In thermal atomic layer etching (ALE) of Ni, a thin oxidized Ni layer is removed by a hexafluoroacetylacetone (hfacH) etchant gas at an elevated surface temperature, and etching ceases when a metallic Ni surface appears (self-limiting step). However, atomistic details of the self-limiting step was not well understood. With periodic density-functional-theory calculations, it is found that hfacH molecules barrierlessly adsorb and tend to decompose on a metallic Ni surface, in contrast to the case of a NiO surface, where they can form volatile Ni(hfac) 2 . Our results clarify the origin of the self-limiting process in the thermal ALE.

中文翻译：

---

六氟乙酰丙酮对镍进行热原子层蚀刻的自限制过程

在Ni的热原子层蚀刻（ALE）中，通过六氟乙酰丙酮（hfacH）蚀刻剂气体在较高的表面温度下去除了一层氧化的Ni薄层，当出现金属Ni表面时，蚀刻停止（自限制步骤）。但是，人们对自我限制步骤的原子细节还不太了解。通过周期性的密度泛函理论计算，发现hfacH分子在金属Ni表面无障碍地吸附并易于分解，这与NiO表面可以形成挥发性Ni（hfac）2的情况相反。我们的结果阐明了热ALE中自限过程的起源。