OPTIMAL-DESIGN OF AN X-RAY-LITHOGRAPHY MASK

The 0.25-mu-m 1:1, masks used in x-ray lithography have a very tight overlay requirement: it is not just sufficient to produce a perfect mask, it is also necessary not to degrade its characteristics by incorrect mounting. This is particularly true for synchrotron-based x-ray lithography where the masks are patterned and used in different configurations. The computational tools necessary to model mask distortions in the nanometer range with high accuracy and reliability are developed here and used to predict an optimal mask design. The results show that the overall mask distortion resulting from gravitational loading can be accommodated within the allocated error budget.