Semiconductor devices and methods of manufacturing thereof

A method for fabricating semiconductor devices, comprising:

• introducing a precursor to a chamber;
• decomposing the precursor with a first plasma configured at a first power level;
• depositing a first layer on a surface of a semiconductor device based on the decomposed precursor;
• densifying the first layer with a second plasma configured at a second power level greater than the first power level;
• and
• repeating the deposition of the first layer on the surface of the semiconductor device based on the decomposed precursor and densifying the first layer with the second plasma configured at the second power level greater than the first power level to form a first gate spacer on the surface of the semiconductor device.

A semiconductor device, comprising:

• a metal gate;
• a first dielectric layer extending along a sidewall of the metal gate and comprising at least one of:
• a plurality of cross-linked first silicon-oxygen-silicon backbones;
• a plurality of cross-linked first silicon-nitrogen-silicon backbones;
• or
• a plurality of cross-linked first silicon-carbon-silicon backbones;
• and
• a second dielectric layer extending along the first dielectric layer and comprising at least one of:
• a plurality of cross-linked second silicon-oxygen-silicon backbones;
• or
• a plurality of cross-linked second silicon-carbon-silicon backbones.