Large-area, high-resolution pattern replication by the use of a two-aspherical-mirror system

A soft-x-ray projection lithography system is developed by the use of multilayer mirrors. To determine the feasibility of a high throughput and a large exposure area, we developed a reduction system that consists of two-aspherical-mirror optics. The figure errors of aspherical mirrors are evaluated by a laser interferometer. The rms aspherical figure errors of concave and convex mirrors are 8.8 and 2.0 nm, respectively, which are not enough to yield a resolution of 0.1 micrometer. The reduction optics is constructed by adjusting the mirror position to compensate for aberrations, and some trial replications are performed. An exposure area of larger than 10 mm X 0.6 mm with a fine pattern of less than a quarter micrometer is achieved.