X-ray mask distortion due to radiation damage

During use X-ray masks will receive very large accumulated doses, perhaps as high as 0.5 MJ/cm2. Because the allowed mask distortion for 0.25 μm ground rules is of the order of 0.075 μm, the permissible radiation-induced distortion is {reversed tilde equals} 0.025 μm, thus requiring substrate materials with negligible distortion when subjected to large radiation doses. The in-plane distortion of various X-ray mask substrate candidates when subjected to large accumulated doses, up to 51,000 J/cm2, is reported. © 1991.