Described herein are methods to form silicon dioxide films that have extremely low wet etch rate in HF solution using a thermal CVD process, ALD process or cyclic CVD process in which the silicon precursor is selected from one of:R1nR2mSi(NR3R4)4-n-m; and,a cyclic silazane of (R1R2SiNR3)p,where R1 is an alkenyl or an aromatic, such as vinyl, allyl, and phenyl; R2, R3, and R4 are selected from H, alkyl with C1-C10, linear, branched, or cyclic, an alkenyl with C2-C10 linear, branched, or cyclic, and aromatic; n=1-3, m=0-2; p=3-4.