An air shower head of an exposure device of photolithography equipment is free of chemical substances that could otherwise contaminate a photoresist layer on a semiconductor wafer and degrade the profile of the photoresist pattern. The air shower head is interposed between a lens system of the exposure device and a wafer stage, and has a hole in the middle thereof through which exposure light can pass to a wafer supported on the stage. The air shower head includes an upper frame defining a cavity open at the bottom thereof, and a porous bottom member covering the bottom of the upper frame. The porous member is mechanically secured to bottom ends of both the inner and outer side walls of the upper frame, i.e., without the use of chemical binders, to reduce the ability of the air shower head to serve as a source of contamination.