Embodiments herein describe techniques, systems, and method for a semiconductor device. A semiconductor device may include isolation areas above a substrate to form a trench between the isolation areas. A first buffer layer is over the substrate, in contact with the substrate, and within the trench. A second buffer layer is within the trench over the first buffer layer, and in contact with the first buffer layer. A channel area is above the first buffer layer, above a portion of the second buffer layer that are below a source area or a drain area, and without being vertically above a portion of the second buffer layer. In addition, the source area or the drain area is above the second buffer layer, in contact with the second buffer layer, and adjacent to the channel area. Other embodiments may be described and/or claimed.

A method for forming a gate-all-around structure is provided. The method includes forming a plurality of a first type of semiconductor layers and a plurality of a second type of semiconductor layers alternately stacked over a fin. The first type of semiconductor layers includes a first semiconductor layer and a second semiconductor layer, and the first semiconductor layer has a thickness greater than that of the second semiconductor layer. The method also includes removing the second type of semiconductor layers. In addition, the method includes forming a gate to wrap around the first type of semiconductor layers.

Embodiments disclosed herein include semiconductor devices and methods of making semiconductor devices. In an embodiment, a semiconductor device comprises a substrate, where the substrate is a dielectric material, and a vertical stack of semiconductor channels over the substrate. In an embodiment, the semiconductor device further comprises a source at a first end of the semiconductor channels, a drain at a second end of the semiconductor channels, and a barrier between a bottom surface of the source and the substrate.

Gate-all-around integrated circuit structures having nanoribbon sub-fin isolation by backside Si substrate removal etch selective to source and drain epitaxy, are described. For example, an integrated circuit structure includes a plurality of horizontal nanowires above a sub-fin. A gate stack is over the plurality of nanowires and the sub-fin. Epitaxial source or drain structures are on opposite ends of the plurality of horizontal nanowires; and a doped nucleation layer at a base of the epitaxial source or drain structures adjacent to the sub-fin. Where the integrated circuit structure comprises an NMOS transistor, doped nucleation layer comprises a carbon-doped nucleation layer. Where the integrated circuit structure comprises a PMOS transistor, doped nucleation layer comprises a heavy boron-doped nucleation layer.

A semiconductor structure includes: a channel layer; an active layer over the channel layer, wherein the active layer is configured to form a two-dimensional electron gas (2DEG) to be formed in the channel layer along an interface between the channel layer and the active layer; a gate electrode over a top surface of the active layer; and a source/drain electrode over the top surface of the active layer; wherein the active layer includes a first layer and a second layer sequentially disposed therein from the top surface to a bottom surface of the active layer, and the first layer possesses a higher aluminum (Al) atom concentration compared to the second layer. An HEMT structure and an associated method are also disclosed.

The present disclosure describes a method for the formation of gate-all-around nano-sheet FETs with tunable performance. The method includes disposing a first and a second vertical structure with different widths over a substrate, where the first and the second vertical structures have a top portion comprising a multilayer nano-sheet stack with alternating first and second nano-sheet layers. The method also includes disposing a sacrificial gate structure over the top portion of the first and second vertical structures; depositing an isolation layer over the first and second vertical structures so that the isolation layer surrounds a sidewall of the sacrificial gate structure; etching the sacrificial gate structure to expose each multilayer nano-sheet stack from the first and second vertical structures; removing the second nano-sheet layers from each exposed multilayer nano-sheet stack to form suspended first nano-sheet layers; forming a metal gate structure to surround the suspended first nano-sheet layers.

Embodiments herein describe techniques for a semiconductor device over a semiconductor substrate. A first bonding layer is above the semiconductor substrate. One or more nanowires are formed above the first bonding layer to be a channel layer. A gate electrode is around a nanowire, where the gate electrode is in contact with the first bonding layer and separated from the nanowire by a gate dielectric layer. A source electrode or a drain electrode is in contact with the nanowire, above a bonding area of a second bonding layer, and separated from the gate electrode by a spacer, where the second bonding layer is above and in direct contact with the first bonding layer.

A semiconductor device includes a first source/drain region and a second source/drain region disposed on opposite sides of a plurality of conductive layers. A dielectric layer overlies the first source/drain region, the second source/drain region, and the plurality of conductive layers. An electrical contact extends through the dielectric layer and the first source/drain region, where a first surface of the electrical contact is a surface of the electrical contact that is closest to the substrate, a first surface of the plurality of conductive layers is a surface of the plurality of conductive layers that is closest to the substrate, and the first surface of the electrical contact is closer to the substrate than the first surface of the plurality of conductive layers.

Gate-all-around integrated circuit structures having depopulated channel structures, and methods of fabricating gate-all-around integrated circuit structures having depopulated channel structures using a backside removal approach, are described. For example, an integrated circuit structure includes a first insulator sub-fin structure over a first stack of nanowires. A second insulator sub-fin structure is over a second stack of nanowires, the second stack of nanowires having a greater number of nanowires than the first stack of nanowires, and the second insulator sub-fin structure having a vertical thickness less than a vertical thickness of the first insulator sub-fin structure. A first gate electrode is around the first stack of nanowires, and a second gate electrode is around the second stack of nanowires.

Fin cuts in neighboring gate and source or drain regions for advanced integrated circuit structure fabrication is described. For example, an integrated circuit structure includes a horizontal stack of semiconductor nanowire portions. A dielectric gate spacer is vertically over the horizontal stack of semiconductor nanowire portions. A gate isolation structure is laterally adjacent to a first side of the horizontal stack of semiconductor nanowire portions. A source or drain isolation structure is laterally adjacent to a second side of the horizontal stack of semiconductor nanowire portions.