Experimental evaluation of an optimized radiation cooling geometry for ion projection lithography masks

In this article, we study an optimized radiative cooling geometry for ion projection lithography masks. In this design, a polished infrared mirror guides radiation from the mask to a high-emissivity cooled-cylinder positioned about 0.5 m away. Previous finite element modeling of this system predicts thermal distortion below 1 nm for practical mask designs. This is the first experimental study of the design. We show, by measuring the mean mask stress as a function of cooled cylinder temperature, that radiative cooling balances beam heating, with a power density of 2.15 mW/cm 2 , when the cooled cylinder is held at 15 ° C and the temperature of the mirror and mask frame are at 25 ° C . The results agree with finite element modeling.