Alam Mohammed Sadman, Motin Md Abdul, Zaera Francisco
Department of Chemistry, University of California, Riverside, California 92521, United States.
J Phys Chem C Nanomater Interfaces. 2025 May 7;129(20):9394-9404. doi: 10.1021/acs.jpcc.5c02266. eCollection 2025 May 22.
The effectiveness of silylation treatments of silicon oxide surfaces using -(trimethylsilyl)-dimethylamine (TMSDMA) for the passivation of atomic layer depositions (ALDs) was evaluated by using X-ray photoelectron spectroscopy (XPS). It was determined that such silylation does indeed block the silanol (Si-OH) nucleation centers where the ALD precursors react and therefore inhibits film growth, but only temporarily; after a few ALD cycles, deposition becomes evident. By testing this chemistry on two types of SiO surfaces, prepared by plasma-enhanced chemical vapor deposition (PE-CVD) and by chemical (RCA) treatment of Si(100) wafers, it was concluded that the nature of the initial substrate does not play a crucial role in the silylation or ALD blocking processes. The material being deposited, on the other hand, does make a difference: TiO film growth can be blocked for almost 10 ALD cycles, whereas HfO starts building up on the surface after less than 5 ALD cycles. Moreover, the steady-state deposition rate reached for TiO on the silylated surfaces is lower than that seen for the untreated substrate, whereas with HfO not only is that not the case, but the new films may in fact grow as 3D nanostructures. One of the key findings of this work is that the silylation can be carried out using either gas- or liquid-phase treatments. It was found that the extent of silylation and the inhibition of the subsequent ALD were comparable in both cases, but the gas-phase method was determined to be cleaner and to deposit less carbon contaminants. This silylation-based ALD inhibition is expected to be selective with respect to the nature of the substrate and therefore useful for the design of area-selective ALD (AS-ALD) processes.
使用X射线光电子能谱（XPS）评估了用-（三甲基甲硅烷基）二甲胺（TMSDMA）对氧化硅表面进行硅烷化处理以钝化原子层沉积（ALD）的有效性。结果表明，这种硅烷化确实会阻断ALD前驱体发生反应的硅醇（Si-OH）成核中心，从而抑制薄膜生长，但只是暂时的；经过几个ALD循环后，沉积就会变得明显。通过在两种类型的SiO表面上测试这种化学方法，这两种表面分别是通过等离子体增强化学气相沉积（PE-CVD）和对Si(100)晶片进行化学（RCA）处理制备的，得出的结论是初始衬底的性质在硅烷化或ALD阻断过程中并不起关键作用。另一方面，正在沉积的材料确实会产生影响：TiO薄膜生长可以被阻断近10个ALD循环，而HfO在不到5个ALD循环后就开始在表面堆积。此外，在硅烷化表面上TiO达到的稳态沉积速率低于未处理衬底的沉积速率，而对于HfO，情况并非如此，而且新薄膜实际上可能以三维纳米结构生长。这项工作的一个关键发现是，可以使用气相或液相处理进行硅烷化。结果发现，在这两种情况下，硅烷化程度和对后续ALD的抑制作用相当，但气相方法被确定更清洁，并且沉积的碳污染物更少。这种基于硅烷化的ALD抑制预计对衬底的性质具有选择性，因此可用于区域选择性ALD（AS-ALD）工艺的设计。
