Liu Tzu-Ling, Zeng Li, Nardi Katie L, Hausmann Dennis M, Bent Stacey F
Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305, United States.
Department of Chemical Engineering, Stanford University, 443 Via Ortega, Stanford, California 94305, United States.
Langmuir. 2021 Oct 5;37(39):11637-11645. doi: 10.1021/acs.langmuir.1c02211. Epub 2021 Sep 22.
To enable area-selective atomic layer deposition (AS-ALD), self-assembled monolayers (SAMs) have been used as the surface inhibitor to block a variety of ALD processes. The integrity of the SAM throughout the ALD process is critical to AS-ALD. Despite the demonstrated effectiveness of inhibition by SAMs, nucleation during ALD eventually occurs on SAM-protected surfaces, but its impact on SAM structures is still not fully understood. In this study, we chose the octadecyltrichlorosilane (ODTS) SAM as a model system to investigate the evolution of crystallinity and structure of SAMs before and after ALD. The breakdown behavior of SAMs when exposed to ZnO and AlO ALD was systematically studied by combining synchrotron X-ray techniques and electron microscopy. We show that the crystallinity and structure of ODTS SAMs grown on Si substrates remain intact until a significant amount of material deposition takes place. In addition, the undesired ALD materials that grow on ODTS SAMs present contrasting morphologies: dispersed nanoparticles for ZnO while relatively continuous film for AlO. Lastly, substrate dependency was explored by comparing a Si substrate to single-crystal sapphire. Similar results in the evolution of SAM crystallinity and formation of ALD nuclei on top of SAM are observed in the ODTS-sapphire system. This study provides an in-depth view of the influence of ALD processes on the SAM structure and the nucleation behavior of ALD on SAM-protected surfaces.
为实现区域选择性原子层沉积（AS-ALD），自组装单分子层（SAMs）已被用作表面抑制剂来阻断各种ALD过程。在整个ALD过程中SAM的完整性对于AS-ALD至关重要。尽管已证明SAMs具有抑制效果，但ALD过程中的成核最终仍会在SAM保护的表面上发生，但其对SAM结构的影响仍未完全了解。在本研究中，我们选择十八烷基三氯硅烷（ODTS）SAM作为模型系统，以研究ALD前后SAMs的结晶度和结构演变。通过结合同步加速器X射线技术和电子显微镜，系统地研究了SAMs在暴露于ZnO和AlO ALD时的分解行为。我们表明，在Si衬底上生长的ODTS SAMs的结晶度和结构在大量材料沉积之前保持完整。此外，在ODTS SAMs上生长的不需要的ALD材料呈现出对比鲜明的形态：ZnO为分散的纳米颗粒，而AlO为相对连续的薄膜。最后，通过将Si衬底与单晶蓝宝石进行比较来探索衬底依赖性。在ODTS-蓝宝石系统中观察到SAM结晶度演变以及在SAM顶部形成ALD核的类似结果。本研究深入了解了ALD过程对SAM结构的影响以及ALD在SAM保护表面上的成核行为。
