A semiconductor device includes, above a substrate, a first layer with, on both sides in a direction, first regions; a second layer above the first layer with, on both sides in the direction, second regions above the first regions; a third layer, third regions, a fourth layer, and fourth regions, corresponding to the first layer, first regions, second layer, and second regions, respectively, the third layer being side by side with the first layer in another direction, the fourth layer being side by side with the second layer in the other direction; first and second gate electrodes above the first and second layers and the third and fourth layers, and having gate insulating films between these gate electrodes and these layers; and an insulating wall extending in the direction with both side surfaces contacted by the first and second layers and the third and fourth layers, respectively.

A method of microfabrication includes forming an initial stack of semiconductor layers by epitaxial growth over a substrate. The initial stack of semiconductor layers is surrounded by a sidewall structure. The initial stack of semiconductor layers includes channel structures and sacrificial gate layers stacked alternatingly in a vertical direction substantially perpendicular to a working surface of the substrate. The channel structures include a first channel structure and a second channel structure positioned above the first channel structure. First portions of the sidewall structure are removed to uncover first sides of the initial stack. Source/drain (S/D) regions are formed on uncovered side surfaces of the channel structures from the first sides of the initial stack. Second portions of the sidewall structure are removed to uncover second sides of the initial stack. The sacrificial gate layers are replaced with gate structures from the second sides of the initial stack.

Aspects of the present disclosure provide a method for fabricating a semiconductor structure. For example, the method can include forming a stack of metal structures on a substrate, the stack of metal structures including multiple metal structures that are vertically stacked over and electrically separated from one another, each of the metal structures including a ring and one or more pad contacts extending from the ring, the rings of the metal structures being vertically aligned with one another. The method can also include forming one or more channel structures within the rings of the metal structures, the channel structures being electrically separated from one another and electrically separated from the substrate. The method can also include forming one or more interconnections that extend from a position above the stack of metal structures to corresponding one or more of the pad contacts of the metal structures.

A device structure is disclosed. The device structure includes a channel region having a first surface facing an underlying substrate and a second surface opposite to the first surface. The device structure includes a gate at least partially surrounding the channel region. The gate includes a gate dielectric and a gate conductor, in which the gate dielectric separates the gate conductor from the channel region. The device structure includes self-aligned source and drain regions (S/D regions) contacting the first and second surfaces, respectively.

Stacked FET devices having wrap-around contacts to optimize contact resistance and techniques for formation thereof are provided. In one aspect, a stacked FET device includes: a bottom-level FET(s) on a substrate; lower contact vias present in an ILD disposed over the bottom-level FET(s); a top-level FET(s) present over the lower contact vias; and top-level FET source/drain contacts that wrap-around source/drain regions of the top-level FET(s), wherein the lower contact vias connect the top-level FET source/drain contacts to source/drain regions of the bottom-level FET(s). When not vertically aligned, a local interconnect can be used to connect a given one of the lower contact vias to a given one of the top-level FET source/drain contacts. A method of forming a stacked FET device is also provided.

A method for producing a 3D semiconductor device including: providing a first level, the first level including a first single crystal layer; forming first alignment marks and control circuits in and/or on the first level, where the control circuits include first single crystal transistors and at least two interconnection metal layers; forming at least one second level disposed above the control circuits; performing a first etch step into the second level; forming at least one third level disposed on top of the second level; performing additional processing steps to form first memory cells within the second level and second memory cells within the third level, where each of the first memory cells include at least one second transistor, where each of the second memory cells include at least one third transistor, performing bonding of the first level to the second level, where the bonding includes oxide to oxide bonding.

A semiconductor device includes an active region in a substrate, at least one nano-sheet on the substrate and spaced apart from a top surface of the active region, a gate above or below the nano-sheet, a gate insulating layer between the at least one nano-sheet and the gate, and source/drain regions on the active region at both sides of the at least one nano-sheet. The at least one nano-sheet includes a channel region; a gate disposed above or below the nano-sheet and including a single metal layer having different compositions of metal atoms of a surface and an inside thereof; a gate insulating layer between the nano-sheet and the gate; and source/drain regions disposed in the active region of both sides of the at least one nano-sheet.

Aspects of the present disclosure provide a method for forming a semiconductor structure having separated vertical channel structures. The method can include forming a layer stack on a substrate, the layer stack including alternating metal layers and dielectric layers. The method can further include forming vertically stacked lower and upper vertical channel structures vertically extending through the layer stack, the lower and upper vertical channel structures being separated by a sacrificial layer. The method can further include forming source, drain and gate connections to the lower and upper vertical channel structures, the source, drain and gate connections extending horizontally from the lower and upper vertical channel structures and then vertically to a location above the upper vertical channel structure. The method can further include forming a vertical opening in the layer stack and removing the sacrificial layer through the vertical opening to separate the lower and upper vertical channel structures.

Aspects of the present disclosure provide a multi-tier semiconductor structure. For example, the semiconductor structure can include a lower semiconductor device tier including lower semiconductor devices, an upper semiconductor device tier disposed over the lower semiconductor device tier and including upper semiconductor devices, a separation layer disposed between and separating the lower and upper semiconductor device tiers, a wiring tier disposed below the lower semiconductor device tier, a lower gate contact extending from a lower gate region of the lower semiconductor device tier downward to the wiring tier, an upper gate contact extending from an upper gate region of the upper semiconductor device tier downward through the separation layer to the wiring tier, and an isolator covering a lateral surface of the upper gate contact and electrically isolating the upper and lower gate contacts. The lower gate contact and the upper gate contact can be independent from each other.

Nanosheet transistor devices are provided. A nanosheet transistor device includes a transistor stack that includes a lower nanosheet transistor having a first nanosheet width and a lower gate width. The transistor stack also includes an upper nanosheet transistor that is on the lower nanosheet transistor and that has a second nanosheet width and an upper gate width that are different from the first nanosheet width and the lower gate width, respectively. Related methods of forming a nanosheet transistor device are also provided.