Department of Materials Science and Engineering and Inter-University Semiconductor Research Center , Seoul National University , Seoul 08826 , Republic of Korea.
Department of Materials Science and Engineering , Dankook University , Cheonan , Chungnam 31118 , Republic of Korea.
ACS Appl Mater Interfaces. 2018 Mar 14;10(10):8836-8844. doi: 10.1021/acsami.7b18807. Epub 2018 Mar 5.
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.
多价氧化物薄膜的原子层沉积（ALD）较为复杂，因为各组成氧化物的沉积行为并非相互独立。在这项研究中，通过精心设计的 ALD 工艺序列，定量研究了 SrTiO 薄膜 ALD 过程中 Ti 和 Sr 原子的掺入行为。HO 和 O 分别被用作 SrO 亚循环的氧源，而 TiO ALD 亚循环仅使用 O。除了对不同类型氧源作用的一般推测之外，其他组分氧化物亚循环所采用的氧源几乎完全控制了金属原子的掺入行为。这意味着 ALD 的前半循环在确定金属掺入速率方面起着主导作用，这揭示了在金属前体注入期间空间位阻效应对 ALD 速率的关键作用。O 与 HO 相比，对 Ti 和 Sr 前体的反应性几乎提高了一倍。尽管这些都是基于 ALD 常识的预期结果，但对每个金属原子掺入行为的定量分析为该技术重要氧化物材料的 ALD 工艺提供了有见地的观点。此外，通过 Ru-SrTiO-RuO 电容器结构获得了体介电常数高达 236 的 SrTiO 薄膜。
