ASML Holding N.V.
Apparatus for delivering gas and illumination source for generating high harmonic radiation

Abstract:

Disclosed is a high harmonic generation (HHG) radiation source which may be used to generate measurement radiation for an inspection apparatus. In such a radiation source, a pump radiation source is operable to emit pump radiation at a high harmonic generation gas medium thereby exciting the high harmonic generation gas medium within a pump radiation interaction region so as to generate the high harmonic radiation and an ionization radiation source is operable to emit ionization radiation at the high harmonic generation gas medium to ionize a gas at an ionization region between the pump radiation interaction region and an optical output of the illumination source.