A method of manufacturing a semiconductor device includes forming a fin structure in which first semiconductor layers and second semiconductor layers are alternatively stacked, the first and second semiconductor layers having different material compositions; forming a sacrificial gate structure over the fin structure; forming a gate spacer on sidewalls of the sacrificial gate structure; etching a source/drain (S/D) region of the fin structure, which is not covered by the sacrificial gate structure and the gate spacer, thereby forming an S/D trench; laterally etching the first semiconductor layers through the S/D trench, thereby forming recesses; selectively depositing an insulating layer on surfaces of the first and second semiconductor layers exposed in the recesses and the S/D trench, but not on sidewalls of the gate spacer; and growing an S/D epitaxial feature in the S/D trench, thereby trapping air gaps in the recesses.

A semiconductor device includes a plurality of semiconductor layers vertically separated from one another. The semiconductor device includes a gate structure that comprises a lower portion and an upper portion. The lower portion wraps around each of the plurality of semiconductor layers. The semiconductor device includes a gate spacer that extends along a sidewall of the upper portion of the gate structure and comprises a first layer and a second layer. The first layer is in contact with a first portion of the sidewall and the second layer is in contact with a second portion of the sidewall.

A method includes removing a first dummy gate stack and a second dummy gate stack to form a first trench and a second trench. The first dummy gate stack and the second dummy gate stack are in a first device region and a second device region, respectively. The method further includes depositing a first gate dielectric layer and a second gate dielectric layer extending into the first trench and the second trench, respectively, forming a fluorine-containing layer comprising a first portion over the first gate dielectric layer, and a second portion over the second gate dielectric layer, removing the second portion, performing an annealing process to diffuse fluorine in the first portion into the first gate dielectric layer, and at a time after the annealing process, forming a first work-function layer and a second work-function layer over the first gate dielectric layer and the second gate dielectric layer, respectively.

A device comprises a substrate, a semiconductor channel over the substrate, and a gate structure over and laterally surrounding the semiconductor channel. The gate structure comprises a first dielectric layer comprising a first dielectric material including dopants. A second dielectric layer is on the first dielectric layer, and comprises a second dielectric material substantially free of the dopants. A metal fill layer is over the second dielectric layer.

A semiconductor device and related method for forming a gate structure. In some embodiments, a semiconductor device includes a fin extending from a substrate. In some cases, the fin includes a plurality of semiconductor channel layers. In some examples, the semiconductor device further includes a gate dielectric surrounding each of the plurality of semiconductor channel layers. In some embodiments, a first thickness of the gate dielectric disposed on a top surface of a topmost semiconductor channel layer of the plurality of semiconductor channel layers is greater than a second thickness of the gate dielectric disposed on a surface of another semiconductor channel layer disposed beneath the topmost semiconductor channel layer.

A semiconductor device includes stacks of nano-structures that each extend in a first horizontal direction. The stacks each extend in a vertical direction and are separated from one another in a second horizontal direction. A first gate is disposed over a first subset of the stacks. A second gate is disposed over a second subset of the stacks. A first conductive capping layer is disposed over a substantial entirety of an upper surface of the first gate. A second conductive capping layer is disposed over a substantial entirety of an upper surface of the second gate. A dielectric structure is disposed between the first gate and the second gate in the second horizontal direction. The dielectric structure physically and electrically separates the first gate and the second gate. An upper surface of the dielectric structure is substantially free of having the first or second conductive capping layers disposed thereon.

Embodiments utilize an electro-chemical process to deposit a metal gate electrode in a gate opening in a gate replacement process for a nanosheet FinFET device. Accelerators and suppressors may be used to achieve a bottom-up deposition for a fill material of the metal gate electrode.

A semiconductor device with different configurations of contact structures and a method of fabricating the same are disclosed. The method includes forming first and second fin structures on a substrate, forming n- and p-type source/drain (S/D) regions on the first and second fin structures, respectively, forming first and second contact openings on the n- and p-type S/D regions, respectively, forming a carbon-based layer in the first and second contact openings, performing a remote plasma treatment with radicals on the carbon-based layer to form a remote plasma treated layer, selectively removing a portion of the remote plasma treated layer, forming a p-type work function metal (pWFM) silicide layer on the p-type S/D region, and forming an n-type work function metal (nWFM) silicide layer on the pWFM silicide layer and on the n-type S/D region.

In an example, a method includes depositing a first sidewall spacer layer over a substrate having a layer stack including alternating layers of a nanosheet and a sacrificial layer, and a dummy gate formed over the layer stack, the first sidewall spacer layer formed over the dummy gate. The method includes depositing a metal-containing liner over the first sidewall spacer layer; forming a first sidewall spacer along the dummy gate by anisotropically etching the metal-containing liner and the first sidewall spacer layer; performing an anisotropic etch back process to form a plurality of vertical recesses in the layer stack; laterally etching the layer stack and form a plurality of lateral recesses between adjacent nanosheets; depositing a second sidewall spacer layer to fill the plurality of lateral recesses; and etching a portion of the second sidewall spacer layer to expose tips of the nanosheet layers.

A semiconductor device structure includes a first S/D feature over a first device region of a substrate, a plurality of first semiconductor layers over the first device region of the substrate, and each first semiconductor layer is in contact with the first source/drain feature, a first gate electrode layer surrounding a portion of each first semiconductor layer, and a first dielectric spacer contacting the first S/D feature, the first dielectric spacer disposed between and in contact with two first semiconductor layers of the plurality of the first semiconductor layers. The substrate comprises a first dopant region underneath the first S/D feature and a second dopant region underneath first gate electrode layer and radial outwardly of the first dopant region, the first dopant region comprising first dopants having a first conductivity type and a first dopant concentration and the second dopant region comprising the first dopants having a second dopant concentration less than the first dopant concentration.