A method for forming a semiconductor structure includes the following steps. A semiconductor device is formed over a substrate. A trench is formed in the semiconductor device. The trench is filled with a gap-fill material using a deposition process, wherein a precursor used in the deposition process includes azidosilane, di-azidosilane or halide azidosilane.

A method includes forming first, second, third, fourth, fifth, and sixth channel patterns on a semiconductor substrate; forming a first isolation wall interposing the first and second channel patterns, a second isolation wall interposing the third and fourth channel patterns, wherein the first isolation wall further continuously extends to interpose the fifth and sixth channel patterns; forming a first gate pattern extending across the first, second, third, and fourth channel patterns and the first and second isolation walls, and a second gate pattern extending across the fifth and sixth channel patterns and the first isolation wall from the top view, wherein the first, second, third, fourth, and sixth channel patterns respectively have first, second, third, fourth, and sixth dimensions in a lengthwise direction of the first gate pattern, and the sixth dimension is greater than the first, second, third, and fourth dimensions.

A high voltage transistor may include a plurality of source/drain regions, a gate structure, and a gate oxide layer that enables the gate structure to selectively control a channel region between the source/drain regions. The gate oxide layer may extend laterally outward toward one or more of the plurality of source/drain regions such that at least a portion of the gate oxide layer is not under the gate structure. The gate oxide layer extending laterally outward from under the gate structure enables the gate oxide layer to be used as a self-aligned structure for forming the source/drain regions of the high voltage transistor. In particular, the gate oxide layer extending laterally outward from under the gate structure enables the gate oxide layer to be used to form the source/drain regions at a greater spacing from the gate structure without the use of additional implant masks when forming the source/drain regions.

An exemplary device includes a frontside power rail disposed over a frontside of a substrate, a backside power rail disposed over a backside of the substrate, an epitaxial source/drain structure disposed between the frontside power rail and the backside power rail. The epitaxial source/drain structure is connected to the frontside power rail by a frontside source/drain contact. The epitaxial source/drain structure is connected to the backside power rail by a backside source/drain via. The backside source/drain via is disposed in a substrate, and a dielectric layer is disposed between the substrate and the backside power rail. The backside source/drain via extends through the dielectric layer and the substrate. A frontside silicide layer may be between the frontside source/drain contact and the epitaxial source/drain structure, and a backside silicide layer may be between the backside source/drain contact and the epitaxial source/drain structure, such that the epitaxial source/drain structure between silicide layers.

A transistor and a manufacturing method. The transistor includes a semiconductor base substrate, an active structure, a dielectric structure, and a gate stack structure. The active structure is formed on the semiconductor base substrate. The active structure includes a source region, a drain region, and a channel region located between the source region and the drain region. The channel region includes at least two nanostructures stacked in a thickness direction of the semiconductor base substrate. In the channel region, a bottom nanostructure has a greater width than other nanostructures. The dielectric structure is formed between the semiconductor base substrate and the active structure. The dielectric structure is in contact with the bottom nanostructure. The gate stack structure is formed on a surface of the bottom nanostructure not in contact with the dielectric structure, and the gate stack surrounds a periphery of the other nanostructures.

Techniques are disclosed herein for creating metal bitlines (BLs) in stacked wafer memory. Using techniques described herein, metal BLs are created on a bottom surface of a wafer. The metal BLs can be created using different processes. In some configurations, a salicide process is utilized. In other configurations, a damascene process is utilized. Using metal reduces the resistance of the BLs as compared to using non-metal diffused BLs. In some configurations, wafers are stacked and bonded together to form three-dimensional memory structures.

A method includes providing a semiconductor structure having a metal gate structure (MG), gate spacers disposed on sidewalls of the MG, and a source/drain (S/D) feature disposed adjacent to the gate spacers; forming a first metal layer over the S/D feature and between the gate spacers; recessing the first metal layer to form a trench; forming a dielectric layer on sidewalls of the trench; forming a second metal layer over the first metal layer in the trench, wherein sidewalls of the second metal layer are defined by the dielectric layer; and forming a contact feature over the MG to contact the MG.

Semiconductor devices and method of forming the same are provided. In one embodiment, a semiconductor device includes a first transistor and a second transistor. The first transistor includes two first source/drain features and a first number of nanostructures that are stacked vertically one over another and extend lengthwise between the two first source/drain features. The second transistor includes two second source/drain features and a second number of nanostructures that are stacked vertically one over another and extend lengthwise between the two second source/drain features.

A method for fabricating a semiconductor device includes the steps of first forming a gate dielectric layer on a substrate, forming a gate material layer on the gate dielectric layer, patterning the gate material layer and the gate dielectric layer to form a gate structure, removing a portion of the gate dielectric layer, forming a spacer adjacent to the gate structure and at the same time forming an air gap between the gate dielectric layer and the spacer, and then forming a source/drain region adjacent to two sides of the spacer.

A method for fabricating a semiconductor device includes the steps of first forming a gate dielectric layer on a substrate, forming a gate material layer on the gate dielectric layer, patterning the gate material layer and the gate dielectric layer to form a gate structure, removing a portion of the gate dielectric layer, forming a spacer adjacent to the gate structure and at the same time forming an air gap between the gate dielectric layer and the spacer, and then forming a source/drain region adjacent to two sides of the spacer.