Patent ID: 6535270
Filing Date: 2003-03-18
Classification: G03F

Abstract:
An exposure apparatus for transferring a pattern formed on a mask onto a photosensitized substrate by exposure, comprising:a light source to emit a light beam having a wavelength falling in a range from ultraviolet to deep ultraviolet radiation; an illumination optical system to direct said light beam from said light source into said mask; an exposure unit to make exposure of a photosensitized substrate in order to transfer said pattern formed on said mask onto said photosensitized substrate; a chamber to house at least one of said illumination optical system and said exposure unit; an ambient air introducing unit to introduce ambient air into said chamber; an impurity-removing filter to remove gaseous impurities from at least one of ambient air being introduced into said chamber and a gas recirculating in said chamber; a pair of impurity-concentration-measuring devices disposed upstream and downstream, respectively, of said impurity-removing filter; a filter end-of-life determination device to determine end-of-life of said impurity-removing filter based on measurements from said impurity-concentration-measuring device disposed upstream of said impurity-removing filter and measurements from said impurity-concentration-measuring device disposed downstream of said impurity-removing filter; and a control device to control stopping operation of said ambient air introducing unit when said impurity-concentration-measuring device disposed upstream of said impurity-removing filter has indicated a gaseous impurity concentration above a predetermined level.