A technique for projection x‐ray lithography using computer‐generated holograms
Journal of Applied Physics
X-ray projection lithography has recently been explored as a method for the manufacture of < 200 nm linewidth integrated circuits. 'A method is described whereby projected lithographic images can be formed with x rays by means of a transmission hologram. Theform of the hologram is computed by an algorithm that eliminates the unwanted signals normally present as systematic errors in in-line holographic images. Example calculations are shown in which holograms are constructed to generate images
... o generate images of a given test pattern. The holographic images are shown to have excellent fidelity with respect to both resolution and contrast. Such an approach to projection x-ray lithography requires an x-ray beam with very little coherence and is thus compatible with high wafer throughput schemes; in addition, image fidelity remains high even when moderately small contaminant particles block the light from small regions of the hologram. Fabrication limits for the single optic involved-are compatible with current technological limits. The approach is applicable over a large range of soft-x-ray wavelengths, indicating the feasibility of a 100 nm resolution system with 6 pm depth of field using a carbon mask 'system operating at 5 nm, or other materials at shorter wavelengths.