Three x-ray mask-making methods a

摘要

Abstract: The fabrication of x-ray mask is an important step in the LIGA process. Thick absorber patterns for working masks to produce microstructures with high aspect ratio are desired to skip the intermediate mask fabrication. This article illustrates three x-ray mask-making methods applied for LIGA process, special for working masks. Three mask-making methods include mechanically machined mask, micro-EDM machining mask, and E- beam written mask. The mechanically machined mask method is the simplest and fastest among three methods, but it has geometry limitations and material hardness restrictions. Gold absorber and graphite membrane are composed to be a working mask, absorber patterns with dimensional bias are up to 5 micrometer in a 150 micrometer feature size. Micro-EDM machining mask method has the possibility to achieve the accuracy requirement in submicron range if its stage control is improved. The experiments showed that 2 micrometer error existed from the designed size. The E-beam written mask is the best method now available to accomplish the dimensional requirements in submicron range, its dimensional accuracy is within 0.5 micrometer after exposure. All three masks are successful to produce at least 500 micrometer thick PMMA microstructures after exposure, it also means that at least 500 micrometer thick metallic microstructures has been made by using an electroforming process. !10