Ovonic Synthetic Materials Company, Troy, Michigan 48084.
J Xray Sci Technol. 1994 Jan 1;4(2):142-50. doi: 10.3233/XST-1994-4207.
Soft x-ray projection lithography and microscopy require a high throughput and diffraction-limited performance of a multielement imaging system. To meet these requirements for a specific design it is necessary to (1) achieve high normal incidence reflectivity on each optical element while optimizing the d-spacing variation across the surface of the optical element and (2) match the rf-spacing on each optical element to that of the others according to the ray-tracing design. A technique used to achieve normal incidence reflectivity greater than 60% at 13 nm for Mo/Si and greater than 2.7% at the "water window" region for W/B4C coatings is discussed. In addition, methods to obtain a rf-spacing uniformity of ±0.4% and to match the d-spacing between imaging mirrors with an accuracy of ±0.5% are considered. A method for characterizing multilayer coatings on curved surfaces, using cylindrical witness optics with precalculated shape and radius of curvature to simulate final optics, and a manufacturing method for witness optics are also presented.
软 X 射线投影光刻和显微镜需要多元件成像系统具有高吞吐量和衍射极限性能。为了满足特定设计的这些要求，有必要 (1) 在优化光学元件表面的 d 间距变化的同时，实现每个光学元件的高正入射反射率，以及 (2) 根据光线追踪设计，使每个光学元件的射频间距与其他元件匹配。本文讨论了一种用于实现 Mo/Si 在 13nm 处的正入射反射率大于 60%，以及 W/B4C 涂层在“水窗”区域的反射率大于 2.7%的技术。此外，还考虑了获得射频间距均匀性为 ±0.4%和将成像镜之间的 d 间距匹配精度为 ±0.5%的方法。还提出了一种用于在曲面上表征多层涂层的方法，使用带有预先计算形状和曲率半径的圆柱形见证光学元件来模拟最终光学元件，以及见证光学元件的制造方法。
