Study of irradiation damage of Sc/Si multilayer mirrors with a 46.9-nm tabletop laser
Abstract
We demonstrate the use of a tabletop capillary-discharge Ne-like Ar laser emitting nanosecond duration pulses at a wavelength of 46.9 nm for investigation of radiation damage mechanism and damage threshold in Sc/Si extreme ultraviolet multilayer mirrors. To vary the emission load at the surface of the mirror under test the intense 0.13 mJ laser pulses were focused using a spherical Sc/Si multilayer mirror to obtain fluences ranging from ~ 0.01 to >10 J/cm2. Single spots and large area patterns (2x2 mm2) were irradiated depending on the type of surface analysis technique employed. Damage threshold fluences of ~ 0.08 J/cm2 were measured for Sc/Si coatings deposited on both borosilicate glass and Si substrates, compared to the 0.7 J/cm2 found necessary to damage a bare Si substrate. The use of scanning and transmission electron microscopy, and small-angle X-ray diffraction techniques revealed the thermal nature of the damage mechanism. These results are relevant to the use of the Sc/Si mirrors in combination with newly developed high power EUV sources, and provide a benchmark for their further improvement.
- Publication:
-
Fourth Generation X-Ray Sources and Optics II
- Pub Date:
- November 2004
- DOI:
- 10.1117/12.557952
- Bibcode:
- 2004SPIE.5534...53V