Patent ID: 8884257

Claim:
A chamber apparatus used with an external apparatus having an obscuration region, the chamber apparatus comprising: a chamber in which EUV light is generated; a collector mirror configured to collect the EUV light generated inside the chamber; a first through-hole formed in a region aside from the center of the collector mirror, the first through-hole being located in a region substantially corresponding to the obscuration region; a second through-hole formed in the collector mirror, through which an externally-applied laser beam travels; an etching gas supply unit provided in the first through-hole and configured to supply an etching gas into the chamber, the etching gas supply unit including an outlet through which the etching gas is discharged; and a magnetic field generator configured to generate a magnetic field inside the chamber, wherein the outlet is oriented only toward a part of a periphery of the collector mirror located in a region near the magnetic field generator corresponding to the obscuration region.