Merkx Marc J M, Angelidis Athanasios, Mameli Alfredo, Li Jun, Lemaire Paul C, Sharma Kashish, Hausmann Dennis M, Kessels Wilhelmus M M, Sandoval Tania E, Mackus Adriaan J M
Department of Applied Physics, Eindhoven University of Technology, 5600MB Eindhoven, The Netherlands.
TNO-Holst Centre, 5656 AE Eindhoven, The Netherlands.
J Phys Chem C Nanomater Interfaces. 2022 Mar 17;126(10):4845-4853. doi: 10.1021/acs.jpcc.1c10816. Epub 2022 Mar 8.
Implementation of vapor/phase dosing of small molecule inhibitors (SMIs) in advanced atomic layer deposition (ALD) cycles is currently being considered for bottom-up fabrication by area-selective ALD. When SMIs are used, it can be challenging to completely block precursor adsorption due to the inhibitor size and the relatively short vapor/phase exposures. Two strategies for precursor blocking are explored: (i) physically covering precursor adsorption sites, i.e., steric shielding, and (ii) eliminating precursor adsorption sites from the surface, i.e., chemical passivation. In this work, it is determined whether steric shielding is enough for effective precursor blocking during area-selective ALD or whether chemical passivation is required as well. At the same time, we address why some ALD precursors are more difficult to block than others. To this end, the blocking of the Al precursor molecules trimethylaluminum (TMA), dimethylaluminum isopropoxide (DMAI), and tris(dimethylamino)aluminum (TDMAA) was studied by using acetylacetone (Hacac) as inhibitor. It was found that DMAI and TDMAA are more easily blocked than TMA because they adsorb on the same surface sites as Hacac, while TMA is also reactive with other surface sites. This work shows that chemical passivation plays a crucial role for precursor blocking in concert with steric shielding. Moreover, the reactivity of the precursor with the surface groups on the non-growth area dictates the effectiveness of blocking precursor adsorption.
目前正在考虑在先进的原子层沉积（ALD）循环中采用小分子抑制剂（SMIs）的气相/相剂量法，以通过区域选择性ALD进行自下而上的制造。当使用SMIs时，由于抑制剂的尺寸和相对较短的气相/相暴露时间，要完全阻止前驱体吸附可能具有挑战性。本文探索了两种阻止前驱体的策略：（i）物理覆盖前驱体吸附位点，即空间位阻屏蔽，以及（ii）从表面消除前驱体吸附位点，即化学钝化。在这项工作中，我们确定空间位阻屏蔽对于区域选择性ALD期间有效阻止前驱体是否足够，或者是否也需要化学钝化。同时，我们探讨了为什么一些ALD前驱体比其他前驱体更难被阻止。为此，我们使用乙酰丙酮（Hacac）作为抑制剂，研究了铝前驱体分子三甲基铝（TMA）、二甲基铝异丙醇盐（DMAI）和三（二甲基氨基）铝（TDMAA）的阻止情况。结果发现，DMAI和TDMAA比TMA更容易被阻止，因为它们与Hacac吸附在相同的表面位点上，而TMA还与其他表面位点发生反应。这项工作表明，化学钝化与空间位阻屏蔽协同作用，在阻止前驱体方面起着关键作用。此外，前驱体与非生长区域表面基团的反应性决定了阻止前驱体吸附的有效性。
