each of the two bottom portions includes a second semiconductor material that is different from the first semiconductor material and that is capable of trapping the dopant impurities when the dopant impurities in the first semiconductor material diffuse toward the fin portion.

A semiconductor structure is provided that includes a first stacked FET cell including a second FET stacked over a first FET, and a second stacked FET cell located adjacent to the first stacked FET cell and including a fourth FET stacked over a third FET. The structure further includes a first backside source/drain contact structure located beneath the first stacked FET cell and contacting a source/drain region of the first FET, a second backside source/drain contact structure located beneath the second stacked FET cell and contacting a source/drain region of the third FET, and an angled cut region laterally separating the first backside source/drain contact structure from the second backside source/drain contact structure.

A method for manufacturing a semiconductor device including an upper-channel implant transistor is provided. The method includes forming one or more fins extending in a first direction over a substrate. The one or more fins include a first region along the first direction and second regions on both sides of the first region along the first direction. A dopant is shallowly implanted in an upper portion of the first region of the fins but not in the second regions and not in a lower portion of the first region of the fins. A gate structure extending in a second direction perpendicular to the first direction is formed overlying the first region of the fins, and source/drains are formed overlying the second regions of the fins, thereby forming an upper-channel implant transistor.

Methods for improving profiles of channel regions in semiconductor devices and semiconductor devices formed by the same are disclosed. In an embodiment, a method includes forming a semiconductor fin over a semiconductor substrate, the semiconductor fin including germanium, a germanium concentration of a first portion of the semiconductor fin being greater than a germanium concentration of a second portion of the semiconductor fin, a first distance between the first portion and a major surface of the semiconductor substrate being less than a second distance between the second portion and the major surface of the semiconductor substrate; and trimming the semiconductor fin, the first portion of the semiconductor fin being trimmed at a greater rate than the second portion of the semiconductor fin.

A nano-FET and a method of forming is provided. In some embodiments, a nano-FET includes an epitaxial source/drain region contacting ends of a first nanostructure and a second nanostructure. The epitaxial source/drain region may include a first semiconductor material layer of a first semiconductor material, such that the first semiconductor material layer includes a first segment contacting the first nanostructure and a second segment contacting the second nanostructure, wherein the first segment is separated from the second segment. A second semiconductor material layer is formed over the first segment and the second segment. The second semiconductor material layer may include a second semiconductor material having a higher concentration of dopants of a first conductivity type than the first semiconductor material layer. The second semiconductor material layer may have a lower concentration percentage of silicon than the first semiconductor material layer.