A method for depositing a dielectric film in a trench by plasma-enhanced atomic layer deposition (PEALD) includes depositing a dielectric film in a trench of a substrate by PEALD under conditions wherein the wet etch rate of the depositing film on a top surface of the substrate is substantially equivalent to or higher than the wet etch rate of the depositing film at a sidewall of the trench, wherein a precursor fed into the reaction space has —N(CH3)2 as a functional group.