Provided is a semiconductor device and a method of manufacturing the semiconductor device. The semiconductor device includes: a 1.sup.st source/drain region connected to a 1.sup.st channel structure; a 2.sup.nd source/drain region, above the 1.sup.st source/drain region, connected to a 2.sup.nd channel structure above the 1.sup.st channel structure; a backside contact structure on a bottom surface of the 1.sup.st source/drain region; and a backside isolation structure surrounding the backside contact structure, wherein the bottom surface of the 1.sup.st source/drain region is at a level below a top surface of the backside isolation structure.

Semiconductor device structures and methods for manufacturing the same are provided. A semiconductor device structure is provided. The semiconductor device structure includes an isolation structure formed over a substrate, and first nanostructures formed over the isolation structure along a first direction. The semiconductor device structure includes a first gate structure formed over the first nanostructures along a second direction, and a first dielectric structure formed adjacent to the first nanostructures along the first direction. The first dielectric structure is in direct contact with the first nanostructures. The semiconductor device structure includes a second gate structure formed adjacent to the first gate structure, and the second gate structure is formed directly over the first dielectric structure.

Structures and methods are disclosed in which a layer stack can be formed with a plurality of layers of a metal, where each of the layers of metal can be separated by a layer of a dielectric. An opening in the layer stack can be formed such that a semiconductor layer beneath the plurality of layers of the metal is uncovered. One or more vertical channel structures can be formed within the opening by epitaxial growth. The vertical channel structure can include a vertically oriented transistor. The vertical channel structure can include an interface of a silicide metal with a first metal layer of the plurality of metal layers. The interface can correspond to one of a source or a drain connection of a transistor. The silicide metal can be annealed above a temperature threshold to form a silicide interface between the vertical channel structure and the first metal layer.

Multi-gate devices and methods for fabricating such are disclosed herein. An exemplary method includes forming a semiconductor stack on a substrate, wherein the semiconductor stack includes a first semiconductor layers and a second semiconductor layers alternatively disposed, the first semiconductor layers and the second semiconductor layers being different in composition; patterning the semiconductor stack to form a semiconductor fin; forming a dielectric fin next to the semiconductor fin; forming a first gate stack on the semiconductor fin and the dielectric fin; etching to a portion of the semiconductor fin within a source/drain region, resulting in a source/drain recess; and epitaxially growing a source/drain feature in the source/drain recess, defining an airgap spanning between a sidewall of the source/drain feature and a sidewall of the dielectric fin.

A method includes forming a gate stack, growing a source/drain region on a side of the gate stack through epitaxy, depositing a contact etch stop layer (CESL) over the source/drain region, depositing an inter-layer dielectric over the CESL, etching the inter-layer dielectric and the CESL to form a contact opening, and etching the source/drain region so that the contact opening extends into the source/drain region. The method further includes depositing a metal layer extending into the contact opening. Horizontal portions, vertical portions, and corner portions of the metal layer have a substantially uniform thickness. An annealing process is performed to react the metal layer with the source/drain region to form a source/drain silicide region. The contact opening is filled to form a source/drain contact plug.

A multi-finger transistor structure is provided in the present invention, including multiple active areas, a gate structure consisting of multiple gate parts and connecting parts, wherein each gate part crosses over one of the active areas and each connecting part alternatively connects one end and the other end of the gate parts so as to form a meander gate structure, and multiple sources and drains, wherein one source and one drain are set between two adjacent gate parts, and each gate parts is accompanied by one source and one drain at two sides respectively, and the distance between the drain and the gate part is larger than the distance between the source and the gate part, so that the source and the drain are asymmetric with respect to the corresponding gate part, and air gaps are formed in the dielectric layer between each drain and the corresponding gate part.

Memory cells, semiconductor devices, semiconductor stacked structures, and fabrication methods are provided. An example memory cell includes a capacitor and a transistor stacked over the capacitor in a compact configuration. The capacitor includes a floating gate, a high-k dielectric layer, and a metal gate. The metal gate extends horizontally from a first sidewall to a second sidewall and vertically from a bottom surface to a top surface. The transistor includes the metal gate and a gate dielectric layer disposed on the metal gate. The gate dielectric layer includes two side portions respectively disposed on the two sidewalls of the metal gate and, and a top portion disposed on the top surface of the metal gate. The transistor further includes two separate S/D regions respectively formed on the two side portions of the gate dielectric layer, and a channel region formed on the top portion of the gate dielectric layer.

An exemplary method includes forming an opening in an interlevel dielectric (ILD) layer. The opening in the ILD layer exposes a doped epitaxial layer. The method further includes performing an in-situ doping deposition process, an annealing process, and an etching process to form a doped semiconductor layer over the doped epitaxial layer. The doped semiconductor layer partially fills the opening. The method further includes forming a metal-comprising structure that fills a remainder of the opening. The metal-comprising structure is disposed over a top and sidewalls of the doped epitaxial layer. The doped semiconductor layer is disposed between the metal-comprising structure and the top of the doped epitaxial layer and between the metal-comprising structure and the sidewalls of the doped epitaxial layer. The in-situ deposition process may implement a temperature less than about 350 C. The doped epitaxial layer includes p-type dopant (e.g., boron), and the doped semiconductor layer includes gallium.

The present disclosure provides a method of manufacturing a semiconductor device. The method includes forming a stack of first semiconductor layers and second semiconductor layers over a substrate, etching the stack to form a source/drain (S/D) recess in exposing the substrate, and forming an S/D formation assistance region in the S/D recess. The S/D formation assistance region is partially embedded in the substrate and includes a semiconductor seed layer embedded in an isolation layer. The isolation layer electrically isolates the semiconductor seed layer from the substrate. The method also includes epitaxially growing an S/D feature in the S/D recess from the semiconductor seed layer. The S/D feature is in physical contact with the second semiconductor layers.

A gate insulating film and a gate electrode of non-single crystalline silicon for forming an nMOS transistor are provided on a silicon substrate. Using the gate electrode as a mask, n-type dopants having a relatively large mass number (70 or more) such as As ions or Sb ions are implanted, to form a source/drain region of the nMOS transistor, whereby the gate electrode is amorphized. Subsequently, a silicon oxide film is provided to cover the gate electrode, at a temperature which is less than the one at which recrystallization of the gate electrode occurs. Thereafter, thermal processing is performed at a temperature of about 1000 C., whereby high compressive residual stress is exerted on the gate electrode, and high tensile stress is applied to a channel region under the gate electrode. As a result, carrier mobility of the nMOS transistor is enhanced.