Tezsevin I, Deijkers J H, Merkx M J M, Kessels W M M, Sandoval T E, Mackus A J M
Department of Applied Physics and Science Education, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Department of Chemical and Environmental Engineering, Universidad Técnica Federico Santa María, 2340000 Santiago, Chile.
J Phys Chem Lett. 2024 Jul 25;15(29):7496-7501. doi: 10.1021/acs.jpclett.4c01632. Epub 2024 Jul 16.
Atomic layer deposition (ALD) processes are known to deposit submonolayers of material per cycle, primarily attributed to steric hindrance and a limited number of surface sites. However, an often-overlooked factor is the random sequential adsorption (RSA) mechanism, where precursor molecules arrive one-by-one and adsorb at random surface sites. Consequently, the saturation coverage of precursors significantly deviates from ideal closed packing. In this study, we investigated the influence of RSA on precursor adsorption saturation and, consequently, on the growth per cycle (GPC) of the ALD processes. Our simulations revealed that the RSA model leads to a 22% to 40% lower surface density compared to the reference case of ordered packing. Furthermore, based on the precursor shape and size, we estimated GPC values with an average accuracy of 0.05 Å relative to experimental literature data. This work shows the critical role of RSA in ALD, emphasizing the need to consider this mechanism for a more accurate process design and optimization.
已知原子层沉积（ALD）工艺每循环沉积的材料为亚单层，这主要归因于空间位阻和有限数量的表面位点。然而，一个常被忽视的因素是随机顺序吸附（RSA）机制，在前体分子逐一到达并随机吸附在表面位点的情况下，前驱体的饱和覆盖率显著偏离理想的紧密堆积。在本研究中，我们研究了RSA对前驱体吸附饱和度的影响，进而对ALD工艺的每循环生长量（GPC）的影响。我们的模拟结果表明，与有序堆积的参考情况相比，RSA模型导致表面密度降低22%至40%。此外，基于前驱体的形状和尺寸，我们相对于实验文献数据估计了GPC值，平均准确度为0.05 Å。这项工作表明了RSA在ALD中的关键作用，强调了为更精确的工艺设计和优化而考虑这一机制的必要性。
