The early work of John Coburn and Harold Winters revealed a synergistic effect in ion-enhanced Si etching by the concurrent irradiation of Ar⁺ and XeF₂. This finding provided an important foundation for the development of plasma dry etching processes. The experimental results of Coburn and Winters also found effects that are useful for the development of atomic layer etching (ALE) processes characterized by a self-limited etch rate. ALE approaches are widely established and can be utilized in either directional or isotropic etching by employing proper surface modification and product removal steps. Nevertheless, the development of material selective ALE processes is still limited. An approach that combines substrate-selective deposition with etching opens a new processing window for selective ALE. The authors studied the deposition behavior of mixtures of methane (CH₄) with trifluoromethane (CHF₃) and mixtures of methane with octafluorocyclobutane (C₄F₈) on HfO₂ and Si surfaces. The experimental results show that a CH₄/C₄F₈ mixture produces a comparable fluorocarbon (FC) deposition thickness on both HfO₂ and Si during the deposition step. In contrast, a CH₄/CHF₃ mixture deposits an FC film on Si, whereas it fluorinates the HfO₂ surface with negligible FC deposition. Utilizing these behaviors allows for an ALE process based on CH₄/CHF₃ for selective removal of HfO₂ over Si. Surface characterization data that provide mechanistic insights into these processes are also provided and discussed.

中文翻译：

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通过前体和与衬底有关的选择性沉积，在硅上选择性地蚀刻HfO2

John Coburn和Harold Winters的早期工作揭示了通过同时辐照Ar ⁺和XeF ₂在离子增强的Si蚀刻中具有协同效应。。这一发现为等离子体干法刻蚀工艺的发展提供了重要的基础。Coburn和Winters的实验结果还发现了对以自限腐蚀速率为特征的原子层腐蚀（ALE）工艺发展有用的效果。ALE方法已被广泛建立，并且可以通过采用适当的表面改性和产品去除步骤在定向或各向同性蚀刻中使用。然而，材料选择性ALE工艺的开发仍然受到限制。将衬底选择性沉积与蚀刻相结合的方法为选择性ALE打开了新的处理窗口。作者研究了甲烷（CH ₄）与三氟甲烷（CHF ₃）混合物的沉积行为）和HfO ₂和Si表面上的甲烷与八氟环丁烷（C ₄ F ₈）的混合物。实验结果表明，在沉积步骤中，CH ₄ / C ₄ F ₈混合物在HfO ₂和Si上均产生可比的碳氟化合物（FC）沉积厚度。相反，CH ₄ / CHF ₃混合物在Si上沉积FC膜，而在HfO ₂表面氟化，而FC沉积可忽略不计。利用这些行为，可以实现基于CH ₄ / CHF ₃的ALE工艺选择性去除HfO ₂在硅上。还提供并讨论了可提供对这些过程的机械洞察力的表面表征数据。