In high numerical aperture (NA) extreme ultraviolet lithography, which is used to implement a finer linewidth of 10nm or lower, serious problems arise in patterning as the NA increases. To alleviate such problems, a thin absorber and a multilayer with good reflective efficiency and improved pattern quality are required. To develop an effective EUV photomask for the commercialization of high-NA systems, we determined the optimal ruthenium (Ru)/silicon (Si) multilayer structure using a phase-shift mask (PSM) absorber. A Ru/Si multilayer using PSM as an absorber has a smaller best-focus range and placement error compared to the molybdenum (Mo)/silicon (Si) multilayer. At the same time, it provides improved image contrast, enabling more stable patterning. Even when the number of layers of the Ru/Si multilayer was reduced, it was confirmed that the reflectance efficiency and image quality were maintained.

在用于实现 10nm 或更细线宽的高数值孔径 (NA) 极紫外光刻中，随着 NA 的增加，图案化会出现严重的问题。为了缓解这些问题，需要薄的吸收体和具有良好反射效率和改进图案质量的多层结构。为了开发用于高 NA 系统商业化的有效 EUV 光掩模，我们使用相移掩模 (PSM) 吸收器确定了最佳的钌 (Ru)/硅 (Si) 多层结构。Ru/Si 多层膜与钼 (Mo)/硅 (Si) 多层相比，使用 PSM 作为吸收体具有更小的最佳聚焦范围和放置误差。同时，它提供了改进的图像对比度，实现了更稳定的图案。即使Ru/Si多层的层数减少，也确认反射效率和图像质量保持不变。