The present disclosure relates to an optical apparatus and its vibration removing method.
For a lithography technology that plays an important role in the miniaturization of semiconductor devices, ArF lithography in which an ArF excimer laser having an exposure wavelength of 193 nm is used as an exposure light source is currently used for mass-production. Further, an immersion technique (also called “ArF immersion lithography”) for increasing the resolution of an exposure device by filling a space between its objective lens and a wafer with water has also begun to be used for mass production. In order to advance the miniaturization of semiconductor devices even further, development of various techniques for putting EUVL (Extremely Ultraviolet Lithography) having an exposure wavelength of 13.5 nm to practical use has been in progress.
In an apparatus using EUV light, an optical system is disposed inside a vacuum chamber so that an optical path is in a vacuum. When there is a vacuum pump and/or a driving mechanism such as a stage, vibrations occur. Further, in some cases, vibrations occur in a light source. Therefore, an exposure apparatus using a vibration removal table is disclosed.
An EUV exposure apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2005-136120 includes two vibration removal tables. While one of the vibration removal tables removes vibrations from a stage apparatus and a loader, the other vibration removal table removes vibrations from an illumination optical system and a projection optical system. A vibration removal apparatus disclosed in Japanese Unexamined Patent Application Publication No. H11-264444 includes a vibration removal table using an air spring.
An exposure apparatus disclosed in Japanese Unexamined Patent Application Publication No. H11-327155 includes an exposure apparatus main unit, a laser oscillation unit, and a vibration removal table. All the units disposed in the exposure apparatus main unit are mounted on the vibration removal table. Further, the laser oscillation unit is connected to the exposure apparatus main unit through an accordion connection part. In this way, vibrations in the laser oscillation unit are prevented from propagating to the exposure apparatus main unit.