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-mu-m ground rules is of the order of 0.075-mu-m, the permissible radiation-induced distortion is congruent-to 0.025-mu-m, 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.