DYNAMIC THERMAL DISTORTIONS IN AN X-RAY MASK MEMBRANE DURING PULSED X-RAY-EXPOSURE

The dynamic thermal distortion for an X-ray mask membrane has been numerically studied with special reference to the effect of elastic waves on its distortion behavior during pulsed X-ray exposure. A partial differential equation governing the dynamic behavior is derived by combining the theory of plane stress and the principle of Hamilton. The calculations based on an implicit finite difference method are performed for a SiN membrane under a 1-bar helium gas environment. Thermal displacement caused by a pulsed X-ray extends in the form of an elastic wave from a terminated rim toward a center. Critical pulse duration is offered in which the displacement in an exposure field does not occur during pulsed X-ray exposure. The peak displacement takes place with a time lag after a pulse exposure.