Quantitative Analysis of the Incorporation Behaviors of Sr and Ti Atoms During the Atomic Layer Deposition of SrTiO Thin Films.

The atomic layer deposition (ALD) of multication oxide films is complicated because the deposition behaviors of the component oxides are not independent of one another. In this study, the Ti and Sr atom incorporation behaviors during the ALD of SrTiO films were quantitatively examined via the carefully designed ALD process sequences. HO and O were adopted as the oxygen sources of the SrO subcycles, whereas only O was used for the TiO ALD subcycles. Apart from the general conjecture on the roles of the different types of oxygen sources, the oxygen source that was adopted for the subcycles of the other component oxide had almost complete control of the metal atom incorporation behaviors. This means that the first half-cycle of ALD played a dominant role in determining the metal incorporation rate, which revealed the critical role of the steric hindrance effect during the metal precursor injection for the ALD rate. O had almost doubled its reactivity toward the Ti and Sr precursors compared with HO. Although these are the expected results from the common knowledge on ALD, the quantitative analysis of the incorporation behaviors of each metal atom provided insightful viewpoints for the ALD process of this technically important oxide material. Furthermore, the SrTiO films with a bulk dielectric constant as high as 236 were obtained by the Ru-SrTiO-RuO capacitor structure.