Methods for forming X-ray images having 0.25 .mu.m minimum line widths on X-ray sensitive material are presented. A holgraphic image of a desired circuit pattern is projected onto a wafer or other image-receiving substrate to allow recording of the desired image in photoresist material. In one embodiment, the method uses on-axis transmission and provides a high flux X-ray source having modest monochromaticity and coherence requirements. A layer of light-sensitive photoresist material on a wafer with a selected surface is provided to receive the image(s). The hologram has variable optical thickness and variable associated optical phase angle and amplitude attenuation for transmission of the X-rays. A second embodiment uses off-axis holography. The wafer receives the holographic image by grazing incidence reflection from a hologram printed on a flat metal or other highly reflecting surface or substrate. In this second embodiment, an X-ray beam with a high degree of monochromaticity and spatial coherence is required.
FIELD OF THE INVENTION
This invention relates to X-ray lithography for feature sizes below 0.25 .mu.m. This invention was made, in part, with Govermnent Support under Contract DE-AC03-76SF00098 between the U.S. Department of Energy and the University of California for the operation of the Lawrence Berkeley Laboratory and in part with support from the State University of New York. The United States Government and the Research Foundation of the State University of New York have certain rights in this invention.