Hennessy John, Jewell April D, Jones John-Paul, Crouch Garrison M, Nikzad Shouleh
Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, United States.
Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States.
ACS Appl Mater Interfaces. 2021 Jan 27;13(3):4723-4730. doi: 10.1021/acsami.0c19399. Epub 2021 Jan 11.
Surface fluorination and volatilization using hydrogen fluoride and trimethyaluminum (TMA) is a useful approach to the thermal atomic layer etching of AlO. We have previously shown that significant enhancement of the TMA etching effect occurs when performed in the presence of lithium fluoride chamber-conditioning films. Now, we extend this enhanced approach to other alkali halide compounds including NaCl, KBr, and CsI. These materials are shown to have varying capacities for the efficient removal of AlF and ultimately lead to larger effective AlO etch rates at a given substrate temperature. The most effective compounds allow for continuous etching of AlO at substrate temperatures lower than 150 °C, which can be a valuable route for processing temperature-sensitive substrates and for improving the selectivity of the etch over other materials. The strong interaction between TMA and alkali halide materials also results in material-selective thin-film deposition at these reduced substrate temperatures. We discuss possible mechanisms of this etching enhancement and prospects for extending this approach to other material systems. The consequences of using TMA as an ALD and ALE precursor are discussed in the context of interface engineering for alkali-containing substrates such as lithium battery materials.
使用氟化氢和三甲基铝（TMA）进行表面氟化和挥发是对AlO进行热原子层蚀刻的一种有用方法。我们之前已经表明，当在存在氟化锂腔室调节膜的情况下进行时，TMA蚀刻效果会显著增强。现在，我们将这种增强方法扩展到其他碱金属卤化物化合物，包括NaCl、KBr和CsI。结果表明，这些材料在有效去除AlF方面具有不同的能力，并最终在给定的衬底温度下导致更高的有效AlO蚀刻速率。最有效的化合物能够在低于150°C的衬底温度下连续蚀刻AlO，这对于处理对温度敏感的衬底以及提高蚀刻相对于其他材料的选择性而言可能是一条有价值的途径。TMA与碱金属卤化物材料之间的强相互作用还会在这些降低的衬底温度下导致材料选择性薄膜沉积。我们讨论了这种蚀刻增强的可能机制以及将该方法扩展到其他材料系统的前景。在含碱衬底（如锂电池材料）的界面工程背景下，讨论了使用TMA作为ALD和ALE前驱体的后果。
