Methods for tuning effective work functions of gate electrodes in semiconductor devices and semiconductor devices formed by the same are disclosed. In an embodiment, a semiconductor device includes a channel region over a semiconductor substrate; a gate dielectric layer over the channel region; and a gate electrode over the gate dielectric layer, the gate electrode including a first work function metal layer over the gate dielectric layer, the first work function metal layer including aluminum (Al); a first work function tuning layer over the first work function metal layer, the first work function tuning layer including aluminum tungsten (AlW); and a fill material over the first work function tuning layer.

A field effect transistor (FET) structure includes a substrate, an internal gate, an insulation layer, a semiconductor strip, a gate dielectric insulator, and a gate conductor. The internal gate includes a floor portion located on the substrate and a wall portion extending from the floor portion. The insulation layer is located on the floor portion of the internal gate. The semiconductor strip is located on the wall portion and a portion of the insulation layer, and the semiconductor strip includes source/drain regions and a channel region adjacent to the source/drain regions. The gate dielectric insulator is located on the channel region. The gate conductor is located on the gate dielectric insulator.

A semiconductor device is provided and includes a semiconductor fin protruding from a semiconductor substrate. The semiconductor fin includes plural pairs of semiconductor layers on the semiconductor substrate, each pair of semiconductor layers consists of a first semiconductor layer of a first conductivity type, and a second semiconductor layer of a second conductivity type. The second semiconductor layer is stacked on and contacts the first semiconductor layer.

A semiconductor device includes a semiconductor substrate, an element isolation film, and a fin having side surfaces facing each other in a first direction of an upper surface and a main surface connecting the facing side surfaces and extending in a second direction orthogonal to the first direction. The device further includes a control gate electrode arranged over the side surface via a gate insulation film and extending in the first direction, and a memory gate electrode arranged over the side surface via another gate insulation film having a charge accumulation layer and extending in the first direction. Furthermore, an overlap length by which the memory gate electrode overlaps with the side surface is smaller than an overlap length by which the control gate electrode overlaps with the side surface in the direction orthogonal to the upper surface.

A method includes providing a substrate having a mesa, forming a first opening in the mesa, the first opening being surrounded by first inner sidewalls of the mesa exposed by the first opening. The method further includes etching from a first one of the first inner sidewalls of the mesa to form a first vertical recess, the first vertical recess having a wide end and a narrow end, with the narrow end defining a first vertically recessed channel region, and forming a first gate structure over the first vertically recessed channel region.

A semiconductor device includes a semiconductor substrate, an element isolation film, and a fin having side surfaces facing each other in a first direction of an upper surface and a main surface connecting the facing side surfaces and extending in a second direction orthogonal to the first direction. The device further includes a control gate electrode arranged over the side surface via a gate insulation film and extending in the first direction, and a memory gate electrode arranged over the side surface via another gate insulation film having a charge accumulation layer and extending in the first direction. Furthermore, an overlap length by which the memory gate electrode overlaps with the side surface is smaller than an overlap length by which the control gate electrode overlaps with the side surface in the direction orthogonal to the upper surface.

One embodiment provides a method comprising etching a fin of a fin-shaped field effect transistor (FinFET) to form a reduced fin, and laterally etching the reduced fin to form a fin channel including a first fin channel sidewall and a second fin channel sidewall opposing the first fin channel sidewall. The method further comprises forming a first thin dielectric tunnel and a second thin dielectric tunnel on the first fin channel sidewall and the second fin channel sidewall, respectively. Each thin dielectric tunnel prevents lateral epitaxial crystal growth on the fin channel. The method further comprises etching an insulator layer disposed between the fin channel and a substrate of the FinFET to expose portions of a substrate surface of the substrate. A source epitaxy and a drain epitaxy are formed from vertical epitaxial crystal growth on the exposed portions of the substrate surface after epitaxial deposition.

A method for forming a semiconductor device structure is provided that includes forming an oxide layer over a substrate and forming a semiconductor layer over the oxide layer. The method includes patterning the semiconductor layer to form a fin structure over the oxide layer and removing a portion of the fin structure to form a U-shaped trench in the fin structure. The method also includes forming a gate structure on the U-shaped trench.

A method includes providing a substrate having a mesa, forming a first opening in the mesa, the first opening being surrounded by first inner sidewalls of the mesa exposed by the first opening. The method further includes etching from a first one of the first inner sidewalls of the mesa to form a first vertical recess, the first vertical recess having a wide end and a narrow end, with the narrow end defining a first vertically recessed channel region, and forming a first gate structure over the first vertically recessed channel region.

The present invention provides a field-effect transistor having an accumulation-layer-operation type field-effect transistor that includes a semiconductor layer in which a source region, a channel region, and a drain region that have either an N-type or P-type conductivity in common are formed, and a gate electrode disposed adjacent to the channel region via a gate insulating film, wherein the gate insulating film is made of a dielectric having a change gradient of a relative dielectric constant in which the relative dielectric constant changes to decrease according to the magnitude of a gate voltage applied to the gate electrode.