Semiconductor devices and methods of manufacturing thereof

A method for fabricating a semiconductor device, comprising:

• exposing a first conduction and second conduction channel;
• forming a dielectric layer over the first conduction channel and the second conduction channel;
• forming a blocking layer over the dielectric layer;
• performing a first annealing process to modulate the blocking layer and the dielectric layer;
• overlaying the blocking layer around the first conduction channel with a first high-k dielectric layer and the blocking layer around the second conduction channel with a second high-k dielectric layer;
• forming a threshold voltage modulation layer over the first high-k dielectric layer;
• performing a second annealing process to drive dopants from the threshold voltage modulation layer into the first high-k dielectric layer;
• and
• overlaying the first high-k dielectric layer with a third high-k dielectric layer and the second high-k dielectric layer with a fourth high-k dielectric layer, respectively.

A method for fabricating a semiconductor device, comprising:

• exposing a circumference of first and second nanostructures vertically spaced from one another;
• wrapping around the circumferences of the first and second nanostructures with first and second dielectric interfacial layers, respectively;
• wrapping around the first and second dielectric interfacial layers with first and second blocking layers, respectively;
• densifying the first and second dielectric interfacial layers through an annealing process;
• wrapping around the first and second blocking layers with first and second high-k dielectric layers, respectively;
• wrapping around the first high-k dielectric layer with a threshold voltage modulation layer;
• adjusting a doping profile of the first high-k dielectric layer through another annealing process;
• wrapping around the first and second high-k dielectric layers with third and fourth high-k dielectric layers;
• and
• wrapping around the third and fourth high-k dielectric layers with first and second work function metal layers, respectively.