摘要：

An embodiment of the present invention includes a technique to improve stability of a pellicle. The pellicle is pre-baked at a predetermined temperature substantially below a glass transition temperature. The pre-baked pellicle is purged with an inert gas. The purged pellicle is radiated by a radiation at a wavelength. In another embodiment, a chamber is sealed with a pellicle membrane which divides the chamber into first and second compartments. The chamber has an inflow opening in the first compartment and an outflow opening in the second compartment. A gas is injected into the inflow opening and penetrates the pellicle membrane to the outflow opening. In another embodiment, the chamber has first inflow and outflow openings and second inflow and outflow openings in the first and second compartments, respectively. A first gas is injected into the first inflow opening and a second gas into the second inflow opening. The first and second gases have a permeability difference. The first gas penetrates the pellicle membrane to the second outflow opening.

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