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|1. (WO2018104109) METHOD FOR REPAIRING REFLECTIVE OPTICAL ELEMENTS FOR EUV LITHOGRAPHY|
|Applicants:||CARL ZEISS SMT GMBH
|Title:||METHOD FOR REPAIRING REFLECTIVE OPTICAL ELEMENTS FOR EUV LITHOGRAPHY|
The invention relates to a cost-effective method for repairing reflective optical elements for EUV lithography. Said elements have a substrate (61), and a coating (62) that reflects at a working wavelength in the range between 5 nm and 20 nm and is damaged as a result of the formation of hydrogen bubbles. The method comprises the following steps: localizing a damaged area (63, 64, 65, 66) in the coating (62) and covering the damaged area (63, 64, 65, 66) with one or more materials having low hydrogen permeability by applying a cover element to the damaged area, wherein the cover element is formed of a surface structure, a convex or concave surface, or a coating corresponding to the coating of the reflective optical element, or a combination thereof. The method is particularly suitable for collector mirrors (70) for EUV lithography. After the repair, they have cover elements (71, 72, 73).