Forming high carbon content flowable dielectric film with low processing damage

A method of fabricating a dielectric film, the method comprising:

• depositing a first precursor on a substrate, the first precursor comprising a cyclic carbosiloxane group comprising a six-membered ring of three silicon atoms alternating with three oxygen atoms and having a carbon to silicon ratio (C:Si) greater than 2:1;
• depositing a second precursor on the substrate, the first precursor and the second precursor forming a preliminary film, and the second precursor comprising silicon, carbon, and hydrogen;
• exposing the preliminary film to ammonia to form a nitrogen-treated preliminary film;
• and
• curing, subsequent to exposing the preliminary film to ammonia, the nitrogen-treated preliminary film to form a porous dielectric film.