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.

Semiconductor structures and methods are provided. An exemplary method according to the present disclosure includes forming a first and a second fin-shaped active region over a substrate, the first and second fin-shaped active regions extending lengthwise along a first direction, forming a gate structure over channel regions of the first and second fin-shaped active regions, the gate structure extending lengthwise along a second direction substantially perpendicular to the first direction, forming a trench to separate the gate structure into two segments, the trench extending lengthwise along the first direction and being disposed between the first and second fin-shaped active regions, performing an etching process to enlarge an upper portion of the trench, and forming a gate isolation structure in the trench, and, in a cross-sectional view cut through both the first and second fin-shaped active regions and the gate structure, the gate isolation structure is a T-shape structure.

A method for forming a semiconductor device includes: forming a gate structure over a fin, where the fin protrudes above a substrate; forming an opening in the gate structure; forming a first dielectric layer along sidewalls and a bottom of the opening, where the first dielectric layer is non-conformal, where the first dielectric layer has a first thickness proximate to an upper surface of the gate structure distal from the substrate, and has a second thickness proximate to the bottom of the opening, where the first thickness is larger than the second thickness; and forming a second dielectric layer over the first dielectric layer to fill the opening, where the first dielectric layer is formed of a first dielectric material, and the second dielectric layer is formed of a second dielectric material different from the first dielectric material.

A method of applying and then removing a protective layer over a portion of a gate stack is provided. The protective layer is deposited and then a plasma precursor is separated into components. Neutral radicals are then utilized in order to remove the protective layer. In some embodiments the removal also forms a protective by-product which helps to protect underlying layers from damage during the etching process.

A method of manufacturing a gate structure includes at least the following steps. A gate dielectric layer is formed. A work function layer is deposited on the gate dielectric layer. A barrier layer is formed on the work function layer. A metal layer is deposited on the barrier layer to introduce fluorine atoms into the barrier layer. The barrier layer is formed by at least the following steps. A first TiN layer is formed on the work function layer. A top portion of the first TiN layer is converted into a trapping layer, and the trapping layer includes silicon atoms or aluminum atoms. A second TiN layer is formed on the trapping layer.

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.

A semiconductor device a method of forming the same are provided. The method includes forming a fin extending from a substrate and forming a gate dielectric layer along a top surface and sidewalls of the fin. A first thickness of the gate dielectric layer along the top surface of the fin is greater than a second thickness of the gate dielectric layer along the sidewalls of the fin.

A semiconductor device includes a first transistor, a second transistor, a third transistor, and a fourth transistor. The first and second transistors operate under a lower gate voltage than the third and fourth transistors. The first transistor has a first active gate structure and the second transistor has a second active gate structure. The first and second active gate structures are separated by a first gate isolation structure along a first direction. The third transistor has a third active gate structure and the fourth transistor has a fourth active gate structure. The third and fourth active gate structures are separated by a second gate isolation structure along the first direction. The variation of a first distance between respective sidewalls of the first gate isolation structure is equal to the variation of a second distance between respective sidewalls of the second gate isolation structure along the first direction.

A semiconductor structure includes a first device and a second device. The first device includes a plurality of first fins, a first work function layer over the plurality of first fins, and a first contact layer over the first work function layer. The second device includes a plurality of second fins, a second work function layer and the first work function layer over the plurality of the second fins, and a second contact layer over the first work function layer and the second work function layer. A distance between a bottom surface of the first work function layer and a bottom surface of the first contact layer is greater than a distance between a side surface of the first work function layer of the first device and a side surface of the first contact layer.

A semiconductor structure, a method for manufacturing a FinFET structure and a method for manufacturing a semiconductor structure are provided. The method for forming a FinFET structure includes: providing a FinFET precursor including a plurality of fins and a plurality of gate trenches between the fins; forming a first portion of the trench dummy of a dummy gate within the plurality of gate trenches; removing at least a part of the first portion of the trench dummy; forming a second portion of the trench dummy over the first portion of the trench dummy; performing a first thermal treatment to the first and second portions of the trench dummy; and forming a blanket dummy of the dummy gate over the second portion of the trench dummy. The present disclosure further provides a FinFET structure with an improved metal gate.