A method includes forming a semiconductor fin over a substrate; forming a gate structure over the semiconductor fin; forming a helmet layer lining the gate structure and the semiconductor fin; etching the helmet layer to remove portions of the helmet layer from opposite sidewalls of the gate structure, wherein the remaining helmet layer comprises a first remaining portion on a top surface of the gate structure and a second remaining portion on a top surface of the semiconductor fin; forming a spacer layer covering the gate structure, wherein the spacer layer is in contact with the first remaining portion and the second remaining portion of the remaining helmet layer; etching the spacer layer and the remaining helmet layer to form gate spacers, wherein each of the gate spacers has a stepped sidewall; and forming source/drain epitaxy structures on opposite sides of the gate structure.

A method for forming nanowire semiconductor devices includes a) providing a substrate including an oxide layer defining vias; and b) depositing nanowires in the vias. The nanowires are made of a material selected from a group consisting of germanium or silicon germanium. The method further includes c) selectively etching back the oxide layer relative to the nanowires to expose upper portions of the nanowires; and d) doping the exposed upper portions of the nanowires using a dopant species.

A semiconductor device includes a substrate, a first semiconductor layer formed over the substrate, a second semiconductor layer formed over the first semiconductor layer, a third semiconductor layer formed over the second semiconductor layer, and a gate electrode, a source electrode, and a drain electrode that are formed over the third semiconductor layer. The first semiconductor layer includes a first nitride semiconductor. The second semiconductor includes a second nitride semiconductor. The third semiconductor layer includes a third nitride semiconductor. The concentration of oxygen included in the second semiconductor layer is less than 5.0×10.sup.18 cm.sup.−3. The concentration of oxygen included in the third semiconductor layer is greater than or equal to 5.0×10.sup.18 cm.sup.−3.

Devices and methods of forming a device are disclosed. The method includes providing a substrate with a cell region. Selector units and storage units are formed within the substrate. The selector unit includes first and second bipolar junction transistors (BJTs). The selector unit includes first and second bipolar junction transistors (BJTs). A BJT includes first, second and third BJT terminals. The second BJT terminals of the first and second BJTs are coupled to or serve as a common wordline terminal. The third BJT terminal of the first BJT serves as a first bitline terminal, and the third BJT terminal of the second BJT serves as a second bitline terminal. A storage unit is disposed over the selector unit. The storage unit includes a first pinning layer which is coupled to the first BJT terminal of the first BJT, a second pinning layer which is coupled to the first BJT terminal of the second BJT, a free layer which includes an elongated member with first and second major surfaces and first and second end regions separated by a free region. The first pinning layer is coupled to the second major surface of the free layer in the first end region and the second pinning layer is coupled to the second major surface of the free layer in the second end region. A reference stack is disposed on the first major surface of the free layer in the free region. The reference stack serves as a read bitline terminal.

A method of forming a semiconductor device that includes providing a vertically orientated channel region; and converting a portion of an exposed source/drain contact surface of the vertically orientated channel region into an amorphous crystalline structure. The amorphous crystalline structure is from the vertically orientated channel region. An in-situ doped extension region is epitaxially formed on an exposed surface of the vertically orientated channel region. A source/drain region is epitaxially formed on the in-situ doped extension region.

Methods for depositing a metal film on a doped amorphous silicon layer as a nucleation layer and/or a glue layer on a substrate. Some embodiments further comprise the incorporation of a glue layer to increase the ability of the doped amorphous silicon layer and metal layer to stick to the substrate.

Methods of controlling island size and density on an OMVPE growth film may comprise adding a surfactant at a critical concentration level, allowing a growth phase for a first period of time, and ending the growth phase when desired island size and density are achieved. For example, the island size and density of an OMVPE grown InGaN thin film may be controlled by adding an antimony surfactant at a critical concentration level.

A thin film transistor is used to solve a problem of low process efficiency of the conventional thin film transistor in preventing hydrogen diffusion. The thin film transistor includes a substrate, multilayer thin films laminated on the substrate, and at least one fluorine-containing thin film laminated in substitution for the multilayer thin films. Each of the multilayer thin films is a gate insulating layer, an active layer, a buffer layer, and a dielectric layer or a protective layer. Each of the at least one fluorine-containing thin film is a fluorine-doped insulating layer, a fluorine-doped active layer, a fluorine-doped buffer layer, and a fluorine-doped dielectric layer or a fluorine-doped protective layer. The invention further discloses a method for manufacturing the thin film transistor.

A method of producing graphene or other two-dimensional material such as graphene including heating the substrate held within a reaction chamber to a temperature that is within a decomposition range of a precursor, and that allows two-dimensional crystalline material formation from a species released from the decomposed precursor; establishing a steep temperature gradient (preferably >1000° C. per meter) that extends away from the substrate surface towards an inlet for the precursor; and introducing precursor through the relatively cool inlet and across the temperature gradient towards the substrate surface. The steep temperature gradient ensures that the precursor remains substantially cool until it is proximate the substrate surface thus minimizing decomposition or other reaction of the precursor before it is proximate the substrate surface. The separation between the precursor inlet and the substrate is less than 100 mm.

Trenches are formed in a semiconductor layer of a semiconductor substrate. A mixture that contains trichlorosilane and hydrogen gas is fed into a process chamber containing the semiconductor substrate. A barometric pressure in the process chamber is at least 50% of standard atmosphere. The trenches are filled with epitaxially deposited crystalline silicon.