A semiconductor device that includes a gate structure on a channel region of a semiconductor device. Source and drain regions may be present on opposing sides of the channel region. The semiconductor device may further include a composite gate sidewall spacer present on a sidewall of the gate structure. The composite gate sidewall spacer may include a first composition portion having an air gap encapsulated therein, and a second composition portion that is entirely solid and present atop the first composition portion.

Solid assemblies having a composite dielectric spacer and processes for fabricating the solid assemblies are provided. The composite dielectric spacer can include, in some embodiments, a first dielectric layer and a second dielectric layer having a mutual interface. The composite dielectric spacer can separate a contact member from a conductive interconnect member, thus reducing the capacitance between such members with respect to solid assemblies that include one of first dielectric layer or the second dielectric layer. The composite dielectric spacer can permit maintaining the real estate of an interface between the conductive interconnect and a trench contact member that has an interface with a carrier-doped epitaxial layer embodying or constituting a source contact region or a drain contact region of a field effect transistor. The trench contact member can form another interface with the conductive interconnect member, providing a satisfactory contact resistance therebetween.

A doped or undoped silicon carbide film can be deposited using a remote plasma chemical vapor deposition (CVD) technique. One or more silicon-containing precursors are provided to a reaction chamber. Radical species, such as hydrogen radical species, are provided in a substantially low energy state or ground state and interact with the one or more silicon-containing precursors to deposit the silicon carbide film. A co-reactant may be flowed with the one or more silicon-containing precursors, where the co-reactant is a carbon-containing precursor and each silicon-containing precursor is a silane-based precursor with at least a silicon atom having two or more hydrogen atoms bonded to the silicon atom.

Methods and devices that provide for a fin structure and a dielectric fin structure. A gate structure is formed over the fin structure and the hybrid fin structure. A plurality of dielectric layers is adjacent the gate structure and over the hybrid fin structure between the gate structure and a contact element over the dielectric fin structure. The plurality of dielectric layers includes an air gap, formed by removal of a dummy spacer layer.

A semiconductor structure includes a stack of semiconductor layers disposed over a substrate, a metal gate stack having a top portion disposed over the stack of semiconductor layers and a bottom portion interleaved with the stack of semiconductor layers, an inner spacer disposed on sidewalls of the bottom portion of the metal gate stack, an air gap extending in the inner spacer, and an epitaxial source/drain (S/D) feature disposed over the inner spacer and adjacent to the metal gate stack.

A memory device includes a stack structure over a substrate, a channel structure extending in the stack structure, and a dielectric layer over the channel structure. The dielectric layer includes a first material. The memory device may also include a drain-select gate (DSG) cut structure extending through the dielectric layer. The DSG cut structure includes a second material different from the first material.

A thin film transistor includes a substrate, a semiconductor layer, a gate insulating layer, a gate, a source and a drain. The semiconductor layer is located above the substrate. The gate insulating layer is located above the semiconductor layer. The gate is located above the gate insulating layer and overlapping with the semiconductor layer. The gate includes a first portion, a second portion and a third portion. The first portion is extending along the surface of the gate insulating layer and directly in contact with the gate insulating layer. The second portion is separated from the gate insulating layer. Taking the surface of the gate insulating layer as a reference, the top surface of the second portion is higher than the top surface of the first portion. The third portion connects the first portion to the second portion. The source and the drain are electrically connected to the semiconductor layer.

A method includes providing a semiconductor structure including a device fin protruding from a substrate, forming a dummy gate stack over the device fin, forming a first spacer over the device fin and the dummy gate stack, forming a second spacer over the first spacer, forming a dielectric feature adjacent to the second spacer, and replacing the dummy gate stack with a metal gate stack. Thereafter, the method removes the second spacer, thereby forming an air gap between the first spacer and the dielectric feature and wrapping around the device fin. The method then forms a sealing layer over the first spacer and the dielectric feature, thereby sealing the air gap.

Gates having air gaps therein, and methods of fabrication thereof, are disclosed herein. An exemplary gate includes a gate electrode and a gate dielectric. A first air gap is between and/or separates a first sidewall of the gate electrode from the gate dielectric, and a second air gap is between and/or separates a second sidewall of the gate electrode from the gate dielectric. A dielectric cap may be disposed over the gate electrode, and the dielectric cap may wrap a top of the gate electrode. The dielectric cap may fill a top portion of the first air gap and a top portion of the second air gap. The gate may be disposed between a first epitaxial source/drain and a second epitaxial source/drain, and a width of the gate is about the same as a distance between the first epitaxial source/drain and the second epitaxial source/drain.

Provided are FinFET devices and methods of forming the same. A FinFET device includes a substrate, a metal gate strip, gate spacers and a dielectric helmet. The substrate has fins. The metal gate strip is disposed across the fins and has a reversed T-shaped portion between two adjacent fins. The gate spacers are disposed on opposing sidewalls of the metal gate strip. A dielectric helmet is disposed over the metal gate strip.