A method of forming a semiconductor device includes depositing a target metal layer in an opening. Depositing the target metal layer comprises performing a plurality of deposition cycles. An initial deposition cycle of the plurality of deposition cycles comprises: flowing a first precursor in the opening, flowing a second precursor in the opening after flowing the first precursor, and flowing a reactant in the opening. The first precursor attaches to upper surfaces in the opening, and the second precursor attaches to remaining surfaces in the opening. The first precursor does not react with the second precursor, and the reactant reacts with the second precursor at a greater rate than the reactant reacts with the first precursor.

Semiconductor structures and methods of fabrication are provided. A method according to the present disclosure includes receiving a workpiece that includes an active region over a substrate and having first semiconductor layers interleaved by second semiconductor layers, and a dummy gate stack over a channel region of the active region, etching source/drain regions of the active region to form source/drain trenches that expose sidewalls of the active region, selectively and partially etching second semiconductor layers to form inner spacer recesses, forming inner spacer features in the inner spacer recesses, forming channel extension features on exposed sidewalls of the first semiconductor layers, forming source/drain features over the source/drain trenches, removing the dummy gate stack, selectively removing the second semiconductor layers to form nanostructures in the channel region, forming a gate structure to wrap around each of the nanostructures. The channel extension features include undoped silicon.

A method includes forming a p-type transistor. The method includes forming a gate dielectric on a semiconductor region, and depositing a p-type work-function layer on the gate dielectric. The p-type work-function layer includes a metal nitride, which includes a first metal and a second metal. An n-type work-function layer is deposited over the p-type work-function layer. A p-type source/drain region is formed aside of the semiconductor region.

In an embodiment, a device includes: a source/drain region over a semiconductor substrate; a dielectric layer over the source/drain region, the dielectric layer including a first dielectric material; an inter-layer dielectric over the dielectric layer, the inter-layer dielectric including a second dielectric material and an impurity, the second dielectric material different from the first dielectric material, a first portion of the inter-layer dielectric having a first concentration of the impurity, a second portion of the inter-layer dielectric having a second concentration of the impurity, the first concentration less than the second concentration; and a source/drain contact extending through the inter-layer dielectric and the dielectric layer to contact the source/drain region, the first portion of the inter-layer dielectric disposed between the source/drain contact and the second portion of the inter-layer dielectric.

A semiconductor structure according to the present disclosure includes a substrate, a first base fin and a second base fin arising from the substrate, an isolation structure disposed between the first base fin and the second base fin, first channel members disposed over the first base fin, second channel members disposed over the second base fin, a region isolation feature extending into the substrate, a first gate structure wrapping around each of the first channel members, second gate structure wrapping around each of the second channel members, a first gate cut feature extending through the first gate structure and into the isolation feature, and a second gate cut feature extending though the second gate structure and into the isolation feature. Each of the first gate cut feature and the second gate cut feature are spaced apart from the region isolation feature.

A method includes forming a gate stack over a semiconductor region, etching the semiconductor region to form a source/drain recess aside of the gate stack, depositing a first dielectric layer, wherein a portion of the first dielectric layer is in the source/drain recess, performing a treatment process on the first dielectric layer, depositing a second dielectric layer on the first dielectric layer, and etching the second dielectric layer and the first dielectric layer. A first portion of the first dielectric layer and a second portion of the second dielectric layer remain at a bottom of the source/drain recess to form a dielectric region. A source/drain region is deposited in the source/drain recess and over the dielectric region.

A semiconductor device may include a semiconductor substrate including first and second regions, a first gate structure on the first region, and a second gate structure on the second region. Each of the first and second gate structures may include a metal pattern, a high-k dielectric pattern between the semiconductor substrate and the metal pattern, and a work-function layer between the high-k dielectric pattern and the metal pattern. The work-function layer of the first gate structure may include a first metal element in the metal pattern of the first gate structure and a dipole material in the high-k dielectric pattern of the first gate structure, and the work-function layer and the high-k dielectric pattern in the second gate structure may include a metal oxide material. In the second gate structure, an oxygen content in the work-function layer may be higher than that in the high-k dielectric pattern.

Methods for fabricating semiconductor structures are provided. An exemplary method includes forming a first transistor structure and a second transistor structure, wherein each transistor structure includes at least one channel region; depositing a work function material over the first transistor structure and the second transistor structure; and selectively removing the work function material from the first transistor structure while maintaining the work function material over the second transistor structure using a masked etching process, wherein after the selectively removing, the first transistor structure is free of the work function material and the second transistor structure retains the work function material.

Embodiments of the present disclosure provide a semiconductor device structure having vertically stacked complementary field effect transistors (CFETs). The CFETs are formed by bonding two substrates having semiconductor stacks formed thereon. A bonding structure is formed between the semiconductor stacks using wafer bonding technology. Embodiments of the resent disclosure enable the flexibility of choosing different N/P channel properties, provide a simple way to form the N/P channel isolation structure, and reduce potential leakage path and defects in stacked CFETs.

Disclosed herein are methods, devices and systems including a substrate, a transistor channel on the substrate and extending in direction parallel to the substrate, a first electrode extending in a direction orthogonal to the substrate and coupled to the transistor channel, a second electrode coupled to the transistor channel and extending in a direction orthogonal to the substrate and parallel to the first electrode, and a first epitaxial structure arranged between the transistor channel and the first electrode. The first epitaxial structure may share a common crystalline orientation with the transistor channel, and may separate a surface of the first electrode and a surface of the transistor channel in a direction parallel to the substrate by a distance varying along the length of the first electrode.