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.

Embodiments relate to a semiconductor structure and a fabrication method thereof. The semiconductor structure includes: a semiconductor substrate; a dielectric layer positioned on the semiconductor substrate; and a gate structure, including a bandgap-tunable material layer. The bandgap-tunable material layer is positioned on the dielectric layer, a Fermi level of the bandgap-tunable material layer shifts to a conduction band when electrons inflow, and the Fermi level of the bandgap-tunable material layer shifts to a valence band when the electrons outflow. The semiconductor structure and the fabrication method thereof can effectively reduce fabrication difficulty of the gate structure.

In some embodiments, the present disclosure relates to a semiconductor device comprising a source and drain region arranged within a substrate. A conductive gate is disposed over a doped region of the substrate. A gate dielectric layer is disposed between the source region and the drain region and separates the conductive gate from the doped region. A bottommost surface of the gate dielectric layer is below a topmost surface of the substrate. First and second sidewall spacers are arranged along first and second sides of the conductive gate, respectively. An inner portion of the first sidewall spacer and an inner portion of the second sidewall spacer respectively cover a first and second top surface of the gate dielectric layer. A drain extension region and a source extension region respectively separate the drain region and the source region from the gate dielectric layer.

Embodiments provide a semiconductor structure and a method for fabricating a semiconductor structure. The semiconductor structure includes: a source region and a drain region arranged at intervals on a substrate; a gate oxide layer arranged between the source region and the drain region; a gate structure arranged on the gate oxide layer; and a conductive plug arranged at a corresponding position of the source region and a corresponding position of the drain region. The gate structure includes a conductive layer having an inclined side surface facing toward the conductive plug. Compared with a traditional gate structure, in the solutions of the present disclosure, a distance between the conductive layer having the inclined side surface and the conductive plug is increased, thereby reducing a parasitic capacitance between the gate structure and the conductive plug, such that capacitance between a gate and the source/drain region is reduced, and device characteristics are improved.

The invention provides a method for forming a semiconductor structure. The method includes providing a substrate, forming a gate structure on the substrate, respectively forming an epitaxial layer on both sides of the gate structure, and performing a pre-amorphization doping step on the substrate. After the pre-amorphization doping step, a defect is generated in the epitaxial layer, an outer spacer is formed beside the gate structure, and a chemical cleaning step is performed to remove a part of the epitaxial layer, and the defect in the epitaxial layer is removed.

In one exemplary aspect, a method for semiconductor manufacturing comprises forming first and second silicon nitride features on sidewall surfaces of a contact hole, where the contact hole is disposed in a dielectric layer and above a source/drain (S/D) feature. The method further comprises forming a contact plug in the contact hole, the contact plug being electrically coupled to the S/D feature, removing a top portion of the contact plug to create a recess in the contact hole, forming a hard mask layer in the recess, and removing the first and second silicon nitride features via selective etching to form first and second air gaps, respectively.

A semiconductor device includes an active gate metal structure disposed over a substrate, the active gate metal structure having a first sidewall and a second sidewall opposite to each other. The semiconductor device includes a first source/drain region disposed adjacent the first sidewall of the active gate metal structure with a first lateral distance. The semiconductor device includes a second source/drain region disposed adjacent the second sidewall of the active gate metal structure with a second lateral distance, wherein the second lateral distance is substantially greater than the first lateral distance. The semiconductor device includes a resist protective oxide (RPO) comprising a first portion extending over a portion of a major surface of the substrate that is laterally located between the second sidewall and the second source/drain region, wherein the RPO has no portion extending over a top surface of the active gate metal structure.

A method includes: forming a gate over a semiconductor substrate; forming doped regions in the semiconductor substrate; depositing a dielectric layer on sidewalls of the gate, the dielectric layer including vertical portions laterally surrounding a sidewall of the gate; depositing a spacer laterally surrounding the dielectric layer, the spacer including a carbon-free portion laterally surrounding the vertical portions of the dielectric layer and a carbon-containing portion laterally surrounding the carbon-free portion; forming source/drain regions in the semiconductor substrate; performing an etching operation to remove the gate and vertical portions of the dielectric layer using the carbon-free portion as an etching stop layer to thereby expose the carbon-free portion and form a recess; and forming a gate dielectric layer and a conductive layer in the recess, wherein the gate dielectric layer extends in at least a portion of an area where the vertical portions of the dielectric layer are etched.

A manufacturing method of a semiconductor device includes forming a contact opening in a wafer. The wafer includes a substrate, a gate structure over the substrate and a dielectric layer over the substrate and surrounding the gate structure, and the contact opening passes through the dielectric layer and exposes the substrate. A recess is formed in the substrate such that the recess is connected to the contact opening. An oxidation process is performed to convert a portion of the substrate exposed in the recess to form a protection layer lining a sidewall and a bottom surface of the recess. The protection layer is etched back to remove a first portion of the protection layer in contact with the bottom surface of the recess of the substrate. A metal alloy structure is formed at the bottom surface of the recess of the substrate.

An integrated circuit device includes a plurality of metal gates each having a metal electrode and a high-κ dielectric and a plurality of polysilicon gates each having a polysilicon electrode and conventional (non high-κ) dielectrics. The polysilicon gates may have adaptations for operation as high voltage gates including thick dielectric layers and area greater than one μm.sup.2. Polysilicon gates with these adaptations may be operative with gate voltages of 10V or higher and may be used in embedded memory devices.