Suggestion of new X-ray mask using carbon substrate

The LIGA process is drawing the attention of engineers as one of the most promising technologies for fabricating nanometric/micrometric three-dimensional microstructures. It is widely recognized that in the LIGA process, the accuracy of the completed structure depends largely on the accuracy of the X-ray mask used. A resin material is conventionally used for the membrane of large X-ray masks. However, X-ray masks comprising a resin membrane have the disadvantage that, after several cycles of X-ray exposure, they crease and sag due to X-ray-derived heat. As a substitute for the conventional resin membrane, we experimentally fabricated a new X-ray mask using a carbon wafer membrane that has an extremely small thermal expansion coefficient and is easy to process. An X-ray mask having 1:1 line & space patterns at 5.3 mum intervals, with an Au absorber height of 4 mum, was fabricated on a carbon wafer substrate by applying UV lithography and electrolytic plating. The newly fabricated X-ray mask was subjected to X-ray exposure experiment using the synchrotron radiation facility New SUBARU BL-11, owned by the University of Hyogo.