Methods of forming conformal silicon oxycarbonitride thin films on high aspect ratio semiconductor structures

A method of manufacturing a gate-all-around device, the method comprising:

• in a first deposition cycle, exposing a substrate comprising a dummy gate structure on a top surface of a superlattice structure in a semiconductor processing chamber to a first precursor comprising a silicon- and carbon-containing precursor, a first purge gas, a second precursor comprising one or more of ammonia (NH3), a diamine (NH2—R—NH2 wherein R is an alkyl group), hydrazine (N2H4), and diazene (N2H2), and a second purge gas to deposit a conformal silicon carbonitride (SiCN) film as an inner spacer on the superlattice structure, the superlattice structure including a plurality of semiconductor material layers and a corresponding plurality of release layers alternatingly arranged in a plurality of stacked pairs;
• oxidizing the conformal silicon carbonitride (SiCN) film to form a silicon oxycarbonitride (SiOCN) film;
• and
• thermally annealing the conformal silicon oxycarbonitride (SiOCN) film to form a high-quality conformal silicon oxycarbonitride (SiOCN) film having a wet etch rate less than 10 Å/min in 100:1 dilute hydrofluoric acid (DHF).