A transistor comprises a substrate, a pair of spacers on the substrate, a gate dielectric layer on the substrate and between the pair of spacers, a gate electrode layer on the gate dielectric layer and between the pair of spacers, an insulating cap layer on the gate electrode layer and between the pair of spacers, and a pair of diffusion regions adjacent to the pair of spacers. The insulating cap layer forms an etch stop structure that is self aligned to the gate and prevents the contact etch from exposing the gate electrode, thereby preventing a short between the gate and contact. The insulator-cap layer enables self-aligned contacts, allowing initial patterning of wider contacts that are more robust to patterning limitations.

A method of manufacturing a semiconductor device includes: forming a trench in a semiconductor layer of first conductivity type; in the trench, forming a first layer containing silicon and then forming a second layer containing first oxide or nitride on the first layer or forming the second layer and then forming the first layer on the second layer; and thermally oxidizing the first layer.

Semiconductor devices include vertically stacked channel layers formed from a semiconductor material. A metallic interface layer is formed between metal source/drain regions and the vertically stacked channel layers. The metallic interface layer includes the semiconductor material and a metal. A gate stack is formed between and around the channel layers.

A method forming a gate dielectric over a substrate, and forming a metal gate structure over the semiconductor substrate and the gate dielectric. The metal gate structure includes a first metal material. The method further includes forming a seal on sidewalls of the metal gate structure. The method further includes forming a dielectric film on the metal gate structure, the dielectric film including a first metal oxynitride comprising the first metal material and directly on the metal gate structure without extending over the seal formed on sidewalls of the metal gate structure.

Embodiments of the present disclosure provide wet process based methods for modifying threshold value (Vt) of high-k metal gate using self-assembled monolayer (SAM) on dedicated transistor. In one embodiment, the method includes forming a gate structure over a substrate, the gate structure comprising a gate dielectric layer, a barrier layer formed over the gate dielectric layer, and an oxide layer formed over the barrier layer, and forming a self-assembled monolayer on the oxide layer by exposing the oxide layer to an aqueous solution containing metal oxides in a metal dissolving acid.

A trench is formed in a semiconductor substrate. A first silicon oxide film is formed in an inside of the trench. A poly-crystalline silicon film is formed on the first silicon oxide film. A second silicon oxide film is formed from the poly-crystalline silicon film by performing a thermal oxidation treatment to the poly-crystalline silicon film. Thus, an insulating film including the first silicon oxide film and the second silicon oxide film is formed. A first conductive film is formed so as to embed the inside of the trench via the insulating film.

A method of forming a high-? dielectric cap layer on a semiconductor structure formed on a substrate includes depositing the high-? dielectric cap layer on the semiconductor structure, depositing a sacrificial silicon cap layer on the high-? dielectric cap layer, performing a post cap anneal process to harden and densify the as-deposited high-? dielectric cap layer, and removing the sacrificial silicon cap layer.

A method of forming a high-? dielectric cap layer on a semiconductor structure formed on a substrate includes depositing the high-? dielectric cap layer on the semiconductor structure, depositing a sacrificial silicon cap layer on the high-? dielectric cap layer, performing a post cap anneal process to harden and densify the as-deposited high-? dielectric cap layer, and removing the sacrificial silicon cap layer.

The present disclosure provides semiconductor devices and fabrication methods thereof. A work function layer is formed on the semiconductor substrate. A buffer layer is formed on the work function layer. The work function layer is doped through the buffer layer with impurity ions. The buffer layer obstructs a flow of the impurity ions to control a concentration of the impurity ions in different regions of the work function layer to regulate a work function of the work function layer in the different regions.

A method for fabricating semiconductor device includes the steps of: forming a shallow trench isolation (STI) in the substrate; removing part of the STI to form a trench in a substrate; forming an amorphous silicon layer in the trench and on the STI; performing an oxidation process to transform the amorphous silicon layer into a silicon dioxide layer; and forming a barrier layer and a conductive layer in the trench.