A method of forming a dielectric film having at least Si—N, Si—C, or Si—B bonds on a semiconductor substrate by atomic layer deposition (ALD), includes: supplying a precursor in a pulse to adsorb the precursor on a surface of a substrate; supplying a reactant gas in a pulse over the surface without overlapping the supply of the precursor; reacting the precursor and the reactant gas on the surface; and repeating the above steps to form a dielectric film having at least Si—N, Si—C, or Si—B bonds on the substrate. The precursor has at least one Si—C or Si—N bond, at least one hydrocarbon, and at least two halogens attached to silicon in its molecule.