Exposure apparatus

An exposure apparatus comprising:

• an optical system including an optical path of exposure light, said optical system including an optical member;
• a sealed chamber provided in said optical system and sealed off from an ambient gas around said optical system, said sealed chamber including a material generating an impurity which causes a surface of the optical member to be contaminated;
• a gas supplying system, connected to said sealed chamber, adapted to supply a predetermined gas to said sealed chamber after the predetermined gas passes through an impurity-removing filter;
• a gas exhausting system, connected to the sealed chamber, adapted to exhaust from the sealed chamber the predetermined gas supplied to the sealed chamber together with the impurity which is in said sealed chamber;
• and
• a control system, connected to said gas exhausting system and said gas supplying system, adapted to control said gas exhausting system and said gas supplying system so that exhausting of the predetermined gas including the impurity from within said sealed chamber and supplying of the predetermined gas to said sealed chamber are alternately repeated.

A projection exposure apparatus for transferring a pattern on a mask to a photosensitive substrate, comprising:

• a light source adapted to emit exposure light having a wavelength range in which a photosensitive substrate is sensitive to said exposure light;
• an illumination optical system provided between said light source and said mask;
• a projection optical system provided between said mask and said photosensitive substrate;
• a sealed chamber provided between said light source and said photosensitive substrate, said sealed chamber including a material generating an impurity which causes an intensity of said exposure light applied to said photosensitive substrate to be decreased;
• a gas exchanging system, connected to said sealed chamber, adapted to supply a predetermined gas to said sealed chamber after the predetermined gas passes through an impurity-removing filter and to exhaust the predetermined gas together with the impurity which is in said sealed chamber;
• and
• a control system, connected to said gas exchanging system, adapted to control said gas exchanging system so that a change in pressure in said sealed chamber is maintained within a predetermined range.