Patent ID: 8546775

Claim:
A method for stabilizing a source location during discharge plasma-based generation of extreme ultraviolet radiation comprising the steps of: providing a vaporization beam of pulsed high-energy radiation by means of a pulsed high-energy radiation source; directing the vaporization beam via a first beam aligning unit, a beam focusing unit and a second beam aligning unit, to a predetermined vaporization location for vaporizing emitter material between two electrodes arranged in a vacuum chamber; acquiring first actual direction values in two coordinates from the vaporization beam by means of a first measuring device coupled with the vaporization beam via a first beamsplitter prior to the vaporization beam's impingement on the first beam aligning unit; determining and storing first direction deviations of the vaporization beam in a storage unit by comparing the first actual direction values with first reference direction values; correcting a second beam aligning unit in two coordinates to compensate for the first direction deviations of the vaporization beam; acquiring second actual direction values in two coordinates from the vaporization beam by means of a second measuring device coupled with/to the vaporization beam via a second beamsplitter downstream of the first beam aligning unit; determining and storing second direction deviations of the vaporization beam in the storage unit with respect to the predetermined vaporization location's direction by comparing the second actual direction values with second reference direction values; correcting the first beam aligning unit in two coordinates to compensate for the second direction deviations of the vaporization beam; acquiring actual divergence values from the vaporization beam by means of a third measuring device coupled with/to the vaporization beam via a third beamsplitter downstream of the first beam aligning unit; determining and storing divergence deviations of the vaporization beam in the storage unit, via a third measuring device, by comparing the actual divergence values with reference divergence values for which the vaporization beam is focused into the predetermined vaporization location along a corrected direction of the vaporization beam; and correcting the beam focusing unit to compensate for the divergence deviations of the vaporization beam to adjust the focusing of the vaporization beam at the predetermined vaporization location.