A method includes forming a semiconductor fin over a substrate; forming a gate structure over the semiconductor fin, the gate structure comprising: a first metallic layer; a second metallic layer over the first metallic layer, wherein the first metallic layer is a metal compound of a first element and a second element and the second metallic layer is a single-element metal of the second element; and an oxide layer between the first metallic layer and the second metallic layer.

A continuous or cyclic etching method for etching a metal carbide over a metal nitride is disclosed. The etching method includes the following steps: supplying plasma that is generated from a gas mixture that contains N.sub.2 and H.sub.2 and does not contain halogen gases including fluorine, chlorine, bromine, and iodine to a surface of metal carbide on at least a part of the surface, to modify the surface of metal carbide, and removing the modified surface on metal carbide by ion irradiation or by heating.

A semiconductor device according to an embodiment includes an oxide semiconductor layer provided above an insulating surface, a gate insulating layer provided above the oxide semiconductor layer, and a gate electrode provided above the oxide semiconductor layer via the gate insulating layer, wherein the gate electrode has a titanium-containing layer and a conductive layer in order from the gate insulating layer side, the gate insulating layer includes a first region overlapping the gate electrode and a second region not overlapping the gate electrode, and a thickness of the titanium-containing layer is 50% or less than a thickness of the gate insulating layer in the first region.

A semiconductor device includes first-type-channel field effect transistors (FETs) including a first first-type-channel FET including a first gate structure and a second first-type-channel FET including a second gate structure. The first first-type-channel FET has a smaller threshold voltage than the second first-type-channel FET. The first gate structure includes a first work function adjustment material (WFM) layer and the second gate structure includes a second WFM layer. At least one of thickness and material of the first and second WFM layers is different from each other.

Methods for forming a semiconductor device structure are provided. The methods may include forming a molybdenum nitride film on a substrate by atomic layer deposition by contacting the substrate with a first vapor phase reactant comprising a molybdenum halide precursor, contacting the substrate with a second vapor phase reactant comprise a nitrogen precursor, and contacting the substrate with a third vapor phase reactant comprising a reducing precursor. The methods provided may also include forming a gate electrode structure comprising the molybdenum nitride film, the gate electrode structure having an effective work function greater than approximately 5.0 eV. Semiconductor device structures including molybdenum nitride films are also provided.

A semiconductor device includes a first gate structure that includes a first interfacial layer, a first gate dielectric layer disposed over the first interfacial layer, and a first gate electrode disposed over the first gate dielectric layer. The semiconductor device also includes a second gate structure that includes a second interfacial layer, a second gate dielectric layer disposed over the second interfacial layer, and a second gate electrode disposed over the second gate dielectric layer. The first interfacial layer contains a different amount of a dipole material than the second interfacial layer.

A semiconductor device according to an embodiment includes an oxide film containing first element and a conductive film provided to be in contact with the oxide film, containing metal element and oxygen element, and having conductivity. A range of a volume density of the oxygen element in the conductive film is different between cases where the metal element are tungsten (W), molybdenum (Mo), titanium (Ti), chromium (Cr), vanadium (V), iron (Fe), copper (Cu), tantalum (Ta), or niobium (Nb).

A semiconductor device includes a first channel region disposed over a substrate, and a first gate structure disposed over the first channel region. The first gate structure includes a gate dielectric layer disposed over the channel region, a lower conductive gate layer disposed over the gate dielectric layer, a ferroelectric material layer disposed over the lower conductive gate layer, and an upper conductive gate layer disposed over the ferroelectric material layer. The ferroelectric material layer is in direct contact with the gate dielectric layer and the lower gate conductive layer, and has a U-shape cross section.

Aspects of the disclosure provide a method for forming a fin field effect transistor (FinFET) incorporating a fin top hardmask on top of a channel region of a fin. Because of the presence of the fin top hardmask, a gate height of the FinFET can be reduced without affecting proper operations of vertical gate channels on sidewalls of the fin. Consequently, parasitic capacitance between a gate stack and source/drain contacts of the FinFET can be reduced by lowering the gate height of the FinFET.

A FinFET device and a method of forming the same are provided. The method includes forming semiconductor strips over a substrate. Isolation regions are formed over the substrate and between adjacent semiconductor strips. A first recess process is performed on the isolation regions to expose first portions of the semiconductor strips. The first portions of the semiconductor strips are reshaped to form reshaped first portions of the semiconductor strips. A second recess process is performed on the isolation regions to expose second portions of the semiconductor strips below the reshaped first portions of the semiconductor strips. The second portions of the semiconductor strips are reshaped to form reshaped second portions of the semiconductor strips. The reshaped first portions of the semiconductor strips and the reshaped second portions of the semiconductor strips form fins. The fins extend away from topmost surfaces of the isolation regions.