A transistor structure includes a channel region including first sidewall. A gate electrode includes a first layer having a first portion adjacent to the first sidewall and a second portion adjacent to a gate electrode boundary sidewall. The gate electrode includes a second layer between the first and second portions of the first layer. The first layer has a first composition associated with a first work function material, and has a first lateral thickness from the first sidewall. The second layer has a second composition associated with a second work function material. Depending one a second lateral thickness of the second layer, the second layer may modulate a threshold voltage (V.sub.T) of the transistor structure by more or less. In some embodiments, a ratio of the second lateral thickness to the first lateral thickness is less than three.

A method for forming a semiconductor device includes forming a metal gate stack having a gate dielectric layer and a gate electrode disposed over the gate dielectric layer. The gate electrode includes a first metal layer and a second metal layer. The method further includes performing a plasma treatment to a top surface of the metal gate stack and forming a conductive layer over the treated top surface of the metal gate stack. A top portion of the conductive layer is formed above a top surface of the gate dielectric layer, and a bottom portion of the conductive layer penetrates into the first and the second metal layers of the gate electrode at different distances.

A device includes a substrate, first and second gate structures, first and second hybrid fins, and first and second sidewalls. The first gate structure is over and surrounds a first vertical stack of nanostructures. The second gate structure is over and surrounds a second vertical stack of nanostructures. The second gate structure and the first gate structure extend along a first direction, and are laterally separated from each other in a second direction, the second direction being substantially perpendicular to the first direction. The first hybrid fin extends through and under the first gate structure and the second gate structure, the extending being along the second direction. The second hybrid fin is between the first gate structure and the second gate structure. The second hybrid fin has: a first sidewall that abuts the first gate structure; and a second sidewall that abuts the second gate structure.

A gate dielectric structure is formed over a channel structure. One or more work function (WF) metal layers of a metal gate are formed over the gate dielectric structure. The one or more WF metal layers are treated with a fluorine-containing material. One or more processes are performed to cause fluorine from the fluorine-containing material to diffuse at least partially into the gate dielectric structure.

A device includes a first channel layer, a second channel layer, a gate structure, a source/drain epitaxial structure, and a source/drain contact. The first channel layer and the second channel layer are arranged above the first channel layer in a spaced apart manner over a substrate. The gate structure surrounds the first and second channel layers. The source/drain epitaxial structure is connected to the first and second channel layers. The source/drain contact is connected to the source/drain epitaxial structure. The second channel layer is closer to the source/drain contact than the first channel layer is to the source/drain contact, and the first channel layer is thicker than the second channel layer.

A wafer having a first region and a second region is provided. A first topography variation exists between the first region and the second region. A first layer is formed over the first region and over the second region of the wafer. The first layer is patterned. A patterned first layer causes a second topography variation to exist between the first region and the second region. The second topography variation is smoother than the first topography variation. A second layer is formed over the first region and the second region. At least a portion of the second layer is formed over the patterned first layer.

A semiconductor device includes a substrate with first and second areas, a first trench in the first area, and first and second PMOS transistors in the first area and the second area, respectively. The first transistor includes a first gate insulating layer, a first TiN layer on and contacting the first gate insulating layer, and a first gate electrode on and contacting the first TiN layer. The second transistor includes a second gate insulating layer, a second TiN layer on and contacting the second gate insulating layer, and a first TiAlC layer on and contacting the second TiN layer. The first gate insulating layer, the first TiN layer, and the first gate electrode are within the first trench. The first gate electrode does not include aluminum. A threshold voltage of the first transistor is smaller than a threshold voltage of the second transistor.

In a method of manufacturing a semiconductor device, first and second gate structures are formed. The first (second) gate structure includes a first (second) gate electrode layer and first (second) sidewall spacers disposed on both side faces of the first (second) gate electrode layer. The first and second gate electrode layers are recessed and the first and second sidewall spacers are recessed, thereby forming a first space and a second space over the recessed first and second gate electrode layers and first and second sidewall spacers, respectively. First and second protective layers are formed in the first and second spaces, respectively. First and second etch-stop layers are formed on the first and second protective layers, respectively. A first depth of the first space above the first sidewall spacers is different from a second depth of the first space above the first gate electrode layer.

A device includes a pair of gate spacers on a substrate, and a gate structure on the substrate and between the gate spacers. The gate structure includes an interfacial layer, a metal oxide layer, a nitride-containing layer, a tungsten-containing layer, and a metal compound layer. The interfacial layer is over the substrate. The metal oxide layer is over the interfacial layer. The nitride-containing layer is over the metal oxide layer. The tungsten-containing layer is over the nitride-containing layer. The metal compound layer is over the tungsten-containing layer. The metal compound layer has a different material than a material of the tungsten-containing layer.

The present disclosure provides a method of manufacturing a semiconductor device. The method includes steps of providing a patterned mask having a plurality of openings on a substrate; etching the substrate through the openings to form an etched substrate and a trench in the etched substrate, wherein the etched substrate comprises a protrusion; introducing dopants having a first conductivity type in the etched substrate and on either side of the trench to form a plurality of first impurity regions; forming an isolation film in the trench; and depositing a conductive material on the isolation film.