A refined model of an extreme ultraviolet (EUV) mask stack consisting of the Mo/Si multilayer coated by a Ru protective layer and a TaBN/TaBO absorber layer was developed to facilitate accurate simulations of EUV mask performance for high-NA EUV photo-lithography (EUVL) imaging. The model is derived by combined analysis of the measured EUV and x ray reflectivity of an industry-representative mask blank. These two sets of measurements were analyzed using a combined free-form analysis procedure that delivers high-resolution x ray and EUV optical constant depth profiles based on self-adapted sets of sublayers as thin as 0.25 nm providing a more accurate description of the reflectivity than obtained from only EUV reflectivity. “Free-form analysis” means that the shape of the layer interfaces in the model is determined experimentally and is not given a priori by the structure model. To reduce the numerical effort for EUV imaging simulations, a low-resolution model of the multilayer and absorber stack with sublayer thicknesses larger than 2 nm, that fits to only the EUV reflectance, was derived from the high-resolution model. Rigorous high-NA EUVL simulations were done to compare the performance of the new model to our previous work [Proc. SPIE 8886, 88860B (2013) [CrossRef] ].

中文翻译：

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精制的极紫外面罩堆叠模型

开发了由紫外线保护层和TaBN / TaBO吸收层覆盖的Mo / Si多层膜组成的极紫外（EUV）掩模叠层的精细模型，以促进对高NA EUV光刻的EUV掩模性能的精确模拟。 （EUVL）成像。该模型是通过对行业代表性口罩毛坯的实测EUV和X射线反射率进行组合分析得出的。使用组合的自由形式分析程序对这两组测量进行了分析，该程序可根据自适应的子层组（薄至0.25 nm）提供高分辨率的X射线和EUV光学恒定深度剖面，从而提供比反射率更准确的描述。仅从EUV反射率获得。“自由形式分析”是指模型中层界面的形状是通过实验确定的，没有给出结构模型的先验性。为了减少EUV成像仿真的数值工作，从高分辨率模型中得出了一个子层厚度大于2 nm的多层和吸收体堆叠的低分辨率模型，该模型仅适合EUV反射率。进行了严格的高NA EUVL仿真，以将新模型的性能与我们以前的工作进行比较[Proc。SPIE 8886，88860B（2013）[交叉引用] ]。