METHOD OF CONTROLLING AIR PRESSURE IN CHAMBER, APPARATUS FOR THE SAME, AND EXPOSURE APPARATUS

摘要

A method of controlling air pressure in a chamber, wherein the air pressure in a chamber in which laser measurement is conducted is maintained at a set level with respect to the variation of an external air pressure, characterized by comprising detecting the external air pressure, determining a long-standing flat pressure value with respect to short-term fluctuation of the detected external air pressure, preparing a set inside-chamber air pressure by adding a predetermined air pressure to the flat pressure value thus determined, and detecting an inside-chamber air pressure while introducing an outside air so that the inside-chamber air pressure reaches the set air pressure.