The transmissivity of thin photoresist films and its variation during exposure are key parameters in photolithographic processing, but their measurement is far from straightforward at extreme ultraviolet (EUV) wavelength. In this work, we analyze thin films of chemically amplified resists, specifically designed for EUV lithography, synthesized with two different backbone polymers and two different photoacid generators with concentrations ranging from 0 to 140% baseline. The static absorption coefficient α and the variation of transmissivity upon exposure to EUV light (i.e. the Dill parameter C) are measured experimentally with our established methodology. The Dill parameter C, or bleaching, is interpreted in terms of outgassing and it is correlated with the rate of photoacid decomposition to extract the exposure kinetics and the quantum yield. In addition, the dose to clear of each formulation is measured to determine the lithographic sensitivity. It was found that not only the photoacid molecule but also its interaction with the polymer backbone affects bleaching and thus the quantum yield. These experimental observables (α, the Dill parameter C and dose to clear) allow us to determine the amount of clearing volume of the photoresist per unit photoacid. The clearing volume is then discussed as a microscopic figure of merit for the deprotection radius in chemically amplified resists and in light of the pursuit of ultimate resolution in EUV lithography.

中文翻译：

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光酸产生剂-聚合物相互作用对化学放大抗蚀剂的量子产率产生影响，用于极端紫外光刻†

光刻胶薄膜的透射率及其在曝光过程中的变化是光刻处理中的关键参数，但在极端紫外（EUV）波长下，它们的测量远非直截了当。在这项工作中，我们分析了专门为EUV光刻设计的化学放大抗蚀剂薄膜，该薄膜是由两种不同的主链聚合物和两种不同的光酸产生剂合成而成的，浓度范围为0％至140％。静态吸收系数α和暴露于EUV光线时的透射率变化（即Dill参数C）是通过我们既定的方法进行实验测量的。莳萝参数C脱色是用脱气来解释的，它与光酸分解的速率相关，以提取曝光动力学和量子产率。另外，测量清除每种制剂的剂量以确定平版印刷敏感性。已经发现，不仅光酸分子而且其与聚合物主链的相互作用都影响漂白，从而影响量子产率。这些实验观察值（α，Dill参数C和要清除的剂量）使我们能够确定每单位光酸的光致抗蚀剂的清除量。然后，根据在EUV光刻中追求最终分辨率的要求，讨论清除量，作为化学放大抗蚀剂中脱保护半径的微观品质因数。