X-ray mask repair

A method for repairing X-ray lithographic masks using focused ion beam technology is described and demonstrated. The ion beam is used for mask imaging, for absorber milling for opaque repair, and for deposition of X-ray-opaque material for clear repair. Solutions to the unique problems faced in executing these tasks on the high-resolution, high-aspect-ratio patterns characteristic of X-ray masks are discussed. Several effects of material redeposition during opaque repair are explored. The significance of this same redeposition during clear repair and the resulting advantage gained in using a high-yield deposition process are illustrated. Examples of repairs and printed images of these repairs are shown for feature sizes smaller than 0.25 µm.