Extreme ultraviolet (EUV) lithography has emerged as the next generational step in advancing the manufacturing of increasingly complex semiconductor devices. The commercial viability of this new lithographic technique requires compatible photoresist (PR) materials that satisfy both the lithographic and etch requirements of good feature resolution, chemical sensitivity, a low line edge roughness, and good critical dimension uniformity. Achieving the decreased feature pitches of modern processing nodes via EUV lithography places a limit on the available photoresist thickness for a pattern transfer process. Therefore, etch processes are required to maximize the etching selectivity of a hard mask material, such as SiO₂, to an EUV photoresist. In this work, the authors evaluated the ability of an atomic layer etching (ALE) process to maximize the SiO₂/EUV PR etching selectivity. Through the flexible parameter space available in an ALE process, the authors evaluated the etching behaviors as a function of the ALE parameters of ion energy, etch step length, fluorocarbon (FC) deposition thickness, and precursor gas type. The authors found that the interaction between the energetic argon ion bombardment and a deposited FC layer produces a modified surface layer on the PR material that can strongly control the PR etch rate and even produce an etch stop under some conditions. Under the same processing conditions, the etching behavior of SiO₂ continues unimpeded, thus resulting in a high overall SiO₂/PR etching selectivity. Secondary characterization using x-ray photoelectron spectroscopy and atomic force microscopy was used to support the conclusions derived from the ellipsometric modeling based on the surface chemistry evolution and determine the impact of the ALE process on the surface roughness of the EUV PR, respectively. Additionally, attenuated total reflection Fourier-transform infrared spectroscopy was used to track the impact on specific functional groups within the PR composition from both the argon ion bombardment and FC deposition components of the ALE process. The ALE-based PR etching concept established in this work serves as a foundation for both the understanding of the impacts of an ALE process on an EUV PR material and for future works, employing an ALE process for PR-based pattern transfer.

中文翻译：

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等离子体-光致抗蚀剂相互作用对使用极紫外光致抗蚀剂的原子层蚀刻工艺的意义

极端紫外线（EUV）光刻技术已成为推进日益复杂的半导体器件制造的下一代步骤。这种新的光刻技术的商业可行性需要兼容的光刻胶（PR）材料，这些材料既要满足光刻和蚀刻的要求，又要具有良好的特征分辨率，化学敏感性，低的线边缘粗糙度和良好的临界尺寸均匀性。通过EUV光刻技术实现现代工艺节点的特征间距减小，从而限制了可用于图案转移工艺的光刻胶厚度。因此，需要蚀刻工艺以最大化诸如SiO ₂的硬掩模材料的蚀刻选择性。到EUV光刻胶。在这项工作中，作者评估了原子层蚀刻（ALE）工艺最大化SiO ₂ / EUV PR蚀刻选择性的能力。通过ALE工艺中可用的灵活参数空间，作者根据离子能量，蚀刻步长，碳氟化合物（FC）沉积厚度和前驱物气体类型等ALE参数对蚀刻行为进行了评估。作者发现，高能氩离子轰击和沉积的FC层之间的相互作用在PR材料上产生了改性的表面层，可以在某些条件下强烈控制PR蚀刻速率，甚至产生蚀刻停止。在相同的处理条件下，SiO ₂的刻蚀行为不受阻碍，因此产生了较高的整体SiO₂ / PR蚀刻选择性。使用X射线光电子能谱和原子力显微镜进行二次表征，以支持基于表面化学演化的椭圆偏振建模得出的结论，并分别确定ALE工艺对EUV PR表面粗糙度的影响。另外，使用衰减全反射傅里叶变换红外光谱来跟踪ALE工艺中氩离子轰击和FC沉积组分对PR组合物中特定官能团的影响。这项工作中建立的基于ALE的PR蚀刻概念为理解ALE工艺对EUV PR材料的影响以及为将来的工作奠定了基础，采用ALE工艺进行基于PR的图案转移。