An example embodiment is a method for filling a via hole with phase change material. The method steps include forming a bottom electrode in a substrate, depositing a dielectric layer above the bottom electrode, and forming a via hole within the dielectric layer down to a top surface of the bottom electrode. The substrate is heated to a reaction temperature and a first phase change material precursor is deposited within the via hole. The first precursor is configured to decompose on the top surface of the bottom electrode and chemisorb on a top surface of the dielectric layer at the reaction temperature. A second precursor is deposited within the via hole after the first precursor at least partially decomposes on the top surface of the bottom electrode.