Multi-gate devices and methods for fabricating such are disclosed herein. An exemplary method includes forming a gate dielectric layer around first channel layers in a p-type gate region and around second channel layers in an n-type gate region. Sacrificial features are formed between the second channel layers in the n-type gate region. A p-type work function layer is formed over the gate dielectric layer in the p-type gate region and the n-type gate region. After removing the p-type work function layer from the n-type gate region, the sacrificial features are removed from between the second channel layers in the n-type gate region. An n-type work function layer is formed over the gate dielectric layer in the n-type gate region. A metal fill layer is formed over the p-type work function layer in the p-type gate region and the n-type work function layer in the n-type gate region.

A semiconductor device includes: an active fin disposed on a substrate; a gate structure overlapping the active fin; source/drain regions disposed on both sides of the gate structure and on the active fin; and contact structures respectively connected to the source/drain regions, wherein the gate structure includes: a pair of gate spacers spaced apart from each other to provide a trench; a first gate electrode disposed in the trench and extending along an upper surface and a lateral surface of the active fin; a second gate electrode disposed on the first gate electrode in the trench, wherein the first gate electrode is not disposed between the second gate electrode and the pair of gate spacers; and a gate insulating film disposed between the pair of gate spacers and interposed between the first gate electrode and the active fin.

Embodiments of mechanisms for forming dislocations in source and drain regions of finFET devices are provided. The mechanisms involve recessing fins and removing the dielectric material in the isolation structures neighboring fins to increase epitaxial regions for dislocation formation. The mechanisms also involve performing a pre-amorphous implantation (PAI) process either before or after the epitaxial growth in the recessed source and drain regions. An anneal process after the PAI process enables consistent growth of the dislocations in the source and drain regions. The dislocations in the source and drain regions (or stressor regions) can form consistently to produce targeted strain in the source and drain regions to improve carrier mobility and device performance for NMOS devices.

A method includes depositing a first dielectric layer over and along sidewalls of a first semiconductor fin and a second semiconductor fin, depositing a second dielectric layer over the first dielectric layer, recessing the first dielectric layer to define a dummy fin between the first semiconductor fin and the second semiconductor fin, forming a cap layer over top surfaces and sidewalls of the first semiconductor fin and the second semiconductor fin, wherein the forming the cap layer comprises depositing the cap layer in a furnace at process temperatures higher than a first temperature, and lowering the temperature of the furnace, wherein during the lowering the temperature of the furnace, the pressure in the furnace is raised to and maintained at 10 torr or higher until the temperature of the furnace drops below the first temperature.

A semiconductor device structure is provided. The semiconductor device structure includes a first stacked nanostructure and a second stacked nanostructure formed over a substrate. The semiconductor device structure includes a first gate structure formed over the first stacked nanostructure, and the first gate structure includes a first portion of a gate dielectric layer and a first portion of a filling layer. The semiconductor device structure includes a second gate structure formed over the second stacked nanostructure, and the second gate structure includes a second portion of the gate dielectric layer and a second portion of the filling layer. The semiconductor device structure includes a first isolation layer between the first gate structure and the second gate structure, wherein the first isolation layer has an extending portion which is formed in a recess between the gate dielectric layer and the filling layer.

A semiconductor structure includes a substrate, a semiconductor fin protruding from the substrate, where the semiconductor fin includes semiconductor layers stacked in a vertical direction, a gate stack engaging with channel regions of the semiconductor fin, and source/drain (S/D) features disposed adjacent to the gate stack in S/D regions of the semiconductor fin. In the present embodiments, the gate stack includes a first portion disposed over the semiconductor layers and a second portion disposed between the semiconductor layers, where the first portion includes a work-function metal (WFM) layer and a metal fill layer disposed over the WFM layer and the second portion includes the WFM layer but is free of the metal fill layer.

A substrate is patterned to form trenches and a semiconductor fin between the trenches. Insulators are formed in the trenches and a first dielectric layer is formed to cover the semiconductor fin and the insulators. A dummy gate strip is formed on the first dielectric layer. Spacers are formed on sidewalls of the dummy gate strip. The dummy gate strip and the first dielectric layer underneath are removed until sidewalls of the spacers, a portion of the semiconductor fin and portions of the insulators are exposed. A second dielectric layer is selectively formed to cover the exposed portion of the semiconductor fin, wherein a thickness of the first dielectric layer is smaller than a thickness of the second dielectric layer. A gate is formed between the spacers to cover the second dielectric layer, the sidewalls of the spacers and the exposed portions of the insulators.

A semiconductor device according to the present disclosure includes a stack of first channel members, a stack of second channel members disposed directly over the stack of first channel members, a bottom source/drain feature in contact with the stack of the first channel members, a separation layer disposed over the bottom source/drain feature, a top source/drain feature in contact with the stack of second channel members and disposed over the separation layer, and a frontside contact that extends through the top source/drain feature and the separation layer to be electrically coupled to the bottom source/drain feature.

A semiconductor device includes a FinFET fin. The same FinFET fin is associated with a bottom FinFET and a top FinFET. The FinFET fin includes a lower channel portion, associated with the bottom FinFET, a top channel portion, associated with the top FinFET, and a channel isolator between the bottom channel portion and the top channel portion. A lower gate includes a vertical portion that is upon a sidewall of the bottom channel portion. An isolation layer may be formed upon the lower gate if it is desired for the top FinFET fin and the bottom FinFET fin to not share a gate. An upper gate is upon the top channel portion and is further upon the isolation layer, if present, or is upon the lower gate.

Two or more types of fin-based transistors having different gate structures and formed on a single integrated circuit are described. The gate structures for each type of transistor are distinguished at least by the thickness or composition of the gate dielectric layer(s) or the composition of the work function metal layer(s) in the gate electrode. Methods are also provided for fabricating an integrated circuit having at least two different types of fin-based transistors, where the transistor types are distinguished by the thickness and composition of the gate dielectric layer(s) and/or the thickness and composition of the work function metal in the gate electrode.